US20010034070A1 - Apparatus and method for testing fuses - Google Patents

Apparatus and method for testing fuses Download PDF

Info

Publication number
US20010034070A1
US20010034070A1 US09/854,541 US85454101A US2001034070A1 US 20010034070 A1 US20010034070 A1 US 20010034070A1 US 85454101 A US85454101 A US 85454101A US 2001034070 A1 US2001034070 A1 US 2001034070A1
Authority
US
United States
Prior art keywords
testing
circuit
voltage
supply node
time
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
US09/854,541
Other versions
US6410352B2 (en
Inventor
Tim Damon
Phillip Byrd
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Micron Technology Inc
Original Assignee
Micron Technology Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Micron Technology Inc filed Critical Micron Technology Inc
Priority to US09/854,541 priority Critical patent/US6410352B2/en
Publication of US20010034070A1 publication Critical patent/US20010034070A1/en
Application granted granted Critical
Publication of US6410352B2 publication Critical patent/US6410352B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/30Structural arrangements specially adapted for testing or measuring during manufacture or treatment, or specially adapted for reliability measurements
    • H01L22/34Circuits for electrically characterising or monitoring manufacturing processes, e. g. whole test die, wafers filled with test structures, on-board-devices incorporated on each die, process control monitors or pad structures thereof, devices in scribe line
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28Testing of electronic circuits, e.g. by signal tracer
    • G01R31/316Testing of analog circuits
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/74Testing of fuses
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/52Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
    • H01L23/522Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
    • H01L23/525Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body with adaptable interconnections
    • H01L23/5252Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body with adaptable interconnections comprising anti-fuses, i.e. connections having their state changed from non-conductive to conductive
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00Details of semiconductor or other solid state devices
    • H01L23/52Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
    • H01L23/522Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
    • H01L23/525Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body with adaptable interconnections
    • H01L23/5256Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body with adaptable interconnections comprising fuses, i.e. connections having their state changed from conductive to non-conductive
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001Technical content checked by a classifier
    • H01L2924/0002Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Definitions

  • the present invention relates to semiconductor based memory devices, and in particular to testing fuses in integrated memory circuits.
  • both bank switch SB 1 and fuse switch SF 2 must be actuated.
  • the measurement time obtained is referred to as a t test value.
  • the individual t test value for a particular fuse is plotted against the resistance value for such particular fuse, and this step is performed for all measured fuses.
  • a decision is made as to what resistance value is indicative of a fuse that has been programmed properly. For example, it may be decided that a resistance value of 300 K ⁇ or less indicated that the fuse being tested has been properly programmed.
  • t test value the comparator output switched for a majority of the fuses measured having resistance values of 300 K ⁇ or less.
  • the comparator 30 has a reference 55 which, in the prior art, is hardwired to a particular voltage value.
  • the switch time period t fuse is highly dependent on the voltage value to which the reference in the comparator 30 is connected. For example, suppose the reference in the comparator 30 is hardwired to 2.5 V, so that when the voltage level on SGND node 10 drops below 2.5 V the output of the comparator 30 switches high. It is possible for the output of the comparator 30 to switch even at a reference voltage greater than 2.5 V (e.g. 3.0 V), thus decreasing the testing time required.
  • a reference voltage greater than 2.5 V e.g. 3.0 V
  • the present invention is directed to a method and circuit for testing fuses in memory integrated circuits such as those discussed above.
  • One embodiment of the invention is a circuit comprising a test bank of control resistors and a testing circuit, wherein the bank of control resistors establishes a test period of all fuses being tested.
  • the testing circuit comprises a comparator having a reference voltage for comparison to a node voltage, wherein an external access to the reference of the comparator is provided. This external access to the reference of the comparator permits the minimization of test times.
  • the step of determining the testing time for a fuse comprises the steps of allowing to decay the voltage applied to the node, and waiting a time period for the voltage applied to the node to decay to a voltage less than or equal to the reference voltage applied to the comparator.
  • the method includes, after the step of comparing the testing time for the fuse against the testing time for the control resistor, the step of deciding whether the testing time for the fuse meets predetermined specification parameters based on the testing time for the control resistor.
  • FIG. 1 is a circuit diagram depicting a prior art technique for testing fuses in integrated memory circuits
  • FIG. 2 is a circuit diagram showing an embodiment of the present invention
  • FIG. 3 is a circuit diagram showing another embodiment of the present invention.
  • FIG. 4 is a circuit diagram showing yet another embodiment of the present invention.
  • FIG. 5 is a circuit diagram showing an embodiment of a variable reference voltage
  • FIG. 6 is a representative circuit diagram showing an alternative resistance configuration
  • FIG. 7 is a flowchart block diagram depicting a method of the present invention.
  • FIG. 8 is a block diagram of a memory to which embodiments of the present invention may be electrically connected.
  • FIG. 9 is a perspective view of a typical computer system to which embodiments of the present invention may be electrically connected.
  • wafer and substrate used in the following description include any semiconductor-based structure having an exposed surface with which to form the integrated circuit structure of the invention. Wafer and substrate are used interchangeably to refer to semiconductor structures during processing, and may include other layers that have been fabricated thereupon.
  • Both wafer and substrate include doped and undoped semiconductors, epitaxial semiconductor layers supported by a base semiconductor or insulator, as well as other semiconductor structures well known to one skilled in the art.
  • doped and undoped semiconductors epitaxial semiconductor layers supported by a base semiconductor or insulator, as well as other semiconductor structures well known to one skilled in the art.
  • the following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.
  • FIG. 2 depicts an embodiment 200 of the present invention.
  • a bank 202 comprising a plurality of control resistors comprising a plurality of resistors R 1 , R 2 , R 3 , . . . R N , and a plurality of switches SR 1 , SR 2 , SR 3 , . . . SR N , is electrically interposed between SGND or first supply node 204 and a second supply node 206 , which is connected to a voltage lower than SGND node 204 .
  • the SGND node 204 is also in electrical communication with the input of a testing circuit, which, in this embodiment, comprises a comparator 208 for comparing the voltage on the SGND node 204 to a reference voltage V R applied at another input of the comparator 208 .
  • a precharge voltage 210 is applied to the SGND node 204 .
  • a switch 211 is interposed between precharge voltage 210 and SGND node 204 to turn the precharge voltage 210 on and off.
  • Reference voltage 212 is applied to an external reference of comparator 208 . Reference voltage 212 may be variable, as will be discussed further below.
  • the bank 202 eliminates the need for offline collection and analysis of t test versus resistance values as in the prior art. Instead, a desired resistor value is chosen according to a design parameter. A specification may require a resistance value of 300 K ⁇ or less for programming. In FIG. 2, for example, resistors R 1 and R 2 may have resistance values of 750 K ⁇ and 500 K ⁇ , respectively. If switches SR 1 and SR 2 are actuated substantially at the same time while the rest of the switches in the bank 202 are left deactuated, the total resistance of bank 202 is the desired resistance of 300 K ⁇ .
  • switch SB TM is electrically interposed between SGND or first supply node 302 and bank 202 .
  • the resistors R 1 , R 2 , R 3 , . . . R N are connected in series with switches SR 1 , SR 2 , SR 3 , . . . SR N between node 304 and node 306 .
  • Node 304 is connected through SB TM to SGND or first node 302 .
  • node 306 is connected to ground.
  • Reference voltage 212 is applied to an external reference of comparator 208 . Reference voltage 212 may be variable, as will be discussed further below.
  • Precharge voltage 210 is applied to SGND node 302 .
  • FIG. 6 shows a representative alternative resistance configuration 602 , which may be substituted for bank 202 without departing from the scope of the invention.
  • FIG. 6 shows a plurality of control resistors comprising a plurality of resistors R 1 , R 2 , R 3 , . . . R N , in series with a plurality of switches SR 1 , SR 2 , SR 3 , . . . SR N , as in bank 202 .
  • These control resistors are also connected in series with a parallel configuration of legs comprising further resistors and fuses in series.
  • switches SR 12 , SR 22 , SR 32 , . . . SR N2 are connected in series with resistors R 12 , R 22 , R 32 , . . . RN 2 , respectively.
  • switches SR 11 , SR 21 , SR 31 , . . . SR N1 are connected in series with resistors R 11 , R 21 , R 31 , . . . R N1 .
  • Legs 612 and 611 are connected in parallel with each other, and the parallel combination is connected in series with resistor R 1 and switch SR 1 .
  • Legs 622 and 621 are connected in parallel with each other, and the parallel combination is connected in series with resistor R 2 and switch SR 2 .
  • Legs 632 and 631 are connected in parallel with each other, and the parallel combination is connected in series with resistor R 3 and switch SR 3 .
  • Legs 6 N 2 and 6 N 1 are connected in parallel with each other, and the parallel combination is connected in series with resistor R N and switch SR N .
  • the SGND node 302 may be connected to a precharge voltage 402 through switch 403 to turn precharge voltage 402 on and off.
  • Second supply node 306 may be connected to a voltage greater than the precharge voltage.
  • the voltage of the node 304 charges in a manner consistent with an RC circuit.
  • Reference voltage 212 is applied to an external reference of comparator 208 .
  • Reference voltage 212 may be variable, as will be discussed further below.
  • the invention further provides for adjustment of test times through varying reference voltage V R .
  • Circuit 212 for accomplishing this ability to adjust the test times is shown in FIG. 5.
  • An embodiment of circuit 212 is connected to an external access to a variable reference in either of comparators 208 or 308 of the embodiments shown in FIGS. 2 - 4 , instead of the prior art hardwiring of the reference voltage of the comparators 208 or 308 to a particular voltage.
  • a comparator is connectable to a reference voltage V R , which may be a variable voltage source, through transistor 502 . While transistor 502 is shown as a p-channel transistor, any switching device or mechanism will also be acceptable without departing from the scope of the invention.
  • the reference in the comparator 30 is ordinarily permanently connected to some hardwired reference voltage which permits the comparator 30 to switch at a switch time period t fuse .
  • some hardwired reference voltage which permits the comparator 30 to switch at a switch time period t fuse .
  • the voltage to be 2.5 V
  • the switch time period t fuse to be equal to 40 nanoseconds when the fuse has a resistance of 300 K ⁇ .
  • V R can be changed to 3.0 V, permitting the comparator 208 or 308 to switch at a lower switch time period t fuse of for example 30 nanoseconds.
  • a time savings of 10 nanoseconds is achieved by varying the reference voltage of comparator 208 or 308 .
  • the process can be repeated with V R greater than 3.0 V, such as 3.5 V.
  • This new comparator reference voltage of 3.5 V may permit the comparator 208 or 308 to switch at a lower switch time period t fuse of for example 25 nanoseconds.
  • the process can again be repeated as desired or until the comparator 208 or 308 no longer switches for a higher reference voltage.
  • the comparator reference voltage in any of the embodiments shown in FIGS. 2 - 4 can be optimized such that the switch time period t fuse can be minimized. Because all fuses are tested, the present invention permits a significant amount of testing time to be saved.
  • Another embodiment of the invention is a method comprising the steps of determining a testing time for a control resistor, determining a testing time for a fuse, and comparing the testing time for the fuse against the testing time for the control resistor.
  • the step of determining the testing time for the control resistor comprises the steps of allowing to decay a voltage applied to a node, wherein the voltage applied to the node is also an input to a testing circuit, and waiting a time period for the voltage applied to the node to decay to a voltage less than or equal to a reference voltage of the testing circuit.
  • An embodiment 700 of the process of optimizing test times is now described generally in relation to FIG. 7.
  • the comparator reference voltage is initialized in step 702 .
  • a voltage is applied across a control resistor in step 704 .
  • This voltage is then allowed to decay in step 706 .
  • the time at which the comparator output switches is determined in step 708 .
  • the comparator reference voltage is adjusted in step 710 .
  • the voltage again is applied across the control resistor in step 712 , and the voltage is allowed to decay in step 714 .
  • the time at which the comparator output switches is determined in step 716 .
  • step 718 if the most recent switch time period is less than the previous switch time period, then a determination is made in step 720 as to whether a desired or preselected target switch time has been reached. If a desired target switch time has not been reached, the process is repeated starting with step 710 . If a desired target switch time has been reached, then in step 722 , the current comparator reference voltage and new switch time are used as parameters against which fuses are to be tested.
  • step 724 the previous switch time period and the previous value of the comparator reference voltage are used in performing subsequent testing of fuses in a memory device.
  • a precharge reference 210 is applied either to SGND node 204 or 302 in the embodiments of FIGS. 2 or 3 - 4 respectively while either node 206 or 306 in the embodiments of FIGS. 2 and 34 respectively is connected to ground, and wherein the actuation of a bank switch (such as SB 1 ) along with a fuse switch (such as SF 1 ) allows the voltage across a fuse (in this example, F 1 ), which is the voltage at SGND node 204 or 302 , to decay.
  • a bank switch such as SB 1
  • a fuse switch such as SF 1
  • the present invention applies equally well to a situation wherein the node 206 or 306 is at a higher potential than the SGND node 204 or 302 (i.e., the SGND node 204 or 302 is initialized to some voltage lower than node 206 or 306 ), and wherein the actuation of a bank switch (such as SB 1 ) along with a fuse switch (such as SF 1 ) causes the voltage across a fuse (in this example, F 1 ) to charge (instead of decay) in a manner consistent with an RC circuit.
  • the circuit embodiments of FIGS. 2 - 4 will operate in a fashion similar to what has been previously described for the situation where the voltage across a fuse is allowed to decay. Hence, even where the voltage across a fuse is caused to charge in a manner consistent with an RC circuit, testing circuit or comparator 208 or 308 still compares the voltage on the SGND node 204 or 302 against the respective comparator reference.
  • an external access to a reference in the comparator 208 or 308 may be provided, instead of the prior art configuration of hardwiring the reference voltage of the comparator 30 to a particular voltage.
  • the comparator 208 is connectable to a voltage V R , which may be a variable voltage source, through transistor 502 (FIG. 5).
  • comparator 308 is connectable to a voltage V R , which may be a variable voltage source, through transistor 502 ( Figure 502).
  • the reference of the comparator 30 is ordinarily permanently connected to some fixed reference voltage which permits the comparator 30 to switch at a switch time period t fuse .
  • some fixed reference voltage which permits the comparator 30 to switch at a switch time period t fuse .
  • V R can be changed, for example to 2.0 V, permitting the comparator 208 or 308 to switch at a lower switch time period t fuse of for example 30 nanoseconds.
  • a time savings of 10 nanoseconds is achieved by varying the reference voltage of the comparator 208 or 308 through circuit 212 .
  • the process can be repeated with V R less than 2.0 V, such as 1.5 V.
  • This new comparator reference voltage of 1.5 V may permit the comparator 30 to switch at a lower switch time period t fuse of say 25 nanoseconds.
  • the process can again be repeated as desired or until the comparator 208 or 308 no longer switches for a lower reference voltage.
  • the comparator reference voltage can be optimized such that the switch time period t fuse can be minimized. Because all fuses are tested, the present invention permits a significant amount of testing time to be saved.
  • FIG. 8 illustrates a simplified block diagram of a DRAM 100 .
  • the memory device can be coupled to a processor 112 such as a microprocessor of a personal computer.
  • the memory device 100 includes a memory array 114 having rows and columns of memory cells.
  • Column decoder 116 and row decoder 118 are provided to access the memory array in response to address signals provided by the processor 112 on address communication lines 128 .
  • Data communication is conducted via I/O buffer circuitry 122 and bi-directional data communication lines 126 (DQ).
  • Internal control circuitry 120 accesses the memory array in response to commands provided by the processor 112 on control lines 124 .
  • the control lines can include Row Address strobe (RAS*), Column Address Strobe (CAS*), Write Enable (WE*), Output Enable (OE*), and by using other conventional control signals (not shown) which are well known to those skilled in the art. It will be appreciated by those skilled in the art that the present invention is equally applicable to other types of memory devices including, but not limited to, SRAM, SDRAM, EDO, Burst EDO, and VRAM. Those skilled in the art will recognize that, in an alternate embodiment, DRAM memory array 114 may be accessed by a DRAM controller (not shown) instead of microprocessor 112 . Additional embodiments of the present invention may comprise a testing circuit, as described above, electrically connected to a memory such as memory 100 to test the system as has been described above. Another embodiment of the present invention is a memory such as memory 100 manufactured or provided with circuitry as described above to test the memory 100 .
  • FIG. 9 shows a computer system setup 150 in block diagram.
  • Computer system 150 typically includes processor 112 , memory such as memory 100 , monitor 152 , keyboard or other input device 154 , mouse or other pointing device 156 , and data storage (not shown) including but not limited to a hard drive, floppy drive, CD-ROM or DVD-ROM. Other components may be added to computer system 150 , as is well known in the art.
  • a computer system is electrically connected to a memory, the memory having electrically connected thereto a testing circuit such as those described above.
  • Still yet another embodiment of the present invention comprises a computer system such as computer system 150 provided with a memory having a memory testing circuit such as those described above electrically connected thereto.
  • An exemplary method embodiment for testing a fuse in an integrated circuit comprises determining a testing time for a control resistor, determining a testing time for the fuse, and comparing the testing time for the fuse against the testing time for the control resistor.
  • An exemplary method for determining a desired test time for a fuse comprises initializing a reference voltage in a testing circuit, applying a pre-charge voltage across the control resistor, determining the time at which the pre-charge voltage decays to a value less than the reference voltage in the testing circuit, adjusting the reference voltage if the determined decay time is greater than a preselected desired decay time, repeating the application of the pre-charge voltage across the control resistor to adjusting the reference voltage if necessary, and selecting the determined decay time as the test time.
  • An alternative exemplary method for determining a desired test time for a fuse comprises initializing a reference voltage in a testing circuit, applying a pre-charge voltage across the control resistor, determining the time at which the pre-charge voltage charges to a value greater than the reference voltage in the testing circuit, adjusting the reference voltage if the determined charge time is greater than a preselected desired charge time, repeating the application of the pre-charge voltage across the control resistor to adjusting the reference voltage as necessary, and selecting the determined charge time as the test time.
  • An exemplary circuit embodiment of the present invention for testing fuses in an integrated circuit comprises a bank of control resistors electrically interposed between a first supply node and a second supply node, and a testing circuit having an input and an access to a reference in the testing circuit, wherein the input of the testing circuit is in electrical communication with the first supply node.
  • the second supply node may be connected to a potential higher than the first supply node and the first node.
  • fuses and antifuses are one design choice, as well as the location of the fuses, and various methods of setting the fuses are well within the scope of the invention.
  • memory devices are comprised of multiple subarrays, each subarray having corresponding redundant rows and/or columns, or a bank of redundant rows and/or columns being provided for all the subarrays. The sizes and numbers of subarrays can also be varied without departing from the invention. Still further, other types of memory devices making use of redundant rows and/or columns of memory selectable by whatever method may make use of the present invention.

Abstract

A voltage is applied across a control resistor, and the voltage is caused to decay. The decay is monitored by a testing circuit such as a comparator. When the voltage across the control resistor has decayed to a value less than or equal to a reference voltage in the comparator, a switch time period is established. Fuses in a memory device are tested against the established switch time period. The fuses are tested in a similar fashion: a voltage is applied across the fuse being tested, and the voltage is caused to decay. The comparator monitors the decay of the voltage across the fuse. If the resistance value of a fuse being tested is within specification, the comparator changes its state at a time equal to or less than the switch time period established for the control resistor. Testing time for fuses can further be minimized by having an external access to the reference in the comparator. In establishing the switch time period by applying a voltage across the control resistor, the voltage of the reference in the comparator is adjusted to establish quicker switch time periods against which fuses are tested. In this manner, testing time is minimized.

Description

    FIELD OF THE INVENTION
  • The present invention relates to semiconductor based memory devices, and in particular to testing fuses in integrated memory circuits. [0001]
  • BACKGROUND OF THE INVENTION
  • As the number of electronic elements contained on semiconductor integrated circuits continues to increase, the problems of reducing and eliminating defects in the elements become more difficult. To achieve higher electronic element population densities, circuit designers strive to reduce the size of the individual elements to maximize available die real estate, to increase speed of operation, to increase circuit density per chip, and the like. The reduced size of individual elements, however, makes these elements increasingly susceptible to defects caused by material impurities during fabrication. These defects can be identified upon completion of the integrated circuit fabrication by testing procedures, either at the semiconductor chip level or after complete packaging. Scrapping or discarding defective circuits is economically undesirable, particularly if only a small number of elements are actually defective. [0002]
  • Relying on zero defects in the fabrication of integrated circuits is an unrealistic option. To reduce the amount of semiconductor scrap, redundant elements are provided on the circuit. If a primary element is determined to be defective, a redundant element can be substituted for the defective element. Substantial reductions in scrap can be achieved by using redundant elements. [0003]
  • One type of integrated circuit device which uses redundant circuit elements is memory integrated circuits, such as, for example, dynamic random access memories (DRAMs), static random access memories (SRAMs), video random access memories (VRAMs), erasable programmable read only memories (EPROMs), synchronous dynamic random access memories (SDRAMs), FLASH memories, and other memory types. Typical integrated memory circuits comprise millions of equivalent memory cells arranged in arrays of addressable rows and columns. The rows and columns of memory cells are the primary circuit elements of the integrated memory circuit. By providing redundant circuit elements, either as rows or columns, defective primary rows or columns can be replaced. [0004]
  • Because the individual primary circuit elements (rows or columns) of an integrated memory circuit are separately addressable, replacing a defective circuit element typically entails programming fuses to cause a redundant circuit element to respond to the address of the defective primary circuit element. This process is very effective for permanently replacing defective primary circuit elements. [0005]
  • In the case of DRAMs, for example, a particular memory cell is selected by first providing a unique row address of the row in which the particular memory cell is located and subsequently providing a unique column address of the column in which the particular memory cell is located. Redundancy circuitry must recognize the address of the defective primary circuit element and reroute all signals to the redundant circuit element when the address to the defective primary circuit element is presented by the user. Therefore, a number of fuses or antifuses are associated with each redundant circuit element. The possible combinations of programmed fuses corresponding to each redundant circuit element represent unique addresses of all primary circuit elements for which a corresponding redundant circuit element may be substituted. While antifuses are described, fuses will function equally as well in the circuit. [0006]
  • Antifuses are typically fabricated with a structure similar to that of a capacitor, such that two conductive electrical terminals are separated by a dielectric layer. In the unprogrammed state, in which the antifuse is fabricated, there is a high resistance between the terminals, while in the programmed state, there is low resistance. To program an antifuse, a large programming voltage is applied across the antifuse terminals, breaking down the interposed dielectric and forming a conductive link between the antifuse terminals. [0007]
  • All antifuses are tested to ensure that they are properly programmed. A prior art technique for testing antifuses is shown in FIG. 1, which shows two reference nodes, [0008] SGND node 10 and node 20. The SGND node 10 is also in electrical communication with the input of a testing circuit, which is a comparator 30 which compares a hard wired reference voltage to the voltage on the SGND node 10. A precharge voltage 40 is applied to the SGND node 10. A switch 45 is interposed between precharge voltage 40 and SGND node 10 to turn the precharge voltage 40 on and off. The node 20 is connected to ground. Antifuses 50 are electrically interposed between the SGND node 10 and the node 20.
  • Fuse F[0009] 1 is one of the fuses in bank B. In order to test whether a good program has been achieved for fuse F1, switch SB1 for the bank B1 is actuated while switch SF1 is enabled. Having both switch SB1 and switch SF 1 simultaneously actuated creates a direct path from SGND node 10 to node 20. Because the fuse F1 has resistance and the bus to which it is connected has capacitance, upon actuation of both switch SB1 and switch SF1, the voltage of SGND node 10 decays in a manner consistent with an RC circuit. Prior to the actuation of switch SB1 and switch SF1 output of the comparator 30 is in a tri-state condition; however, as soon as switch SB1 and switch SF1 are actuated, the output of comparator 30 switches low. If fuse F1 was properly programmed, the output of comparator 30 will switch back high at or before a switch time period tfuse. If the output of comparator 30 does not switch back high at or before switch time period tfuse, then fuse F1 was not properly programmed.
  • The switch time period t[0010] fuse is typically determined by performing the following steps for a statistically valid number of fuses. First, the resistance of a fuse is measured. Techniques for measuring resistance are well known in the art; however, one way of measuring fuse resistance is by applying a voltage across a fuse, measuring the resulting current through the fuse, and calculating the resistance using Ohm's law. Second, a measurement is taken of the time it takes from when both the bank switch (such as, for example, SBn or SB1) and the fuse switch (such as, for example, SF1, SF2, SFx, etc.) are actuated for the output of the comparator 30 (as shown in FIG. 1) to swing to the high state. As an example, if fuse F2 is being tested, both bank switch SB1 and fuse switch SF2 must be actuated. The measurement time obtained is referred to as a ttest value. Third, the individual ttest value for a particular fuse is plotted against the resistance value for such particular fuse, and this step is performed for all measured fuses. Fourth, a decision is made as to what resistance value is indicative of a fuse that has been programmed properly. For example, it may be decided that a resistance value of 300 KΩ or less indicated that the fuse being tested has been properly programmed. Finally, from the plot of ttest versus resistance, as described in the third step above, it is determined at or under which ttest value the comparator output switched for a majority of the fuses measured having resistance values of 300 KΩ or less.
  • The process of collecting and analyzing data for a statistically valid number of fuses can be lengthy. Accordingly, such process is performed offline. After data regarding fuse test times and resistance values are collected and analyzed, and a switch time period t[0011] fuse is established, individual fuses are then tested in accordance with the circuit shown in FIG. 1. This testing is performed during manufacturing or as the fuses are programmed.
  • Moreover, the [0012] comparator 30 has a reference 55 which, in the prior art, is hardwired to a particular voltage value. Hence, the switch time period tfuse is highly dependent on the voltage value to which the reference in the comparator 30 is connected. For example, suppose the reference in the comparator 30 is hardwired to 2.5 V, so that when the voltage level on SGND node 10 drops below 2.5 V the output of the comparator 30 switches high. It is possible for the output of the comparator 30 to switch even at a reference voltage greater than 2.5 V (e.g. 3.0 V), thus decreasing the testing time required. However, because the reference in the comparator 30 is hardwired to a particular voltage, it is difficult to change the reference voltage in the event tighter control over testing time is desired.
  • Accordingly, there is a need for testing fuses without having to collect sample points. There is further a need to make the process of testing fuses faster in order to save testing time during manufacture. [0013]
  • SUMMARY OF THE INVENTION
  • The present invention is directed to a method and circuit for testing fuses in memory integrated circuits such as those discussed above. One embodiment of the invention is a circuit comprising a test bank of control resistors and a testing circuit, wherein the bank of control resistors establishes a test period of all fuses being tested. In another aspect of the invention, the testing circuit comprises a comparator having a reference voltage for comparison to a node voltage, wherein an external access to the reference of the comparator is provided. This external access to the reference of the comparator permits the minimization of test times. [0014]
  • The step of determining the testing time for a fuse comprises the steps of allowing to decay the voltage applied to the node, and waiting a time period for the voltage applied to the node to decay to a voltage less than or equal to the reference voltage applied to the comparator. In another aspect of the invention, the method includes, after the step of comparing the testing time for the fuse against the testing time for the control resistor, the step of deciding whether the testing time for the fuse meets predetermined specification parameters based on the testing time for the control resistor. The use of the control resistor obviates the need for the prior art technique of collecting and analyzing data for a statistically valid number of fuses.[0015]
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 is a circuit diagram depicting a prior art technique for testing fuses in integrated memory circuits; [0016]
  • FIG. 2 is a circuit diagram showing an embodiment of the present invention; [0017]
  • FIG. 3 is a circuit diagram showing another embodiment of the present invention; [0018]
  • FIG. 4 is a circuit diagram showing yet another embodiment of the present invention; [0019]
  • FIG. 5 is a circuit diagram showing an embodiment of a variable reference voltage; [0020]
  • FIG. 6 is a representative circuit diagram showing an alternative resistance configuration; [0021]
  • FIG. 7 is a flowchart block diagram depicting a method of the present invention; [0022]
  • FIG. 8 is a block diagram of a memory to which embodiments of the present invention may be electrically connected; and [0023]
  • FIG. 9 is a perspective view of a typical computer system to which embodiments of the present invention may be electrically connected.[0024]
  • DESCRIPTION OF THE EMBODIMENTS
  • In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the spirit and scope of the present invention. The terms wafer and substrate used in the following description include any semiconductor-based structure having an exposed surface with which to form the integrated circuit structure of the invention. Wafer and substrate are used interchangeably to refer to semiconductor structures during processing, and may include other layers that have been fabricated thereupon. Both wafer and substrate include doped and undoped semiconductors, epitaxial semiconductor layers supported by a base semiconductor or insulator, as well as other semiconductor structures well known to one skilled in the art. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. [0025]
  • FIG. 2 depicts an [0026] embodiment 200 of the present invention. A bank 202 comprising a plurality of control resistors comprising a plurality of resistors R1, R2, R3, . . . RN, and a plurality of switches SR1, SR2, SR3, . . . SRN, is electrically interposed between SGND or first supply node 204 and a second supply node 206, which is connected to a voltage lower than SGND node 204. The SGND node 204 is also in electrical communication with the input of a testing circuit, which, in this embodiment, comprises a comparator 208 for comparing the voltage on the SGND node 204 to a reference voltage VR applied at another input of the comparator 208. A precharge voltage 210 is applied to the SGND node 204. A switch 211 is interposed between precharge voltage 210 and SGND node 204 to turn the precharge voltage 210 on and off. Reference voltage 212 is applied to an external reference of comparator 208. Reference voltage 212 may be variable, as will be discussed further below.
  • The [0027] bank 202 eliminates the need for offline collection and analysis of ttest versus resistance values as in the prior art. Instead, a desired resistor value is chosen according to a design parameter. A specification may require a resistance value of 300 KΩ or less for programming. In FIG. 2, for example, resistors R1 and R2 may have resistance values of 750 KΩ and 500 KΩ, respectively. If switches SR1 and SR2 are actuated substantially at the same time while the rest of the switches in the bank 202 are left deactuated, the total resistance of bank 202 is the desired resistance of 300 KΩ.
  • In another embodiment shown in FIG. 3, switch SB[0028] TM is electrically interposed between SGND or first supply node 302 and bank 202. The resistors R1, R2, R3, . . . RN are connected in series with switches SR1, SR2, SR3, . . . SRN between node 304 and node 306. Node 304 is connected through SBTM to SGND or first node 302. In one embodiment, node 306 is connected to ground. If switch SBTM is actuated with both switches SR1 and SR2 actuated, the voltage of the SGND node 302 starts to decay in a manner consistent with an RC circuit (the capacitance comes from the SGND node). Reference voltage 212 is applied to an external reference of comparator 208. Reference voltage 212 may be variable, as will be discussed further below. Precharge voltage 210 is applied to SGND node 302.
  • Prior to the actuation of switch SB[0029] TM and switches SR1 and SR2, the output of the comparator 308 is in a tri-state condition. However, as soon as switch SBTM and switches SR1 and SR2 are actuated, the output of comparator 308 switches low. At a switch time period tfuse, the output of comparator 308 will switch back high. The switch time period tfuse is then used as the standard against which the other fuses or antifuses will be measured during testing. In other words, if during testing of a fuse the output of comparator 308 remains low even after switch time period tfuse elapses, then such fuse was not properly programmed. Hence, the bank 202 eliminates the need for offline collection and analysis of ttest versus resistance values as in the prior art.
  • It should be understood also that various configurations for the provision of [0030] selectable resistance circuit 202 may be employed without departing from the scope of the invention. Such selectable resistance configurations are known to those skilled in the art. For example, but not by way of limitation, FIG. 6 shows a representative alternative resistance configuration 602, which may be substituted for bank 202 without departing from the scope of the invention. FIG. 6 shows a plurality of control resistors comprising a plurality of resistors R1, R2, R3, . . . RN, in series with a plurality of switches SR1, SR2, SR3, . . . SRN, as in bank 202. These control resistors are also connected in series with a parallel configuration of legs comprising further resistors and fuses in series.
  • To [0031] form legs 612, 622, 632, . . . 6N2, switches SR12, SR22, SR32, . . . SRN2 are connected in series with resistors R12, R22, R32, . . . RN2, respectively. To form legs 611, 621, 631, . . . 6N1, switches SR11, SR21, SR31, . . . SRN1, are connected in series with resistors R11, R21, R31, . . . RN1. Legs 612 and 611 are connected in parallel with each other, and the parallel combination is connected in series with resistor R1 and switch SR1. Legs 622 and 621 are connected in parallel with each other, and the parallel combination is connected in series with resistor R2 and switch SR2. Legs 632 and 631 are connected in parallel with each other, and the parallel combination is connected in series with resistor R3 and switch SR3. Legs 6N2 and 6N1 are connected in parallel with each other, and the parallel combination is connected in series with resistor RN and switch SRN.
  • In another [0032] embodiment 400 shown in FIG. 4, the SGND node 302 may be connected to a precharge voltage 402 through switch 403 to turn precharge voltage 402 on and off. Second supply node 306 may be connected to a voltage greater than the precharge voltage. In this embodiment, the voltage of the node 304 charges in a manner consistent with an RC circuit. Reference voltage 212 is applied to an external reference of comparator 208. Reference voltage 212 may be variable, as will be discussed further below.
  • The invention further provides for adjustment of test times through varying reference voltage V[0033] R. Circuit 212 for accomplishing this ability to adjust the test times is shown in FIG. 5. An embodiment of circuit 212 is connected to an external access to a variable reference in either of comparators 208 or 308 of the embodiments shown in FIGS. 2-4, instead of the prior art hardwiring of the reference voltage of the comparators 208 or 308 to a particular voltage. As illustrated in FIG. 5, a comparator is connectable to a reference voltage VR, which may be a variable voltage source, through transistor 502. While transistor 502 is shown as a p-channel transistor, any switching device or mechanism will also be acceptable without departing from the scope of the invention.
  • For example, in prior art FIG. 1, the reference in the [0034] comparator 30 is ordinarily permanently connected to some hardwired reference voltage which permits the comparator 30 to switch at a switch time period tfuse. As an example, assume the voltage to be 2.5 V, and the switch time period tfuse to be equal to 40 nanoseconds when the fuse has a resistance of 300 KΩ. Using external access circuit 212 by connecting it to a reference of either of comparators 208 or 308 in the embodiments of FIGS. 2-4, as provided by the present invention, VR can be changed to 3.0 V, permitting the comparator 208 or 308 to switch at a lower switch time period tfuse of for example 30 nanoseconds. Hence, a time savings of 10 nanoseconds is achieved by varying the reference voltage of comparator 208 or 308. The process can be repeated with VR greater than 3.0 V, such as 3.5 V. This new comparator reference voltage of 3.5 V may permit the comparator 208 or 308 to switch at a lower switch time period tfuse of for example 25 nanoseconds. The process can again be repeated as desired or until the comparator 208 or 308 no longer switches for a higher reference voltage. In this manner, the comparator reference voltage in any of the embodiments shown in FIGS. 2-4 can be optimized such that the switch time period tfuse can be minimized. Because all fuses are tested, the present invention permits a significant amount of testing time to be saved.
  • Although an iteration process has been described, one of ordinary skill in the art can appreciate that other techniques may be substituted for optimizing the switch time period t[0035] fuse without departing from the scope of the invention.
  • Another embodiment of the invention is a method comprising the steps of determining a testing time for a control resistor, determining a testing time for a fuse, and comparing the testing time for the fuse against the testing time for the control resistor. The step of determining the testing time for the control resistor comprises the steps of allowing to decay a voltage applied to a node, wherein the voltage applied to the node is also an input to a testing circuit, and waiting a time period for the voltage applied to the node to decay to a voltage less than or equal to a reference voltage of the testing circuit. [0036]
  • An [0037] embodiment 700 of the process of optimizing test times is now described generally in relation to FIG. 7. The comparator reference voltage is initialized in step 702. A voltage is applied across a control resistor in step 704. This voltage is then allowed to decay in step 706. The time at which the comparator output switches is determined in step 708. The comparator reference voltage is adjusted in step 710. The voltage again is applied across the control resistor in step 712, and the voltage is allowed to decay in step 714. The time at which the comparator output switches is determined in step 716. In step 718, if the most recent switch time period is less than the previous switch time period, then a determination is made in step 720 as to whether a desired or preselected target switch time has been reached. If a desired target switch time has not been reached, the process is repeated starting with step 710. If a desired target switch time has been reached, then in step 722, the current comparator reference voltage and new switch time are used as parameters against which fuses are to be tested.
  • Referring again to step [0038] 718, however, if the most recent switch time period is not less than the previous switch time period, in step 724 the previous switch time period and the previous value of the comparator reference voltage are used in performing subsequent testing of fuses in a memory device.
  • The above description discusses an embodiment in which a [0039] precharge reference 210 is applied either to SGND node 204 or 302 in the embodiments of FIGS. 2 or 3-4 respectively while either node 206 or 306 in the embodiments of FIGS. 2 and 34 respectively is connected to ground, and wherein the actuation of a bank switch (such as SB1) along with a fuse switch (such as SF1) allows the voltage across a fuse (in this example, F1), which is the voltage at SGND node 204 or 302, to decay. However, the present invention applies equally well to a situation wherein the node 206 or 306 is at a higher potential than the SGND node 204 or 302 (i.e., the SGND node 204 or 302 is initialized to some voltage lower than node 206 or 306), and wherein the actuation of a bank switch (such as SB1) along with a fuse switch (such as SF1) causes the voltage across a fuse (in this example, F1) to charge (instead of decay) in a manner consistent with an RC circuit. The circuit embodiments of FIGS. 2-4 will operate in a fashion similar to what has been previously described for the situation where the voltage across a fuse is allowed to decay. Hence, even where the voltage across a fuse is caused to charge in a manner consistent with an RC circuit, testing circuit or comparator 208 or 308 still compares the voltage on the SGND node 204 or 302 against the respective comparator reference.
  • In another embodiment, instead of allowing a decay in voltage to perform testing of a fuse, voltage across a fuse is caused to charge. The time it takes for the voltage across the fuse to reach a reference voltage in a testing circuit is compared against the time it takes for the voltage across a control resistor to charge up to the same reference voltage. A determination is then made as to whether the fuse is acceptable. This embodiment, where the voltage across a fuse is caused to charge in a manner consistent with an RC circuit, is also achieved with the [0040] external access circuit 212 to comparator reference by applying VR to the input of comparator 208 or 308 through transistor 502 as illustrated in FIG. 5.
  • In FIGS. [0041] 2-4, an external access to a reference in the comparator 208 or 308 may be provided, instead of the prior art configuration of hardwiring the reference voltage of the comparator 30 to a particular voltage. As illustrated in FIG. 2, the comparator 208 is connectable to a voltage VR, which may be a variable voltage source, through transistor 502 (FIG. 5). In FIGS. 3-4, comparator 308 is connectable to a voltage VR, which may be a variable voltage source, through transistor 502 (Figure 502).
  • By way of comparison, in the prior art the reference of the [0042] comparator 30 is ordinarily permanently connected to some fixed reference voltage which permits the comparator 30 to switch at a switch time period tfuse. As an example, assume the voltage to be 2.5 V, and the switch time period tfuse to be equal to 40 nanoseconds when the fuse has a resistance of 300 KΩ. With the external access circuit 212 to the comparator reference as provided by the present invention, VR can be changed, for example to 2.0 V, permitting the comparator 208 or 308 to switch at a lower switch time period tfuse of for example 30 nanoseconds. Hence, a time savings of 10 nanoseconds is achieved by varying the reference voltage of the comparator 208 or 308 through circuit 212. The process can be repeated with VR less than 2.0 V, such as 1.5 V. This new comparator reference voltage of 1.5 V may permit the comparator 30 to switch at a lower switch time period tfuse of say 25 nanoseconds. The process can again be repeated as desired or until the comparator 208 or 308 no longer switches for a lower reference voltage. In this manner, the comparator reference voltage can be optimized such that the switch time period tfuse can be minimized. Because all fuses are tested, the present invention permits a significant amount of testing time to be saved.
  • As to FIG. 7 and the steps enumerated therein, in a situation where the voltage across a fuse is caused to charge in a manner consistent with an RC circuit, the voltage across the control resistor is caused to charge, instead of allowing it to decay, in [0043] steps 706 and 714 (of FIG. 7). The other steps remain the same.
  • FIG. 8 illustrates a simplified block diagram of a [0044] DRAM 100. The memory device can be coupled to a processor 112 such as a microprocessor of a personal computer. The memory device 100 includes a memory array 114 having rows and columns of memory cells. Column decoder 116 and row decoder 118 are provided to access the memory array in response to address signals provided by the processor 112 on address communication lines 128. Data communication is conducted via I/O buffer circuitry 122 and bi-directional data communication lines 126 (DQ). Internal control circuitry 120 accesses the memory array in response to commands provided by the processor 112 on control lines 124. The control lines can include Row Address strobe (RAS*), Column Address Strobe (CAS*), Write Enable (WE*), Output Enable (OE*), and by using other conventional control signals (not shown) which are well known to those skilled in the art. It will be appreciated by those skilled in the art that the present invention is equally applicable to other types of memory devices including, but not limited to, SRAM, SDRAM, EDO, Burst EDO, and VRAM. Those skilled in the art will recognize that, in an alternate embodiment, DRAM memory array 114 may be accessed by a DRAM controller (not shown) instead of microprocessor 112. Additional embodiments of the present invention may comprise a testing circuit, as described above, electrically connected to a memory such as memory 100 to test the system as has been described above. Another embodiment of the present invention is a memory such as memory 100 manufactured or provided with circuitry as described above to test the memory 100.
  • FIG. 9 shows a [0045] computer system setup 150 in block diagram. Computer system 150 typically includes processor 112, memory such as memory 100, monitor 152, keyboard or other input device 154, mouse or other pointing device 156, and data storage (not shown) including but not limited to a hard drive, floppy drive, CD-ROM or DVD-ROM. Other components may be added to computer system 150, as is well known in the art. In yet another embodiment of the present invention, a computer system is electrically connected to a memory, the memory having electrically connected thereto a testing circuit such as those described above. Still yet another embodiment of the present invention comprises a computer system such as computer system 150 provided with a memory having a memory testing circuit such as those described above electrically connected thereto.
  • Conclusion
  • An exemplary method embodiment for testing a fuse in an integrated circuit comprises determining a testing time for a control resistor, determining a testing time for the fuse, and comparing the testing time for the fuse against the testing time for the control resistor. [0046]
  • An exemplary method for determining a desired test time for a fuse comprises initializing a reference voltage in a testing circuit, applying a pre-charge voltage across the control resistor, determining the time at which the pre-charge voltage decays to a value less than the reference voltage in the testing circuit, adjusting the reference voltage if the determined decay time is greater than a preselected desired decay time, repeating the application of the pre-charge voltage across the control resistor to adjusting the reference voltage if necessary, and selecting the determined decay time as the test time. [0047]
  • An alternative exemplary method for determining a desired test time for a fuse comprises initializing a reference voltage in a testing circuit, applying a pre-charge voltage across the control resistor, determining the time at which the pre-charge voltage charges to a value greater than the reference voltage in the testing circuit, adjusting the reference voltage if the determined charge time is greater than a preselected desired charge time, repeating the application of the pre-charge voltage across the control resistor to adjusting the reference voltage as necessary, and selecting the determined charge time as the test time. [0048]
  • An exemplary circuit embodiment of the present invention for testing fuses in an integrated circuit comprises a bank of control resistors electrically interposed between a first supply node and a second supply node, and a testing circuit having an input and an access to a reference in the testing circuit, wherein the input of the testing circuit is in electrical communication with the first supply node. [0049]
  • Further embodiments of the apparatus for testing fuses in an integrated circuit comprise a bank of control resistors electrically interposed between a first supply node and a second supply node, a testing circuit having an input and an access to a reference in the testing circuit, wherein the input of the testing circuit is in electrical communication with the first supply node, wherein the bank of control resistors comprises a plurality of elements connected in parallel and electrically interposed between a first node and the second supply node, wherein the first node is connected to a pre-charge voltage, and wherein the second supply node is connected to a potential lower than the first supply node and the first node, and wherein the elements comprise a first switching device connected in series with a control resistor. Alternatively, the second supply node may be connected to a potential higher than the first supply node and the first node. [0050]
  • It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. As previously mentioned, the use of fuses and antifuses are one design choice, as well as the location of the fuses, and various methods of setting the fuses are well within the scope of the invention. Further, it is well known that memory devices are comprised of multiple subarrays, each subarray having corresponding redundant rows and/or columns, or a bank of redundant rows and/or columns being provided for all the subarrays. The sizes and numbers of subarrays can also be varied without departing from the invention. Still further, other types of memory devices making use of redundant rows and/or columns of memory selectable by whatever method may make use of the present invention. [0051]

Claims (55)

What is claimed is:
1. A method for testing a fuse in an integrated circuit, the method comprising:
determining a testing time for a control resistor;
determining a testing time for the fuse; and
comparing the testing time for the fuse against the testing time for the control resistor.
2. The method of
claim 1
, wherein determining the testing time for the control resistor comprises:
applying a voltage to the control resistor; and
measuring a time period for the voltage to decay to a decayed voltage less than or equal to a reference voltage.
3. The method of
claim 2
, further comprising applying the decayed voltage to a comparator.
4. The method of
claim 1
, wherein determining the testing time for the fuse comprises:
applying a voltage to a fuse; and
measuring a time period for the voltage to decay to a decayed voltage less than or equal to a reference voltage.
5. The method of
claim 4
, further comprising applying the decayed voltage to a comparator.
6. The method of
claim 1
, wherein determining the testing time for the control resistor comprises:
applying a voltage to the control resistor; and
measuring a time period for the voltage to charge to a charged voltage greater than or equal to a reference voltage.
7. The method of
claim 6
, further comprising applying the charged voltage to a comparator.
8. The method of
claim 1
, wherein determining the testing time for the fuse comprises:
applying a voltage to a fuse; and
measuring a time period for the voltage to charge to a charged voltage greater than or equal to a reference voltage.
9. The method of
claim 8
, further comprising applying the charged voltage to a comparator.
10. The method of
claim 1
, further comprising selecting a value of the control resistor.
11. The method of
claim 1
, further comprising deciding, after comparing, whether the testing time for the fuse meets specification parameters based on the testing time for the control resistor.
12. A circuit for testing fuses in an integrated circuit comprising:
a control resistor electrically interposed between a first supply node and a second supply node; and
a testing circuit having an input and an access to a reference in the testing circuit,
wherein the input of the testing circuit is in electrical communication with the first supply node.
13. The circuit for testing fuses of
claim 12
, wherein the first supply node is connected to a precharge voltage, and wherein the second supply node is connected to a potential lower than the first supply node.
14. The circuit for testing fuses of
claim 13
, wherein the second supply node is connected to ground.
15. The circuit for testing fuses of
claim 12
, wherein the first supply node is connected to a precharge voltage, and wherein the second supply node is connected to a potential higher than the first supply node.
16. The circuit for testing fuses of
claim 12
, wherein the testing circuit comprises a comparator.
17. A circuit for testing fuses in an integrated circuit comprising:
a bank of selectable control resistors electrically interposed between a first supply node and a second supply node; and
a testing circuit having an input and an access to a reference in the testing circuit,
wherein the input of the testing circuit is in electrical communication with the first supply node.
18. The circuit for testing fuses of
claim 17
, wherein the bank of control resistors comprises a plurality of elements connected in parallel and electrically interposed between a first node and the second supply node.
19. The circuit for testing fuses of
claim 18
, wherein the first node is connected to a pre-charge voltage, and wherein the second supply node is connected to a potential lower than the first supply node and the first node.
20. The circuit for testing fuses of
claim 18
, wherein the elements comprise a first switching device connected in series with a control resistor.
21. The circuit for testing fuses of
claim 19
, and further comprising:
a second switching device electrically interposed between the first supply node and the first node.
22. The circuit for testing fuses of
claim 21
, wherein the second switching device is a transistor.
23. The circuit for testing fuses of
claim 21
, wherein the first switching device is a transistor.
24. A circuit for testing fuses in an integrated circuit comprising:
a bank of control resistors electrically interposed between a first supply node and a second supply node;
a testing circuit having an input and an access to a reference in the testing circuit,
wherein the input of the testing circuit is in electrical communication with the first supply node; and
wherein the bank of control resistors comprises a plurality of elements connected in parallel and electrically interposed between a first node and the second supply node, wherein the second supply node is connected to a potential higher than the first supply node and the first node, and wherein the elements comprise a first switching device connected in series with a control resistor.
25. The circuit for testing fuses of
claim 24
, and further comprising:
a second switching device electrically interposed between the first supply node and the first node.
26. The circuit for testing fuses of
claim 24
, wherein the first switching device is a transistor.
27. The circuit for testing fuses of
claim 26
, wherein the second switching device is a transistor.
28. A method for determining a desired test time for fuses, the method comprising:
initializing a reference voltage in a testing circuit;
applying a pre-charge voltage across a control resistor;
allowing the pre-charge voltage to decay;
determining a first time at which the pre-charge voltage has decayed to a value less than the reference voltage in the testing circuit;
adjusting the reference voltage in the testing circuit to obtain an updated reference voltage;
applying the pre-charge voltage across the control resistor;
allowing the pre-charge voltage to decay;
determining a second time at which the pre-charge voltage has decayed to a value less than the reference voltage in the testing circuit;
repeating adjusting through determining a second time if the second time is less than the first time; and
selecting the first time as the desired test time.
29. The method of
claim 28
, further comprising applying the pre-charge voltage to an input of a comparator.
30. The method of
claim 28
, further comprising selecting a value of the control resistor.
31. A method for determining a desired test time for fuses, the method comprising:
initializing a reference voltage in a testing circuit;
applying a voltage across a control resistor;
causing the voltage across the control resistor to charge;
determining a first time at which the voltage across the control resistor has increased to a value greater than the reference voltage in the testing circuit;
adjusting the reference voltage in the testing circuit to obtain an updated reference voltage;
applying a voltage across the control resistor;
causing the voltage across the control resistor to charge;
determining a second time at which the voltage across the control resistor has increased to a value greater than the reference voltage in the testing circuit;
repeating adjusting through determining a second time if the second time is less than the first time; and
selecting the first time as the desired test time.
32. The method of
claim 31
, further comprising applying the voltage across the control resistor to an input of a comparator.
33. The method of
claim 31
, further comprising selecting a value of the control resistor.
34. A method for determining a desired test time for a fuse, comprising:
initializing a reference voltage in a testing circuit;
applying a pre-charge voltage across the control resistor;
determining the time at which the pre-charge voltage decays to a value less than the reference voltage in the testing circuit;
adjusting the reference voltage if the determined decay time is greater than a preselected desired decay time;
repeating applying a pre-charge voltage through adjusting the reference voltage so long as the reference voltage was adjusted; and
selecting the determined decay time as the test time.
35. The method of
claim 34
, and further comprising applying the pre-charge voltage to an input of a comparator.
36. The method of
claim 34
, and further comprising selecting a value of the control resistor.
37. A method for determining a desired test time for a fuse, comprising:
initializing a reference voltage in a testing circuit;
applying a pre-charge voltage across the control resistor;
determining the time at which the pre-charge voltage charges to a value greater than the reference voltage in the testing circuit;
adjusting the reference voltage if the determined charge time is greater than a preselected desired charge time;
repeating applying a pre-charge voltage through adjusting the reference voltage so long as the reference voltage was adjusted; and
selecting the determined charge time as the test time.
38. The method of
claim 37
, and further comprising applying the pre-charge voltage to an input of a comparator.
39. The method of
claim 37
, and further comprising selecting a value of the control resistor.
40. A circuit for testing fuses in an integrated circuit comprising:
at least one bank of at least one fuse electrically interposed between a first supply node and a second supply node; and
a testing circuit having an input and an access to a reference in the testing circuit,
wherein the input of the testing circuit is in electrical communication with the first supply node.
41. The circuit for testing fuses of
claim 40
, wherein the testing circuit comprises a comparator.
42. The circuit for testing fuses of
claim 40
, wherein the at least one bank of at least one fuse comprises a plurality of elements connected in parallel and electrically interposed between a first node and the second supply node, wherein the second supply node is connected to a potential lower than the first supply node, and wherein the elements comprise a first switching device connected in series with a fuse.
43. The circuit for testing fuses of
claim 42
, and further comprising:
a second switching device electrically interposed between the first supply node and the first node.
44. The circuit for testing fuses of
claim 42
, wherein the first switching device is a transistor.
45. The circuit for testing fuses of
claim 43
, wherein the second switching device is a transistor.
46. The circuit for testing fuses of
claim 40
, wherein the at least one bank of at least one fuse comprises a plurality of elements connected in parallel and electrically interposed between a first node and the second supply node, wherein the second supply node is connected to a potential higher than the first supply node, and wherein the elements comprise a first switching device connected in series with a fuse.
47. The circuit for testing fuses of
claim 46
, and further comprising:
a second switching device electrically interposed between the first supply node and the first node.
48. The circuit for testing fuses of
claim 46
, wherein the first switching device is a transistor.
49. The circuit for testing fuses of
claim 47
, wherein the second switching device is a transistor.
50. A circuit for testing fuses, comprising:
a bank of control resistors electrically interposed between a first supply node and a second supply node;
a testing circuit comprising a comparator having an input and an access to a reference in the testing circuit, wherein the input of the testing circuit is in electrical communication with the first supply node;
wherein the bank of control resistors comprises a plurality of elements connected in parallel and electrically interposed between a first node and the second supply node, and wherein the elements comprise a first switching device connected in series with a fuse; and
a second switching device electrically interposed between the first supply node and the first node.
51. The circuit for testing fuses of
claim 50
, wherein the second supply node is connected to a potential lower than the first supply node.
52. The circuit for testing fuses of
claim 50
, wherein the second supply node is connected to a potential higher than the first supply node.
53. A circuit for testing fuses, comprising:
a bank of control resistors electrically interposed between a first supply node and a second supply node;
a testing circuit comprising a comparator having first and second inputs, wherein the first input of the testing circuit is in electrical communication with the first supply node;
a variable reference voltage source electrically connected to the second input of the comparator;
wherein the bank of control resistors comprises a plurality of elements connected in parallel and electrically interposed between a first node and the second supply node, and wherein the elements comprise a first switching device connected in series with a fuse; and
a second switching device electrically interposed between the first supply node and the first node.
54. A integrated circuit, comprising:
an array of memory cells; and
an electric circuit, electrically connected to the array of memory cells, the electric circuit comprising:
a bank of control resistors electrically interposed between a first supply node and a second supply node; and
a testing circuit having an input and an access to a reference in the testing circuit, wherein the input of the testing circuit is in electrical communication with the first supply node.
55. A computer system having a memory, comprising:
an electric circuit electrically connected to the memory, the electric circuit comprising:
a bank of control resistors electrically interposed between a first supply node and a second supply node; and
a testing circuit having an input and an access to a reference in the testing circuit, wherein the input of the testing circuit is in electrical communication with the first supply node.
US09/854,541 1998-09-03 2001-05-14 Apparatus and method for testing fuses Expired - Fee Related US6410352B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US09/854,541 US6410352B2 (en) 1998-09-03 2001-05-14 Apparatus and method for testing fuses

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US09/146,688 US6424161B2 (en) 1998-09-03 1998-09-03 Apparatus and method for testing fuses
US09/854,541 US6410352B2 (en) 1998-09-03 2001-05-14 Apparatus and method for testing fuses

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
US09/146,688 Division US6424161B2 (en) 1998-09-03 1998-09-03 Apparatus and method for testing fuses

Publications (2)

Publication Number Publication Date
US20010034070A1 true US20010034070A1 (en) 2001-10-25
US6410352B2 US6410352B2 (en) 2002-06-25

Family

ID=22518533

Family Applications (3)

Application Number Title Priority Date Filing Date
US09/146,688 Expired - Lifetime US6424161B2 (en) 1998-09-03 1998-09-03 Apparatus and method for testing fuses
US09/854,541 Expired - Fee Related US6410352B2 (en) 1998-09-03 2001-05-14 Apparatus and method for testing fuses
US10/179,543 Expired - Fee Related US6762608B2 (en) 1998-09-03 2002-06-25 Apparatus and method for testing fuses

Family Applications Before (1)

Application Number Title Priority Date Filing Date
US09/146,688 Expired - Lifetime US6424161B2 (en) 1998-09-03 1998-09-03 Apparatus and method for testing fuses

Family Applications After (1)

Application Number Title Priority Date Filing Date
US10/179,543 Expired - Fee Related US6762608B2 (en) 1998-09-03 2002-06-25 Apparatus and method for testing fuses

Country Status (1)

Country Link
US (3) US6424161B2 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6479308B1 (en) * 2001-12-27 2002-11-12 Formfactor, Inc. Semiconductor fuse covering
US20060258140A1 (en) * 2003-10-23 2006-11-16 Armin Fischer Integrated circuit with additional mini-pads connected by an under-bump metallization and method for production thereof
US20140184239A1 (en) * 2012-12-27 2014-07-03 SK Hynix Inc. Semiconductor device with fuse sensing circuit
US20140368226A1 (en) * 2013-06-17 2014-12-18 Lapis Semiconductor Co., Ltd. Semiconductor device and test method
CN110178094A (en) * 2017-01-03 2019-08-27 吉非迪亚有限公司 Timer

Families Citing this family (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6420262B1 (en) 2000-01-18 2002-07-16 Micron Technology, Inc. Structures and methods to enhance copper metallization
DE10119080B4 (en) * 2001-04-19 2005-05-04 Acam-Messelectronic Gmbh Method and switching arrangement for resistance measurement
US6806107B1 (en) * 2003-05-08 2004-10-19 Taiwan Semiconductor Manufacturing Company, Ltd. Electrical fuse element test structure and method
US6897674B2 (en) * 2003-06-30 2005-05-24 International Business Machines Corporation Adaptive integrated circuit based on transistor current measurements
JP2006012211A (en) * 2004-06-22 2006-01-12 Toshiba Corp Semiconductor integrated circuit
SI22025A (en) * 2005-03-21 2006-10-31 Metrel Merilna In Regulacijska Oprema D.D. Procedure for assessing the suitability level of safety devices
KR100757411B1 (en) * 2006-02-03 2007-09-11 삼성전자주식회사 Voltage resetting circuit for semiconductor memory device using option fuse circuit and voltage resetting method thereof
US7170299B1 (en) * 2006-02-15 2007-01-30 International Business Machines Corporation Electronic fuse blow mimic and methods for adjusting electronic fuse blow
JP2007218805A (en) * 2006-02-17 2007-08-30 Advantest Corp Measuring device and method
US7915916B2 (en) * 2006-06-01 2011-03-29 Micron Technology, Inc. Antifuse programming circuit with snapback select transistor
CN101226217B (en) * 2007-01-18 2010-10-06 宝山钢铁股份有限公司 Instrument for detecting breaking characteristic of current limiting fuse
US7889588B2 (en) * 2008-01-08 2011-02-15 Globalfoundries Inc. Circuit having gate oxide protection for low voltage fuse reads and high voltage fuse programming
KR100949264B1 (en) * 2008-06-10 2010-03-25 주식회사 하이닉스반도체 Monitoring circuit for semiconductor device
JP2010206114A (en) * 2009-03-05 2010-09-16 Renesas Electronics Corp Method of testing electric fuse, and electric fuse circuit
US8189419B2 (en) * 2009-07-06 2012-05-29 International Business Machines Corporation Apparatus for nonvolatile multi-programmable electronic fuse system
US7932738B1 (en) * 2010-05-07 2011-04-26 Power Integrations, Inc. Method and apparatus for reading a programmable anti-fuse element in a high-voltage integrated circuit
JP5686698B2 (en) 2011-08-05 2015-03-18 ルネサスエレクトロニクス株式会社 Semiconductor device
KR102133356B1 (en) * 2014-02-24 2020-07-13 에스케이하이닉스 주식회사 Semiconductor device and operation method for the same
US9456481B2 (en) * 2014-02-25 2016-09-27 Earl W. McCune, Jr. High-efficiency, wide dynamic range dimming for solid-state lighting
JP6314845B2 (en) * 2015-01-08 2018-04-25 株式会社オートネットワーク技術研究所 Electrical junction box
US11906560B2 (en) * 2021-12-08 2024-02-20 Nanya Technology Corporation System and method of measuring fuse resistance and non-transitory computer readable medium

Family Cites Families (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2061674A1 (en) 1969-12-30 1971-07-01 Honeywell Inf Systems Test procedure for checking electronic memories
US4191996A (en) 1977-07-22 1980-03-04 Chesley Gilman D Self-configurable computer and memory system
US4290013A (en) 1979-06-22 1981-09-15 Genrad, Inc. Method of and apparatus for electrical short testing and the like
US4503538A (en) 1981-09-04 1985-03-05 Robert Bosch Gmbh Method and system to recognize change in the storage characteristics of a programmable memory
US4519076A (en) 1981-12-28 1985-05-21 National Semiconductor Corporation Memory core testing system
DE3276399D1 (en) 1982-09-22 1987-06-25 Itt Ind Gmbh Deutsche Electrically programmable memory matrix
US4701695A (en) * 1983-12-22 1987-10-20 Monolithic Memories, Inc. Short detector for PROMS
US4814646A (en) 1985-03-22 1989-03-21 Monolithic Memories, Inc. Programmable logic array using emitter-coupled logic
JPS62114200A (en) 1985-11-13 1987-05-25 Mitsubishi Electric Corp Semiconductor memory device
EP0264893B1 (en) * 1986-10-20 1995-01-18 Nippon Telegraph And Telephone Corporation Semiconductor memory
US4841286A (en) 1988-02-08 1989-06-20 Honeywell Inc. Apparatus and method for detection of an open thermocouple in a process control network
US5202639A (en) 1989-01-09 1993-04-13 Schlumberger Technologies Limited Method and apparatus for testing analogue circuits
US4969124A (en) 1989-03-07 1990-11-06 National Semiconductor Corporation Method for vertical fuse testing
US5095274A (en) * 1989-09-22 1992-03-10 Analog Devices, Inc. Temperature-compensated apparatus for monitoring current having controlled sensitivity to supply voltage
US5051691A (en) 1990-09-13 1991-09-24 Samsung Semiconductor, Inc. Zero power dissipation laser fuse signature circuit for redundancy in vlsi design
US5113134A (en) 1991-02-28 1992-05-12 Thomson, S.A. Integrated test circuit for display devices such as LCD's
US5161387A (en) 1991-04-26 1992-11-10 American Standard Inc. Method and apparatus for configuring and controlling a load
US5206583A (en) * 1991-08-20 1993-04-27 International Business Machines Corporation Latch assisted fuse testing for customized integrated circuits
US5262994A (en) * 1992-01-31 1993-11-16 Sgs-Thomson Microelectronics, Inc. Semiconductor memory with a multiplexer for selecting an output for a redundant memory access
US5400343A (en) 1992-02-28 1995-03-21 Intel Corporation Apparatus and method for defective column detection for semiconductor memories
US5323377A (en) 1992-11-27 1994-06-21 Chen Zhi Q Electrical data recording and retrieval based on impedance variation
US5579326A (en) * 1994-01-31 1996-11-26 Sgs-Thomson Microelectronics, Inc. Method and apparatus for programming signal timing
US5635854A (en) 1994-05-24 1997-06-03 Philips Electronics North America Corporation Programmable logic integrated circuit including verify circuitry for classifying fuse link states as validly closed, validly open or invalid
US5502395A (en) 1994-05-25 1996-03-26 Allen; William J. Method for programming antifuses for reliable programmed links
US5612623A (en) 1994-05-27 1997-03-18 Nippondenso Co., Ltd. Failure diagnostic apparatus and method for a resistor element
EP0745859B1 (en) * 1995-05-31 2004-10-27 STMicroelectronics, Inc. Configurable probe pads to facilitate parallel testing of integrated circuit devices
JPH10125742A (en) 1996-10-22 1998-05-15 Mitsubishi Electric Corp Method of inspecting semiconductor integrated circuit and semiconductor integrated circuit
US6185705B1 (en) * 1997-03-07 2001-02-06 Micron Technology, Inc. Method and apparatus for checking the resistance of programmable elements
US5952833A (en) * 1997-03-07 1999-09-14 Micron Technology, Inc. Programmable voltage divider and method for testing the impedance of a programmable element
JPH11126498A (en) 1997-10-22 1999-05-11 Toshiba Corp Dynamic semiconductor memory
KR100735440B1 (en) * 1998-02-13 2007-10-24 로무 가부시키가이샤 Semiconductor device and magnetic disk device
JP2000132990A (en) 1998-10-27 2000-05-12 Fujitsu Ltd Redundant judging circuit, semiconductor memory apparatus and redundant judge method

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070132478A1 (en) * 2001-12-27 2007-06-14 Formfactor, Inc. Semiconductor Fuse Covering
US20030124750A1 (en) * 2001-12-27 2003-07-03 Eldridge Benjamin N. Semiconductor fuse covering
US6479308B1 (en) * 2001-12-27 2002-11-12 Formfactor, Inc. Semiconductor fuse covering
US7179662B2 (en) 2001-12-27 2007-02-20 Formfactor, Inc. Semiconductor fuse covering
US20110140236A1 (en) * 2003-10-23 2011-06-16 Armin Fischer Integrated Circuit with Pads Connected by an Under-Bump Metallization and Method for Production Thereof
US7919363B2 (en) * 2003-10-23 2011-04-05 Infineon Technologies Ag Integrated circuit with additional mini-pads connected by an under-bump metallization and method for production thereof
US20060258140A1 (en) * 2003-10-23 2006-11-16 Armin Fischer Integrated circuit with additional mini-pads connected by an under-bump metallization and method for production thereof
US8487453B2 (en) 2003-10-23 2013-07-16 Infineon Technologies Ag Integrated circuit with pads connected by an under-bump metallization and method for production thereof
US20140184239A1 (en) * 2012-12-27 2014-07-03 SK Hynix Inc. Semiconductor device with fuse sensing circuit
US20140368226A1 (en) * 2013-06-17 2014-12-18 Lapis Semiconductor Co., Ltd. Semiconductor device and test method
CN104240770A (en) * 2013-06-17 2014-12-24 拉碧斯半导体株式会社 Semiconductor device and test method
JP2015001995A (en) * 2013-06-17 2015-01-05 ラピスセミコンダクタ株式会社 Semiconductor device and test method
US9368227B2 (en) * 2013-06-17 2016-06-14 Lapis Semiconductor Co., Ltd. Semiconductor device and test method
CN110178094A (en) * 2017-01-03 2019-08-27 吉非迪亚有限公司 Timer

Also Published As

Publication number Publication date
US6762608B2 (en) 2004-07-13
US20020163343A1 (en) 2002-11-07
US6410352B2 (en) 2002-06-25
US20020003425A1 (en) 2002-01-10
US6424161B2 (en) 2002-07-23

Similar Documents

Publication Publication Date Title
US6410352B2 (en) Apparatus and method for testing fuses
US8917533B2 (en) Circuit and system for testing a one-time programmable (OTP) memory
US5724282A (en) System and method for an antifuse bank
US5838625A (en) Anti-fuse programming path
JP2557160B2 (en) Low voltage programmable storage element
JP2909328B2 (en) Field programmable gate array
US6128241A (en) Repair circuit of semiconductor memory device using anti-fuse
US20030123207A1 (en) Programmable element programmed by changes in resistance due to phase transition
US5815429A (en) Antifuse programming method and apparatus
JPH08213483A (en) Programmable semiconductor memory
KR20000048507A (en) Method and apparatus for providing external access to internal integrated circuit test circuits
US6356496B1 (en) Resistor fuse
US6317370B2 (en) Timing fuse option for row repair
US20060092726A1 (en) Memory redundancy programming
US9356604B2 (en) Integrated circuit and method for manufacturing the same
US5297087A (en) Methods and devices for accelerating failure of marginally defective dielectric layers
US7304485B2 (en) Analysis of the quality of contacts and vias in multi-metal fabrication processes of semiconductor devices, method and test chip architecture
US5923672A (en) Multipath antifuse circuit
US20020027815A1 (en) Cancellation of redundant elements with a cancel bank
JPH04290458A (en) Semiconductor device
US6154410A (en) Method and apparatus for reducing antifuse programming time
GB2349249A (en) Repair circuit of a semiconductor memory device
TWI382425B (en) Test system for identifying defects and method of operating the same
JPS60137000A (en) Semiconductor memory integrated circuit
JP4173763B2 (en) Semiconductor device

Legal Events

Date Code Title Description
FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Expired due to failure to pay maintenance fee

Effective date: 20140625