US20050016682A1 - Method of setting etching parameters and system therefor - Google Patents
Method of setting etching parameters and system therefor Download PDFInfo
- Publication number
- US20050016682A1 US20050016682A1 US10/893,275 US89327504A US2005016682A1 US 20050016682 A1 US20050016682 A1 US 20050016682A1 US 89327504 A US89327504 A US 89327504A US 2005016682 A1 US2005016682 A1 US 2005016682A1
- Authority
- US
- United States
- Prior art keywords
- pattern
- etching
- unit
- workmanship
- electron beam
- 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.)
- Abandoned
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing 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
- H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
- H01L21/31116—Etching inorganic layers by chemical means by dry-etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
- H01L21/321—After treatment
- H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
- H01L21/32133—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only
- H01L21/32135—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only
- H01L21/32136—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by vapour etching only using plasmas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Definitions
- the present invention relates to a method of setting optimal etching parameters in a semiconductor manufacturing process and a system therefor. More specifically, the present invention relates to a system that picks up an image of a pattern formed on a wafer, represents workmanship of the pattern quantitatively, performs etching parameter correction for reducing an amount of deviation between a quantitative value of the workmanship and a target etching pattern, and realizes setting for optimal etching parameters, and a performance evaluation system that evaluates performance of etching.
- etching parameters a gas flowrate, a pressure, a voltage, electric power, temperature, time, etc.
- etching parameters a gas flowrate, a pressure, a voltage, electric power, temperature, time, etc.
- etching parameters which are suitable for a quality of material of an etching object and an etching shape, with a help of experiences in the past and intuition on the basis of characteristics, which have been obtained through experiments, concerning the quality of material of the etching object and characteristics of an etching apparatus being used.
- step 202 the person performs etching with the etching parameters determined in step 201 .
- step 203 the person observes a pattern on a wafer, which is formed by the etching, with a scanning electron microscope (SEM) or the like to measure the etching pattern.
- step 204 the person judges manually whether desired etching performance is obtained on the basis of a measurement value obtained in step 203 . If it can be judged that a result of the etching is satisfactory, the person determines etching parameters.
- step 205 the person performs correction for the etching parameters, which brings etching performance close to the desired etching performance, on the basis of experiences in the past. Then, the person returns to step 202 and performs etching again with etching parameters set anew.
- the person determines etching parameters most suitable for obtaining the desired etching performance.
- the present invention has been devised in view of these problems, and it is an object of the present invention to provide a method of setting optimal etching parameters for performing desired etching and a system therefor.
- the present invention provides a method of setting parameters for etching, which includes: acquiring an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; processing the acquired electron beam image of the pattern formed on the surface of the wafer to judge workmanship of the pattern; presenting a result of judging the workmanship to a user; calculating corrected values of etching parameters for the etching apparatus on the basis of the result of judging the workmanship; and sending the calculated corrected value to the etching apparatus, and a system for the method.
- the present invention provides a method of setting parameters for etching, which includes: acquiring an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; processing the acquired electron beam image of the pattern formed on the surface of the wafer to extract a characteristic amount of the pattern; comparing the extracted characteristic amount of the pattern with data set in advance to judge workmanship of the pattern; presenting a result of judging the workmanship to a user; and calculating corrected values of etching parameters for the etching apparatus on the basis of the result of judging the workmanship, and a system for the method.
- FIG. 1 is a diagram showing a system for setting optimal etching parameters according to the present invention
- FIG. 2 is a diagram showing a conventional method
- FIG. 3 is a conceptual diagram showing the system for setting optimal etching parameters
- FIGS. 4A and 4B are diagrams showing examples of characteristics of etching performance
- FIG. 5 is a flow diagram of processing for deriving an etching performance quantitative value
- FIG. 6 is a conceptual diagram showing a system for setting optimal etching parameters in a mass production process
- FIG. 7 is a diagram showing a structure of a scanning electron microscope (SEM).
- FIG. 8 is a diagram showing an example of GUI display of an etching performance quantitative value
- FIG. 9 is a flow diagram of processing for creating an optimal parameter calculation model
- FIG. 10 is a conceptual diagram showing a method of changing parameters
- FIG. 11 is a flow diagram of processing for setting optimal etching parameters
- FIG. 12 is a flow diagram of correction for the optimal parameter calculation model in a mass production process.
- FIG. 13 is a diagram showing a structure of a scanning electron microscope (SEM) that is capable of acquiring a tilt image.
- SEM scanning electron microscope
- FIG. 1 shows a system configuration for automating parameter setting at the time of an etching process in semiconductor manufacturing in accordance with an embodiment of the present invention.
- This system includes an etching apparatus 1 , a scanning electron microscope (SEM) 2 that picks up images of an etching pattern, and a computer 3 including a processing unit 4 , which performs image processing and optimal etching parameter derivation processing, and a storage 5 , which saves etching pattern images, etching parameters, and the like.
- the respective components are connected by a bus 6 .
- FIG. 3 shows a flow of processing of this system.
- step 301 a modeled relation between various image characteristic amounts, which are derived from electron beam images of etching patterns that are formed when etching is performed by changing etching parameters (a gas flow rate, a pressure, wafer temperature, a coil magnetic field, etc.) in various ways, and the etching parameters are prepared in a preliminary experiment (hereinafter referred to as an optimal parameter calculation model).
- an etching target value for an etching pattern to be formed by etching is set.
- step 303 initial etching parameters are set using the optimal parameter calculation model prepared in advance.
- step 304 etching is performed on the basis of the etching parameters set in step 303 .
- step 305 an image of an etching pattern on a wafer formed by the etching is picked up by a scanning electron microscope (SEM) or the like.
- step 306 a performance value of the etching is calculated by image processing with respect to the image obtained in step 305 .
- step 307 it is judged whether the obtained etching performance value satisfies the etching target value. If the etching performance value satisfies the etching target value, an etching recipe at that point is set as optimal etching parameters for the etching target value.
- step 308 an etching parameter corrected value for bringing an etching result close to the target etching value is calculated on the basis of the optimal parameter calculation model.
- step 309 optimal etching parameters are set on the basis of the calculated corrected value. Then, etching is performed again with an etching recipe set anew (the processing is returned to step 304 ).
- FIG. 9 is a diagram showing processing to establishing an optimal parameter calculation model.
- items of a target etching performance quantitative value are A, B, and C
- items of etching parameters to be set in an etching apparatus are a, b, c, d, e, and f.
- A, B, and C are, for example, line edge roughness, a line width, a contact hole diameter, a hole roundness, and a characteristic amount of a contact hole bottom pattern
- a, b, c, d, e, and f are, for example, a gas flow rate, a pressure, a voltage, electric power, temperature, and time.
- step 901 an evaluation experiment using, for example, a Taguchi method is performed to find parameters, which affect in-plane evenness in an etching process, among the etching parameters.
- the etching parameters affecting in-plane evenness are excluded from controllable parameters (e.g., d, e, and f). These parameters are always fixed as fixed etching parameters, whereby evenness on a wafer is prevented from being ruined.
- step 903 experiment data necessary for the derivation of an optimal parameter calculation model (experiment data with the etching parameters a, b, and c as inputs and the etching performance quantitative values A, B, and C as outputs) is acquired using, for example, an experimental design method.
- step 904 an optimal parameter calculation model using a response curve is created.
- An optimal parameter calculation model to be generated by the response surface method is a multidimensional model with the items of the target etching performance quantitative value A, B, C as inputs and the etching parameters a, b, and c as outputs.
- a desired etching target value is set.
- an etching pattern is a contact hole
- roughness of a white band portion contour, roughness of a hole bottom pattern, a hole depth, an inclination angle of a hole wall, and the like are target values.
- the etching target value is inputted to the optimal parameter calculation model prepared in advance in step 301 to calculate initial etching parameters.
- FIG. 7 is a block diagram showing a structure of the scanning electron microscope (SEM) that observes an object formed by etching on a wafer (contact hole, etc.).
- SEM scanning electron microscope
- a primary electron beam 702 emitted from an electron gun 701 of an electro-optic system 700 is focused and irradiated on a wafer 710 placed on a stage 711 through a condensing lens 703 , a beam deflector 704 , an E ⁇ B deflector 705 , and an object lens 706 .
- a secondary electron is generated from the wafer 710 .
- the secondary electron generated from the wafer 710 is deflected by the E ⁇ B deflector 705 and detected by a secondary electron detector 707 .
- a two-dimensional electron beam image is obtained by two-dimensional scanning of the electron beam by the beam deflector 704 or repeated scanning in an X direction of the electron beam by the beam deflector and detection of electrons that are generated from the wafer 710 in synchronization with continuous movement in a Y direction of the wafer 710 by a stage 711 .
- a signal detected by the secondary electron detector 707 is converted into a digital signal by an A/D converter 708 and sent to an image processing unit 720 .
- the image processing unit 720 has an image memory for temporarily storing a digital image and a CPU that performs calculation for a line profile and a characteristic amount from an image on the image memory.
- the image processing unit 720 has a storage medium 721 for saving the characteristic amount calculated from a result of image processing as a database and a display 722 that displays the image and the processing result.
- a correspondence model of etching parameters which are adjusted to obtain a desired etching pattern, and a characteristic amount, which is desired from an electron image of an etching pattern that is formed when the etching parameters are changed, (hereinafter referred to as an optimal parameter calculation model) is derived by a preliminary experiment and saved in a storage 5 b shown in FIG. 1 .
- a scanning electron microscope that picks up a tilt image may be used in addition to the one that picks up a top-down view image.
- a system for inclining a table 711 on which the wafer 710 is mounted or a system for controlling a trajectory of a primary electron beam with an electro-optic system of the scanning electron microscope (SEM) to make the primary electron beam incident on a wafer surface from an inclined direction maybe adopted.
- a tilt angle an inclination angle of a primary electron beam with respect to a normal direction of the wafer surface
- a tilt angle is set between 0° to about 15° to obtain a tilt image.
- FIG. 13 shows an example of an SEM structure for obtaining a tilt image by inclining a table (tilt stage).
- the SEM structure shown in FIG. 13 is substantially the same as that shown in FIG. 7 .
- a primary electron beam 1302 emitted from an electron gun 1301 of an electro-optic system 1300 is focused and irradiated on a wafer 1301 placed on a stage 1311 through a condensing lens 1303 , a beam deflector 1304 , an E ⁇ B deflector 1305 , and an object lens 1306 .
- a secondary electron generated from the wafer 1310 is deflected by the E ⁇ B deflector 1305 , detected by a secondary electron detector 1307 , converted into a digital signal by an A/D converter 1308 , and sent to an image processing unit 1320 .
- the image processing unit 1320 has an image memory for temporarily storing a digital image and a CPU that performs calculation for a line profile and a characteristic amount from an image on the image memory.
- the image processing unit 1320 has a storage medium 1321 for saving the characteristic amount calculated from a result of image processing as a database and a display 1322 that displays the image and the processing result.
- the structure show in FIG. 13 is different from the structure shown in FIG. 7 in that the table 1311 has a tilt function and it is possible to set an inclination angle of a primary electron beam with respect to a normal direction of a surface of the wafer 1311 to obtain a tilt image.
- the image processing unit 1320 calculates a height of a pattern according to a principle of stereo graphic view from a tilt image and a top-down view image obtained by the SEM with such a structure, and information on a three-dimensional structure (a pattern height, a taper angle, etc.) is used as a characteristic amount of an etching pattern. Consequently, more detailed setting for an etching target is performed.
- an etching performance quantitative value is proposed.
- the etching performance quantitative value is obtained by picking up an image of an object generated by etching with an SEM and applying image processing to the picked-up image.
- characteristic amounts a line width 401 , line edge roughness 402 , a white band width 403 , etc.
- characteristic amounts (a hole diameter 410 , hole roundness 411 , a white band portion width 412 , roughness of a white portion contour line 413 , roughness of a contact hole bottom pattern 414 , etc.) are represented quantitatively by image processing as shown in FIG. 4B .
- FIG. 5 shows a method of deriving a workmanship quantitative value of a contact hole.
- step 306 It is judged using threshold processing or the like whether or not the performance quantitative value calculated in step 306 is within a fixed allowable range with respect to the etching target value set in step 302 . In addition, an amount of deviation of an optimal etching parameter from a target value is calculated.
- FIG. 10 a conceptual diagram showing how optimal etching parameters are calculated from an amount of deviation of an etching performance quantitative value from a target value.
- a three-dimensional model in which only etching parameter elements a and b relate to an etching performance quantitative value A, is assumed.
- the etching performance value A does not satisfy a target value
- the etching parameters are changed finely in a direction of the change and use them as next etching parameters.
- an optimal etching parameter determination method which uses an optimal parameter calculation model at the time when the etching performance quantitative values are A, B, and C in the case in which etching parameters are a, b, c, d, e, and f.
- a three-dimensional model in which only the etching parameters a and b, the etching parameters b and c, and the etching parameters c and a relate to the etching performance quantitative values (which is indicated as “etching performance” in the figure) A, B, and C, respectively, is assumed.
- an optimal parameter calculation model which is generated according to the response surface method, is a multidimensional model with the items of the target etching performance quantitative value A, B, and C as inputs and the etching parameters a, b, and c as outputs.
- etching parameters most suitable for realizing desired etching are derived on the basis of the optimal parameter calculation model.
- etching parameters are changed finely.
- etching parameters leading to an optimal etching performance value, which are calculated from the model may be used as the next etching parameters directly.
- An etching performance quantitative value after etching calculated in step 306 is displayed on a GUI shown in FIG. 8 .
- An inputted image 801 and a result of performance quantization area extraction 802 are displayed in an upper part of the screen and a result of judgment on quality of etching and performance quantitative values (hole diameter, white band portion thickness, white band portion contour roughness, hole bottom pattern roughness, etc.) are displayed in a lower part of the screen ( 803 ) such that a user can easily understand a state of etching performance.
- a result of the quality judgment for etching calculated in step 307 indicates defectiveness
- a result of judging a cause of the defectiveness is also displayed ( 804 ).
- This embodiment is a system that automatically derives etching parameters most suitable for realizing target etching as in the above-mentioned method.
- This embodiment is an example concerning optimization for etching parameters in an etching process at the time of mass production in semiconductor manufacturing.
- FIG. 6 shows a constitution of this embodiment.
- the optimal parameter calculation model is used again after the correction to calculate an optimal recipe from the target value.
- values of etching parameters calculated from the corrected model are outside a range of values that can be set by the etching apparatus.
- an alarm is notified for etching treatment for a second wafer to prevent the etching treatment from being performed. Consequently, when abnormality has occurred in the apparatus, a large number of defects can be prevented from being caused.
- this alarm can also be used for judgment on execution of maintenance processing called total cleaning.
- optimal etching parameters are set in an etching process at the time of mass production.
- step 601 an etching target value for an etching pattern to be formed by etching is set.
- step 602 initial etching parameters are set.
- step 603 etching is performed on the basis of the etching parameters set in step 602 .
- step 604 an image of an etching pattern on a wafer formed by the etching is picked up by a scanning electron microscope (SEM) or the like.
- step 605 a performance value of the etching is calculated by image processing with respect to the image obtained in step 604 .
- step 606 it is judged whether the obtained etching performance value satisfies the etching target value set in step 601 .
- the etching performance value satisfies the etching target value, wafers are subjected to etching treatment one after another without changing the etching parameters at that point.
- step 606 If it is judged in step 606 that the etching performance value does not satisfy the etching target value, in step 608 , an etching parameter corrected value for bringing an etching result close to the target etching value is calculated, and a result of the calculation is fed back to step 602 for setting optimal etching parameters to set optimal etching parameters. Then, etching is performed again with an etching recipe based on the etching parameters set anew.
- the present invention makes it possible to calculate optimal etching parameters for obtaining desired etching performance in an etching process in semiconductor manufacturing.
- the present invention makes it possible to control influence of disturbance due to continuous operation of an apparatus to continue etching with optimal parameters at the time of mass production in an etching process.
Abstract
Description
- This application relates to and claims priority from Japanese Patent Application No. 2003-198844, filed on Jul. 18, 2003, the entire disclosure of which is incorporated herein by reference.
- 1. Field of the Invention
- The present invention relates to a method of setting optimal etching parameters in a semiconductor manufacturing process and a system therefor. More specifically, the present invention relates to a system that picks up an image of a pattern formed on a wafer, represents workmanship of the pattern quantitatively, performs etching parameter correction for reducing an amount of deviation between a quantitative value of the workmanship and a target etching pattern, and realizes setting for optimal etching parameters, and a performance evaluation system that evaluates performance of etching.
- 2. Description of the Related Art
- A conventional method of setting etching parameters (a gas flowrate, a pressure, a voltage, electric power, temperature, time, etc.) for an etching process in semiconductor manufacturing will be explained with reference to
FIG. 2 . In the etching process, in order to obtain desired etching performance, it is necessary to set plural etching parameters to optimal values. - Instep 201, in order to perform desired etching, a person determines initial values of etching parameters, which are suitable for a quality of material of an etching object and an etching shape, with a help of experiences in the past and intuition on the basis of characteristics, which have been obtained through experiments, concerning the quality of material of the etching object and characteristics of an etching apparatus being used.
- In
step 202, the person performs etching with the etching parameters determined instep 201. Instep 203, the person observes a pattern on a wafer, which is formed by the etching, with a scanning electron microscope (SEM) or the like to measure the etching pattern. Instep 204, the person judges manually whether desired etching performance is obtained on the basis of a measurement value obtained instep 203. If it can be judged that a result of the etching is satisfactory, the person determines etching parameters. - If it is judged that the result of the etching is unsatisfactory, in
step 205, the person performs correction for the etching parameters, which brings etching performance close to the desired etching performance, on the basis of experiences in the past. Then, the person returns tostep 202 and performs etching again with etching parameters set anew. - According the method described above, the person determines etching parameters most suitable for obtaining the desired etching performance.
- In the above-mentioned conventional technique, the person determines initial values and corrected values of etching parameters according to experiences and intuition to derive optimal etching parameters. However, such manual setting for etching parameters is inefficient because the manual setting takes time until optimal setting for etching parameters is obtained. In addition, it is possible that set values contain individual differences.
- Thus, the present invention has been devised in view of these problems, and it is an object of the present invention to provide a method of setting optimal etching parameters for performing desired etching and a system therefor.
- The present invention provides a method of setting parameters for etching, which includes: acquiring an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; processing the acquired electron beam image of the pattern formed on the surface of the wafer to judge workmanship of the pattern; presenting a result of judging the workmanship to a user; calculating corrected values of etching parameters for the etching apparatus on the basis of the result of judging the workmanship; and sending the calculated corrected value to the etching apparatus, and a system for the method.
- In addition, the present invention provides a method of setting parameters for etching, which includes: acquiring an electron beam image of a pattern formed on a surface of a wafer treated by an etching apparatus; processing the acquired electron beam image of the pattern formed on the surface of the wafer to extract a characteristic amount of the pattern; comparing the extracted characteristic amount of the pattern with data set in advance to judge workmanship of the pattern; presenting a result of judging the workmanship to a user; and calculating corrected values of etching parameters for the etching apparatus on the basis of the result of judging the workmanship, and a system for the method.
- These and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings.
- In the accompanying drawings:
-
FIG. 1 is a diagram showing a system for setting optimal etching parameters according to the present invention; -
FIG. 2 is a diagram showing a conventional method; -
FIG. 3 is a conceptual diagram showing the system for setting optimal etching parameters; -
FIGS. 4A and 4B are diagrams showing examples of characteristics of etching performance; -
FIG. 5 is a flow diagram of processing for deriving an etching performance quantitative value; -
FIG. 6 is a conceptual diagram showing a system for setting optimal etching parameters in a mass production process; -
FIG. 7 is a diagram showing a structure of a scanning electron microscope (SEM); -
FIG. 8 is a diagram showing an example of GUI display of an etching performance quantitative value; -
FIG. 9 is a flow diagram of processing for creating an optimal parameter calculation model; -
FIG. 10 is a conceptual diagram showing a method of changing parameters; -
FIG. 11 is a flow diagram of processing for setting optimal etching parameters; -
FIG. 12 is a flow diagram of correction for the optimal parameter calculation model in a mass production process; and -
FIG. 13 is a diagram showing a structure of a scanning electron microscope (SEM) that is capable of acquiring a tilt image. - Embodiments of the present invention will be hereinafter explained with reference to the accompanying drawings.
- Outline
-
FIG. 1 shows a system configuration for automating parameter setting at the time of an etching process in semiconductor manufacturing in accordance with an embodiment of the present invention. This system includes anetching apparatus 1, a scanning electron microscope (SEM) 2 that picks up images of an etching pattern, and acomputer 3 including aprocessing unit 4, which performs image processing and optimal etching parameter derivation processing, and astorage 5, which saves etching pattern images, etching parameters, and the like. The respective components are connected by a bus 6. -
FIG. 3 shows a flow of processing of this system. First, instep 301, a modeled relation between various image characteristic amounts, which are derived from electron beam images of etching patterns that are formed when etching is performed by changing etching parameters (a gas flow rate, a pressure, wafer temperature, a coil magnetic field, etc.) in various ways, and the etching parameters are prepared in a preliminary experiment (hereinafter referred to as an optimal parameter calculation model). Instep 302, an etching target value for an etching pattern to be formed by etching is set. Instep 303, initial etching parameters are set using the optimal parameter calculation model prepared in advance. Instep 304, etching is performed on the basis of the etching parameters set instep 303. Instep 305, an image of an etching pattern on a wafer formed by the etching is picked up by a scanning electron microscope (SEM) or the like. Instep 306, a performance value of the etching is calculated by image processing with respect to the image obtained instep 305. Instep 307, it is judged whether the obtained etching performance value satisfies the etching target value. If the etching performance value satisfies the etching target value, an etching recipe at that point is set as optimal etching parameters for the etching target value. If the etching performance value does not satisfy the etching target value, instep 308, an etching parameter corrected value for bringing an etching result close to the target etching value is calculated on the basis of the optimal parameter calculation model. Instep 309, optimal etching parameters are set on the basis of the calculated corrected value. Then, etching is performed again with an etching recipe set anew (the processing is returned to step 304). - Details of the respective steps will be hereinafter explained.
- (1) Derivation of an Optimal Parameter Calculation Model (
Step 301 inFIG. 3 ). - A method of deriving an optimal parameter calculation model will be explained. In this embodiment, a response surface model, which is generally used for statistical processing, is used as a modeling method for an optimal parameter calculation model.
FIG. 9 is a diagram showing processing to establishing an optimal parameter calculation model. First, it is assumed that items of a target etching performance quantitative value are A, B, and C, and items of etching parameters to be set in an etching apparatus are a, b, c, d, e, and f. A, B, and C are, for example, line edge roughness, a line width, a contact hole diameter, a hole roundness, and a characteristic amount of a contact hole bottom pattern, and a, b, c, d, e, and f are, for example, a gas flow rate, a pressure, a voltage, electric power, temperature, and time. - First, in
step 901, an evaluation experiment using, for example, a Taguchi method is performed to find parameters, which affect in-plane evenness in an etching process, among the etching parameters. Instep 902, the etching parameters affecting in-plane evenness are excluded from controllable parameters (e.g., d, e, and f). These parameters are always fixed as fixed etching parameters, whereby evenness on a wafer is prevented from being ruined. Instep 903, experiment data necessary for the derivation of an optimal parameter calculation model (experiment data with the etching parameters a, b, and c as inputs and the etching performance quantitative values A, B, and C as outputs) is acquired using, for example, an experimental design method. Instep 904, an optimal parameter calculation model using a response curve is created. An optimal parameter calculation model to be generated by the response surface method is a multidimensional model with the items of the target etching performance quantitative value A, B, C as inputs and the etching parameters a, b, and c as outputs. - (2) Setting for an Etching Target Value (
Step 302 inFIG. 3 ) - A desired etching target value is set. For example, in the case in which an etching pattern is a contact hole, a hole diameter, hole roundness, a white band portion width in an image photographed by a scanning electron microscope, roughness of a white band portion contour, roughness of a hole bottom pattern, a hole depth, an inclination angle of a hole wall, and the like are target values.
- (3) Etching Parameter Setting Using the Optimal Parameter Calculation Model
- The etching target value is inputted to the optimal parameter calculation model prepared in advance in
step 301 to calculate initial etching parameters. - (4) Acquisition of an SEM Image (
step 305 inFIG. 3 ) - An image of an etching pattern is picked up by a scanning electron microscope (SEM).
FIG. 7 is a block diagram showing a structure of the scanning electron microscope (SEM) that observes an object formed by etching on a wafer (contact hole, etc.). InFIG. 7 , aprimary electron beam 702 emitted from anelectron gun 701 of an electro-optic system 700 is focused and irradiated on awafer 710 placed on astage 711 through a condensinglens 703, abeam deflector 704, an E×B deflector 705, and anobject lens 706. When the electron beam is irradiated, a secondary electron is generated from thewafer 710. - The secondary electron generated from the
wafer 710 is deflected by the E×B deflector 705 and detected by asecondary electron detector 707. A two-dimensional electron beam image is obtained by two-dimensional scanning of the electron beam by thebeam deflector 704 or repeated scanning in an X direction of the electron beam by the beam deflector and detection of electrons that are generated from thewafer 710 in synchronization with continuous movement in a Y direction of thewafer 710 by astage 711. - A signal detected by the
secondary electron detector 707 is converted into a digital signal by an A/D converter 708 and sent to animage processing unit 720. Theimage processing unit 720 has an image memory for temporarily storing a digital image and a CPU that performs calculation for a line profile and a characteristic amount from an image on the image memory. In addition, theimage processing unit 720 has astorage medium 721 for saving the characteristic amount calculated from a result of image processing as a database and adisplay 722 that displays the image and the processing result. - In this embodiment, prior to carrying in a product wafer, a correspondence model of etching parameters, which are adjusted to obtain a desired etching pattern, and a characteristic amount, which is desired from an electron image of an etching pattern that is formed when the etching parameters are changed, (hereinafter referred to as an optimal parameter calculation model) is derived by a preliminary experiment and saved in a storage 5 b shown in
FIG. 1 . - As the scanning electron microscope to be used, a scanning electron microscope that picks up a tilt image may be used in addition to the one that picks up a top-down view image. As means for picking up a tilt image, a system for inclining a table 711 on which the
wafer 710 is mounted or a system for controlling a trajectory of a primary electron beam with an electro-optic system of the scanning electron microscope (SEM) to make the primary electron beam incident on a wafer surface from an inclined direction maybe adopted. In both the systems, a tilt angle (an inclination angle of a primary electron beam with respect to a normal direction of the wafer surface) is set between 0° to about 15° to obtain a tilt image. -
FIG. 13 shows an example of an SEM structure for obtaining a tilt image by inclining a table (tilt stage). The SEM structure shown inFIG. 13 is substantially the same as that shown inFIG. 7 . Aprimary electron beam 1302 emitted from anelectron gun 1301 of an electro-optic system 1300 is focused and irradiated on awafer 1301 placed on astage 1311 through a condensinglens 1303, abeam deflector 1304, an E×B deflector 1305, and anobject lens 1306. A secondary electron generated from thewafer 1310 is deflected by the E×B deflector 1305, detected by asecondary electron detector 1307, converted into a digital signal by an A/D converter 1308, and sent to animage processing unit 1320. Theimage processing unit 1320 has an image memory for temporarily storing a digital image and a CPU that performs calculation for a line profile and a characteristic amount from an image on the image memory. In addition, theimage processing unit 1320 has astorage medium 1321 for saving the characteristic amount calculated from a result of image processing as a database and adisplay 1322 that displays the image and the processing result. - Here, the structure show in
FIG. 13 is different from the structure shown inFIG. 7 in that the table 1311 has a tilt function and it is possible to set an inclination angle of a primary electron beam with respect to a normal direction of a surface of thewafer 1311 to obtain a tilt image. Theimage processing unit 1320 calculates a height of a pattern according to a principle of stereo graphic view from a tilt image and a top-down view image obtained by the SEM with such a structure, and information on a three-dimensional structure (a pattern height, a taper angle, etc.) is used as a characteristic amount of an etching pattern. Consequently, more detailed setting for an etching target is performed. - (5) Performance Quantization (
Step 306 inFIG. 3 ) - As an example of a characteristic amount derived from an electron beam image of an etching pattern (a line patter, a hole pattern, etc.), an etching performance quantitative value is proposed. The etching performance quantitative value is obtained by picking up an image of an object generated by etching with an SEM and applying image processing to the picked-up image. For example, in the case in which an object of formation on a wafer to be observed is a line pattern, characteristic amounts (a
line width 401,line edge roughness 402, awhite band width 403, etc.) are represented quantitatively by image processing as shown inFIG. 4A . - In addition, in the case in which an object of formation on a wafer is a hole pattern, characteristic amounts (a
hole diameter 410, hole roundness 411, a whiteband portion width 412, roughness of a whiteportion contour line 413, roughness of a contacthole bottom pattern 414, etc.) are represented quantitatively by image processing as shown inFIG. 4B .FIG. 5 shows a method of deriving a workmanship quantitative value of a contact hole. - (6) Judgment (
Step 307 inFIG. 3 ) - It is judged using threshold processing or the like whether or not the performance quantitative value calculated in
step 306 is within a fixed allowable range with respect to the etching target value set instep 302. In addition, an amount of deviation of an optimal etching parameter from a target value is calculated. - (7) Etching Parameter Correction Using a Minimum Parameter Calculation Model
-
FIG. 10 a conceptual diagram showing how optimal etching parameters are calculated from an amount of deviation of an etching performance quantitative value from a target value. In the figure, in order to facilitate explanation, a three-dimensional model, in which only etching parameter elements a and b relate to an etching performance quantitative value A, is assumed. In the case in which the etching performance value A does not satisfy a target value, it is assumed from a shape of a model surface how the etching parameters (the parameters a and b) should be change from etching parameter positions on the model at that point to bring a result of etching close to a target etching performance value. The etching parameters are changed finely in a direction of the change and use them as next etching parameters. - In
FIG. 11 , an optimal etching parameter determination method is shown which uses an optimal parameter calculation model at the time when the etching performance quantitative values are A, B, and C in the case in which etching parameters are a, b, c, d, e, and f. In this figure, a three-dimensional model, in which only the etching parameters a and b, the etching parameters b and c, and the etching parameters c and a relate to the etching performance quantitative values (which is indicated as “etching performance” in the figure) A, B, and C, respectively, is assumed. Actually, as described before, an optimal parameter calculation model, which is generated according to the response surface method, is a multidimensional model with the items of the target etching performance quantitative value A, B, and C as inputs and the etching parameters a, b, and c as outputs. - As described above, etching parameters most suitable for realizing desired etching are derived on the basis of the optimal parameter calculation model. In the above-mentioned method, etching parameters are changed finely. However, etching parameters leading to an optimal etching performance value, which are calculated from the model, may be used as the next etching parameters directly.
- (8) GUI (
Step 306 andStep 307 inFIG. 3 ) - An etching performance quantitative value after etching calculated in
step 306 is displayed on a GUI shown inFIG. 8 . An inputtedimage 801 and a result of performancequantization area extraction 802 are displayed in an upper part of the screen and a result of judgment on quality of etching and performance quantitative values (hole diameter, white band portion thickness, white band portion contour roughness, hole bottom pattern roughness, etc.) are displayed in a lower part of the screen (803) such that a user can easily understand a state of etching performance. - In addition, if a result of the quality judgment for etching calculated in
step 307 indicates defectiveness, a result of judging a cause of the defectiveness (etching stop, occurrence of deposition, etc.) is also displayed (804). - This embodiment is a system that automatically derives etching parameters most suitable for realizing target etching as in the above-mentioned method.
- System for Calculating Optimal Etching Parameters at the Time of Mass Production
- This embodiment is an example concerning optimization for etching parameters in an etching process at the time of mass production in semiconductor manufacturing.
FIG. 6 shows a constitution of this embodiment. When an etching apparatus is continuously operated at the time of mass production in semiconductor manufacturing, with the method of deriving etching parameters described above (first embodiment), desired etching cannot be calculated in some cases due to disturbance such as dirt in the apparatus. Such a situation may be caused because effective values of etching parameters deviate from set values thereof due to dirt in the apparatus. This is equivalent to deviation of axes of etching parameters in an optimal etching parameter calculation model. Thus, in order to control between-lot variation, within-lot variation, and dispersion variation based on variation with time and to carry out accurate device processing, in the case in which a result of measurement of the etching parameters deviates from a target value, axes of etching parameters at the time of creation of an initial calculation model are corrected. - The optimal parameter calculation model is used again after the correction to calculate an optimal recipe from the target value. However, in the case in which values of etching parameters calculated from the corrected model are outside a range of values that can be set by the etching apparatus, an alarm is notified for etching treatment for a second wafer to prevent the etching treatment from being performed. Consequently, when abnormality has occurred in the apparatus, a large number of defects can be prevented from being caused. In addition, this alarm can also be used for judgment on execution of maintenance processing called total cleaning. According to the above-mentioned method, optimal etching parameters are set in an etching process at the time of mass production.
- A processing flow shown in
FIG. 6 will be explained. First, instep 601, an etching target value for an etching pattern to be formed by etching is set. Instep 602, initial etching parameters are set. Instep 603, etching is performed on the basis of the etching parameters set instep 602. Instep 604, an image of an etching pattern on a wafer formed by the etching is picked up by a scanning electron microscope (SEM) or the like. Instep 605, a performance value of the etching is calculated by image processing with respect to the image obtained instep 604. Instep 606, it is judged whether the obtained etching performance value satisfies the etching target value set instep 601. Here, if the etching performance value satisfies the etching target value, wafers are subjected to etching treatment one after another without changing the etching parameters at that point. - If it is judged in
step 606 that the etching performance value does not satisfy the etching target value, instep 608, an etching parameter corrected value for bringing an etching result close to the target etching value is calculated, and a result of the calculation is fed back to step 602 for setting optimal etching parameters to set optimal etching parameters. Then, etching is performed again with an etching recipe based on the etching parameters set anew. - The present invention makes it possible to calculate optimal etching parameters for obtaining desired etching performance in an etching process in semiconductor manufacturing. In addition, the present invention makes it possible to control influence of disturbance due to continuous operation of an apparatus to continue etching with optimal parameters at the time of mass production in an etching process.
- The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefor to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (22)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003-198844 | 2003-07-18 | ||
JP2003198844A JP2005038976A (en) | 2003-07-18 | 2003-07-18 | Optimal etching parameter automatic setting system and etching result evaluation system |
Publications (1)
Publication Number | Publication Date |
---|---|
US20050016682A1 true US20050016682A1 (en) | 2005-01-27 |
Family
ID=34074392
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/893,275 Abandoned US20050016682A1 (en) | 2003-07-18 | 2004-07-19 | Method of setting etching parameters and system therefor |
Country Status (2)
Country | Link |
---|---|
US (1) | US20050016682A1 (en) |
JP (1) | JP2005038976A (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110083808A1 (en) * | 2009-10-09 | 2011-04-14 | Hitachi High-Technologies Corporation | Plasma processing apparatus |
US20110224945A1 (en) * | 2010-03-11 | 2011-09-15 | Samsung Electronics Co., Ltd. | Method of performing etch proximity correction, method of forming photomask layout using the method, computer-readable recording medium storing programmed instructions for executing the method, and mask imaging system |
TWI561942B (en) * | 2014-11-27 | 2016-12-11 | Hitachi High Tech Corp | |
US10720307B2 (en) | 2016-09-14 | 2020-07-21 | Hitachi High-Technologies Corporation | Electron microscope device and inclined hole measurement method using same |
CN112713113A (en) * | 2021-01-14 | 2021-04-27 | 长鑫存储技术有限公司 | Inclination angle prediction method and device, equipment monitoring method, medium and equipment |
US11300887B2 (en) | 2016-12-02 | 2022-04-12 | Asml Netherlands B.V. | Method to change an etch parameter |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009290150A (en) * | 2008-06-02 | 2009-12-10 | Renesas Technology Corp | System and method for manufacturing semiconductor device |
JP5386502B2 (en) * | 2008-11-05 | 2014-01-15 | 株式会社日立ハイテクノロジーズ | Pattern dimension measuring method and scanning electron microscope using the same |
JP5596832B2 (en) * | 2013-07-29 | 2014-09-24 | 株式会社日立ハイテクノロジーズ | Run-to-run control method of plasma processing method |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5661669A (en) * | 1993-12-17 | 1997-08-26 | Texas Instruments Incorporated | Method for controlling semiconductor wafer processing |
US6388253B1 (en) * | 1999-06-29 | 2002-05-14 | Applied Materials, Inc. | Integrated critical dimension control for semiconductor device manufacturing |
US20020141647A1 (en) * | 2001-03-27 | 2002-10-03 | Kabushiki Kaisha Toshiba | Pattern evaluation method, pattern evaluation system and computer-readable recorded medium |
US6505090B1 (en) * | 1998-12-15 | 2003-01-07 | Kabushiki Kaisha Toshiba | Semiconductor device manufacturing method, manufacturing system, support system and recording medium storing program of and data for the manufacture method |
US20030049376A1 (en) * | 2001-06-19 | 2003-03-13 | Applied Materials, Inc. | Feedback control of sub-atmospheric chemical vapor deposition processes |
US20030113945A1 (en) * | 2001-06-29 | 2003-06-19 | Akira Kagoshima | Disturbance-free, recipe-controlled plasma processing system and method |
US20030209667A1 (en) * | 2002-05-13 | 2003-11-13 | Applied Materials Israel Ltd | Charged particle beam apparatus and method for inspecting samples |
US6724947B1 (en) * | 2000-07-14 | 2004-04-20 | International Business Machines Corporation | Method and system for measuring characteristics of curved features |
-
2003
- 2003-07-18 JP JP2003198844A patent/JP2005038976A/en active Pending
-
2004
- 2004-07-19 US US10/893,275 patent/US20050016682A1/en not_active Abandoned
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5661669A (en) * | 1993-12-17 | 1997-08-26 | Texas Instruments Incorporated | Method for controlling semiconductor wafer processing |
US6505090B1 (en) * | 1998-12-15 | 2003-01-07 | Kabushiki Kaisha Toshiba | Semiconductor device manufacturing method, manufacturing system, support system and recording medium storing program of and data for the manufacture method |
US6388253B1 (en) * | 1999-06-29 | 2002-05-14 | Applied Materials, Inc. | Integrated critical dimension control for semiconductor device manufacturing |
US6724947B1 (en) * | 2000-07-14 | 2004-04-20 | International Business Machines Corporation | Method and system for measuring characteristics of curved features |
US20020141647A1 (en) * | 2001-03-27 | 2002-10-03 | Kabushiki Kaisha Toshiba | Pattern evaluation method, pattern evaluation system and computer-readable recorded medium |
US20030049376A1 (en) * | 2001-06-19 | 2003-03-13 | Applied Materials, Inc. | Feedback control of sub-atmospheric chemical vapor deposition processes |
US20030113945A1 (en) * | 2001-06-29 | 2003-06-19 | Akira Kagoshima | Disturbance-free, recipe-controlled plasma processing system and method |
US20030209667A1 (en) * | 2002-05-13 | 2003-11-13 | Applied Materials Israel Ltd | Charged particle beam apparatus and method for inspecting samples |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20110083808A1 (en) * | 2009-10-09 | 2011-04-14 | Hitachi High-Technologies Corporation | Plasma processing apparatus |
US8992721B2 (en) | 2009-10-09 | 2015-03-31 | Hitachi High-Technologies Corporation | Plasma processing apparatus |
US10262840B2 (en) | 2009-10-09 | 2019-04-16 | Hitachi High-Technologies Corporation | Plasma processing apparatus |
US20110224945A1 (en) * | 2010-03-11 | 2011-09-15 | Samsung Electronics Co., Ltd. | Method of performing etch proximity correction, method of forming photomask layout using the method, computer-readable recording medium storing programmed instructions for executing the method, and mask imaging system |
TWI561942B (en) * | 2014-11-27 | 2016-12-11 | Hitachi High Tech Corp | |
US10720307B2 (en) | 2016-09-14 | 2020-07-21 | Hitachi High-Technologies Corporation | Electron microscope device and inclined hole measurement method using same |
US11300887B2 (en) | 2016-12-02 | 2022-04-12 | Asml Netherlands B.V. | Method to change an etch parameter |
CN112713113A (en) * | 2021-01-14 | 2021-04-27 | 长鑫存储技术有限公司 | Inclination angle prediction method and device, equipment monitoring method, medium and equipment |
Also Published As
Publication number | Publication date |
---|---|
JP2005038976A (en) | 2005-02-10 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6113842B2 (en) | End point determination of focused ion beam processing | |
US9390490B2 (en) | Method and device for testing defect using SEM | |
JP5973466B2 (en) | Preparation of TEM sample | |
US7816062B2 (en) | Method and apparatus for semiconductor device production process monitoring and method and apparatus for estimating cross sectional shape of a pattern | |
US8750597B2 (en) | Robust inspection alignment of semiconductor inspection tools using design information | |
US7095884B2 (en) | Method and apparatus for circuit pattern inspection | |
US7889908B2 (en) | Method and apparatus for measuring shape of a specimen | |
US20070018099A1 (en) | Method of measuring three-dimensional surface roughness of a structure | |
US6984589B2 (en) | Method for determining etching process conditions and controlling etching process | |
JP6112929B2 (en) | Focused ion beam apparatus, sample processing method using the same, and sample processing computer program using focused ion beam | |
US20120070089A1 (en) | Method of manufacturing a template matching template, as well as a device for manufacturing a template | |
US10115561B2 (en) | Method of analyzing surface modification of a specimen in a charged-particle microscope | |
JP6731370B2 (en) | Image processing system and computer program for performing image processing | |
US20050016682A1 (en) | Method of setting etching parameters and system therefor | |
JP4240066B2 (en) | Etching process monitoring method and etching process control method | |
JPWO2010106837A1 (en) | Pattern inspection apparatus and inspection method therefor | |
JP5286337B2 (en) | Semiconductor manufacturing apparatus management apparatus and computer program | |
WO2020250373A1 (en) | Image processing program, image processing device and image processing method | |
US20050061974A1 (en) | Method of analyzing material structure using CBED | |
JPH10274626A (en) | Image-processing apparatus | |
JP5439106B2 (en) | Pattern shape evaluation apparatus and method using scanning charged particle microscope | |
US20110194778A1 (en) | Pattern-searching condition determining method, and pattern-searching condition setting device | |
JP4002037B2 (en) | Reference image creation method, pattern recognition method, and recording medium | |
JPH09223726A (en) | Charged particle beam type tomographic analyzer system, method thereof and charged particle beam processor | |
TW202247224A (en) | Depth measurement device, depth measurement system, and depth index value calculation method |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: HITACHI HIGH-TECHNOLOGIES CORPORATION, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:NAGATOMA, WATARU;NAKAGAKI, RYO;TANAKA, MAKI;AND OTHERS;REEL/FRAME:015845/0759 Effective date: 20040709 |
|
AS | Assignment |
Owner name: HITACHI HIGH-TECHNOLOGIES CORPORATION, JAPAN Free format text: CORRECTED ASSIGNMENT 1ST INVENTOR'S NAME MISSPELLED AND ALSO, EXECUTION DATES ARE INCORRECT FOR 2ND, 3RD, AND 5TH INVENTORS ON THE PART OF THE USPTO. PREVIOUSLY RECORDED ON REEL/FRAME 015845/0759.;ASSIGNORS:NAGATOMO, WATARU;NAKAGAKI, RYO;TANAKA, MAKI;AND OTHERS;REEL/FRAME:017026/0552;SIGNING DATES FROM 20040709 TO 20040727 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |