CN103515181A

CN103515181A - Methods and apparatus for controlling plasma in a plasma processing system

Info

Publication number: CN103515181A
Application number: CN201310253580.0A
Authority: CN
Inventors: 约翰·C·小瓦尔考; 布拉德福德·J·林达克
Original assignee: Lam Research Corp
Current assignee: Lam Research Corp
Priority date: 2012-06-22
Filing date: 2013-06-24
Publication date: 2014-01-15
Anticipated expiration: 2033-06-24
Also published as: KR20140000172A; TW201415519A; CN105914123B; CN105914123A; TWI592978B; CN103515181B; KR102133057B1

Abstract

The invention relates to methods and apparatus for controlling plasma in a plasma processing system, and specifically discloses methods and apparatus for processing a substrate in a multi-frequency plasma processing chamber. A base RF signal applies a pulse between a high power level and a low power level. When the base RF signal applies the pulse, each of non-base RF generators proactively switches between a first predefined power level and a second predefined power level in response to a control signal. Alternatively or additionally, when the base RF signal applies the pulse, each of the non-base RF generators proactively switches between a first predefined RF frequency and a second predefined RF frequency in response to a control signal. The invention discloses a technique used for determining the first and the second predefined power levels and /or the first and the second predefined RF frequencies for a non-base RF signal before production time.

Description

For control the method and apparatus of plasma at plasma process system

Related application

The name of submitting in the application's claim and on February 22nd, 2012 is called " FREQUENCY ENHANCED IMPEDANCE DEPENDENT POWER CONTROL FOR MULTI-FREQUENCY RF PULSING ", attorney is P2301P/LMRX-P222P1, application number is 61/602, 040 commonly assigned patent application is relevant, and be called " METHODS AND APPARATUS FOR SYNCHRONIZING RF PULSES IN A PLASMA PROCESSING SYSTEM " with the name that on February 22nd, 2012 submits to, attorney is P2296P/LMRX-P221P1, application number is 61/602, 401 commonly assigned patent application is relevant, all above-mentioned applying for reference to being incorporated to herein.

Technical field

The application relates to plasma process system, especially relates to for control the method and apparatus of plasma at plasma process system.

Background technology

Plasma treatment is for example used to process substrate (for example, wafer or dull and stereotyped or other substrate), for a long time to produce electronic device (, integrated circuit or flat-panel monitor).In plasma treatment, substrate is placed in plasma processing chamber, and plasma processing chamber adopts one or more electrode to come excitaton source gas (it can be etchant source gas or sedimentary origin gas) to be formed for processing the plasma of substrate.Electrode can be by RF signal excitation, and this RF signal is for example provided by RF generator.

In some plasma process systems, a plurality of RF signals (some of them can have identical or different RF frequency) can be provided for substrate supporting electrode (herein also referred to as bottom electrode or chuck) to generate plasma, and top electrode is grounded simultaneously.In capacitance coupling plasma treatment system, for example, one or more RF signal can be provided for bottom electrode, and top electrode is grounded.

In some applications, can apply a plurality of RF signal pulses.For any given RF signal, RF pulse apply be included in can different from RF frequency (and being conventionally slower than RF frequency) pulse frequency this RF signal is opened or closed to (or between high power levels and low-power level alternately, because pulse applies not always required power, be closed).Generally speaking, RF pulse in the past applies and is performed to improve some result (such as improving uniformity or reducing the relevant infringement of etching).

It can be nonsynchronous or synchronous that the pulse of each RF signal applies.With regard to lock-out pulse applies, for example, if two signal RF1 and RF2 are synchronous, there is the active pulse for the signal RF1 of the active pulse of each signal RF2.The pulse of two RF signals can be homophase, or the rising edge of a RF pulse can lag behind the rising edge of another RF pulse, or the trailing edge of a RF pulse can lag behind the trailing edge of another RF pulse, or RF pulse can be out-phase.

If the pulse of each RF signal applies, be not well controlled, have following risk: at one or more RF signal, in the transition process of (vice versa), can cause the RF power of plasma perturbation unstable from low to high.This is that the condition of plasma in process chamber has changed because in such transition process of one or more RF signal.This change can be attempted matching network and/or other RF generator that the condition of plasma that detects of compensation changes by meeting and detect.The reactive person's character of this compensation (reactive nature) mean condition of plasma change to detect and successfully between compensation during, there is the RF power perturbation that causes plasma unstable.

Fig. 1 shows an example of this RF power perturbation, and it can cause the plasma unstable in the transition process of one of pulsed RF signal.In the example of Fig. 1,2MHz RF signal produces pulse with 50% duty ratio with 100Hz between 2500W and 0W.For purposes of illustration, suppose that 60MHz RF signal moves under continuous wave (CW) pattern, does not produce pulse.Along with 2MHz RF signal is converted to high state 104 from low state 102, in response to provided power, change, indoor condition of plasma changes.When this condition of plasma change being detected, 60MHz RF signal is depicted as the condition of plasma change that compensation (by the compensating circuit in 60MHz RF power supply or matching network) detects.

Yet this is reactive response and depends on and first detect the caused condition of plasma of 2MHz pulsed RF signal (as previously mentioned, its pulse frequency with 100Hz applies pulse) transformation from low to high and change.Postpone and response subsequently causes by the RF power level perturbation shown in reference number 106, reference number 106 shows the of short duration decline in the power level of 60MHz RF signal after 2MHz from low to high changes.After the 2MHz RF transformation from high (110) to low (112), another example of the RF power level perturbation in the 60MHz RF signal coming because of the delayed response of 60MHz RF signal is illustrated by reference number 108.Other RF power perturbation is illustrated by for

example reference number

114 and 116 in Fig. 1.As shown in Figure 1, these RF power perturbations can and can have different intensity in positive direction or in negative direction.Such perturbation causes unsettled and/or restive plasma event, affects result and/or yield of devices.

In addition,, in the manufacture of high density, high performance device, modern plasma treatment has been forced strict result requirement.With traditional constant waveform RF signal or with traditional RF pulse applying method, can not arrive some process window or these process window are very narrow.

The manipulation that the pulse of each RF signal applies and further control to improve plasma stability and/or to provide extra technology controlling and process button among a plurality of objects of embodiments of the present invention.

Summary of the invention

In one embodiment, the present invention relates to a kind of for process the method for substrate at the plasma processing chamber with at least one electrode.Described plasma processing chamber has and is coupled a plurality of RF power supplys that a plurality of RF signals are provided for described electrode.The method comprises makes base stage RF pulse signal between high power levels and low-power level, apply pulse in the first pulse frequency, described base stage RF pulse signal represents a RF signal of the minimum pulse frequency in the pulse frequency in described a plurality of RF signal with described a plurality of RF signals, and described the first pulse frequency is different from the RF frequency of described base stage RF pulse signal.

The method also comprises the subset that control signal is at least sent to described a plurality of RF power supplys, wherein when processing described substrate, described control signal is not to need taking the photograph and produce owing to applying the change of one or more chamber parameter that pulse comes described in described base pulse signal and carry out before the mode of sensing.

The method comprises in response to described control signal, in the first predefine RF power supply certain power level be different between the second predefine RF power supply certain power level of described the first predefine RF power supply certain power level, make each in the described subset of a plurality of described RF power supplys apply pulse.

Below in the specific embodiment of the present invention part, and by reference to the accompanying drawings, can be described in more detail these and other feature of the present invention.

Accompanying drawing explanation

In the accompanying drawings, in the mode of embodiment but not the present invention will be described in the mode of restriction, and wherein similarly reference number refer to similar element, wherein:

Fig. 1 shows the example of such RF power perturbation, and it can cause plasma unstable in the transition process of one of pulsed RF signal.

Fig. 2 shows having plasma processing chamber and being arranged to the capacitance coupling plasma treatment system of the simplification that power level that each RF signal pulse applies state controls according to the embodiment of the present invention.

The power output with respect to the time that Fig. 3 shows two RF signals with before explanation is between each RF signal, take the photograph the figure of the effect that applies of (proactively) lock-out pulse.

Fig. 4 shows situation according to an embodiment of the present invention, and wherein 60MHz RF signal has the power level that its pulse that adapts to 2MHz RF signal applies state.

Fig. 5 shows the situation according to another embodiment of the present invention, and wherein 60MHz RF signal has the power level that its pulse that adapts to 2MHz RF signal applies state.

Fig. 6 shows the situation according to another embodiment of the present invention, and wherein 27MHz RF signal and 60MHz RF signal have the power level that its pulse that adapts to 2MHz RF signal applies state.

Fig. 7 shows the specimen page that is described as follows true concept map: under certain conditions, non-base stage RF generator can not be at power demand set point output RF power.

Fig. 8 show according to the embodiment of the present invention for learning when base stage RF generator applies pulse the method for the RF frequency of the optimal tuning of non-base stage RF generator.

Fig. 9 show according to the embodiment of the present invention when providing pulse base stage RF signal and at least one non-base stage RF signal when plasma chamber by optimum RF power delivery the method to the plasma load of plasma chamber.

Embodiment

Referring now to some execution modes as shown in the drawing of the present invention, describe the present invention.In the following description, many details are stated to provide thorough understanding of the present invention.But it is evident that, to those skilled in the art, the present invention can be in the situation that do not have some or all in these details to be implemented.On the other hand, known processing step and/or structure can not be described in detail to avoid unnecessarily fuzzy the present invention.

Various execution modes be will describe below, method and technology comprised.Should keep firmly in mind, the present invention also can be contained the manufacture object that comprises computer-readable medium, and on computer-readable medium, storage is for implementing the computer-readable instruction of the technology of the present invention.Computer-readable medium can comprise for storing the computer-readable medium of for example semi-conductive, magnetic, optomagnetic, light or other form of computer-readable code.Further, the present invention also can be contained for implementing the device of embodiments of the present invention.Such device can comprise that special use and/or programmable circuit are to carry out the task about embodiments of the present invention.The embodiment of such device comprises all-purpose computer and/or the suitable dedicated computing equipment after programming and can comprise computer/computing equipment and be applicable to the combination about the special use/programmable circuit of the various tasks of embodiments of the present invention.

Embodiments of the present invention relate to for by front take the photograph arrange one or more upper frequency RF signal RF power level and front take the photograph ground control impuls apply the method and apparatus of controlling plasma treatment with the RF power perturbation of minimization process.The power level of upper frequency RF signal is determined and is followed in response to base stage pulsed RF signal to be arranged respectively.In other words, the power level of upper frequency RF signal is determined and is followed and arranged respectively for the high impulse of base stage pulsed RF signal and for the low pulse of base stage pulsed RF signal.

As the term being adopted herein, the representative of base stage pulsed RF signal applies the low-limit frequency RF signal of pulse.For example, if bottom electrode is provided three RF signals (2MHz, 27MHz and 60MHz) and 2MHz RF signal applies pulse, 2MHz RF signal represents base stage pulsed RF signal, because it is the low-limit frequency RF signal that applies pulse.As another example, if plasma processing chamber is provided three RF signals and gives its bottom electrode (2MHz, 27MHz and 60MHz) and 2MHz RF signal with continuous wave (, non-pulse pattern) operation and 27MHz RF signal and 60MHz RF signal apply pulse, 27MHz RF signal represents base stage pulsed RF signal.

In order to illustrate term, base stage pulsed RF signal can be identical or different with main RF signal, and main RF signal represents the RF signal that independently applies pulse.When a plurality of RF power supplys apply pulse, the one in described RF power supply can be designated as main RF power supply and independently make its main RF signal pulse.Main RF power supply can send control signal and give other RF power supply so that apply impulsive synchronization.Do not require the RF signal that main RF signal is low-limit frequency.Therefore, 27MHz pulsed RF signal can be used as the main RF signal of 2MHz pulsed RF signal, and vice versa.But term as used herein base stage pulsed RF signal is the low-limit frequency RF signal that applies pulse.It should be noted in the discussion above that in this and use main RF power supply lock-out pulse between RF power supply to apply a kind of method that just makes to apply impulsive synchronization.For example can adopt the pulse between the synchronous all RF power supplys of external circuit to apply.

In one or more execution mode, when base stage RF signal applies pulse, each in other pulsed RF signal before the pulse of itself and base stage pulsed RF signal applies between the first default power level of state synchronized and the second default power level alternately with taking the photograph.The first default power level represents the power level that the high impulse for base stage RF signal of other pulsed RF signal is established.The second default power level represents the power level that the low pulse for base stage RF signal of other pulsed RF signal is established.

For example, suppose plasma processing chamber be provided three RF signals give its bottom electrode (2MHz, 27MHz and 60MHz) and 2MHz and 27MHz RF signal the two all with 100Hz, apply pulse.2MHz base stage pulsed RF signal can apply pulse with 100Hz between 2MHz high power levels and 2MHz low-power level.27MHz RF signal response is taken the photograph and is replaced between the first default power level (it occurs in response to 2MHz high power levels) and the second default power level (it occurs in response to 2MHz low-power level) before the control signal meeting that comes autonomous RF power supply or external sync control circuit.

The default power level of non-base stage pulsed RF signal (such as the 27MHz RF signal in previous embodiment) is determined and/or is established to reach the result of some hope.Further, each in first of non-base stage pulsed RF signal the default power level and the second default power level all applies state for each pulse of base stage pulsed RF signal independently and establishes.So, they are determined and/or establish for the condition of plasma being present in during the high state of base stage RF signal (such as the 2MHz RF signal in previous embodiment) and the low state of base stage RF signal independently.For example, once these default power levels (are established for non-base stage RF signal, in formula forming process), when base stage pulsed RF signal applies pulse between its high state and its low state, non-base stage RF signal response in come autonomous RF power supply or from the control signal of external sync control circuit in process of production (for example,, in substrate processing process) between the first default power level and the second default power level alternately.The another kind of form of presentation of this situation is that non-base stage pulsed RF signal response not only depends on the state (high or low) that base stage RF signal applies the true of pulse but also depends on base stage RF signal.

In one or more execution mode, frontly take the photograph response and be used to optimize pulse and apply the unstable of RF power in process.Before the term adopting herein, take the photograph or frontly take the photograph response and refer to that the compensation of RF signal and/or pulse apply front to be taken the photograph and carry out rather than carry out reactively.As previously discussed, reactive response detects when condition of plasma (for instance, such as plasma impedance) in chamber changes because the pulse of the one in other RF signal applies and occurs at matching network or with the RF power supply of RF signal correction connection.In reactive response modes, after such detection occurs, this matching network or this RF power supply respond to compensate the condition of plasma detecting and change.Specifically,, in reactive response modes, matching network or RF power supply only respond after detection is made.

Compare, front taking the photograph in response modes, the response of the matching network of other RF signal or RF power supply is front started by control signal with taking the photograph and is not needed etc. to be detected.For example, external control circuit and/or processor and/or computer can before take the photograph the knowledge that based on it, one or more pulse in other RF signal is applied to behavior/sequential with instruction matching network or RF power supply that transmits control signal and respond.The generation of this control signal and response does not need to wait for that the detection that condition of plasma that paired pulses is relevant changes occurs.As another embodiment, thereby can communicate by letter to provide control signal to start response by other RF generator with other RF generator for the RF generator of the one of pulsed RF signal.In this case, the RF generator that sends control signal can be as main RF generator, and other RF generator is as from RF generator.The detection that replacement changes in response to article on plasma concrete conditions in the establishment of a specific crime, before main RF generator, take the photograph send control signal to it from RF generator.

By front taking the photograph, control the response of matching network and/or the response of other RF generator, because pulse applies the unstable and/or plasma perturbation of the RF power coming, on the duration and/or in intensity, reduced.By this way, power perturbation is reduced and plasma stability is strengthened.

With reference to accompanying drawing and discussion below, can understand better the feature and advantage of embodiments of the present invention.

Fig. 2 shows the capacitance coupling plasma treatment system 202 of the simplification with plasma processing chamber 204 according to the embodiment of the present invention.Although typical plasma process system can have a plurality of chambers, for the object of setting forth only shows Yi Ge chamber.Omitted in addition and well known to a person skilled in the art other details, such as machine transferring arm, Storage Box, gas supply, etc.

In the embodiment of Fig. 2, top electrode 206 is grounded, and the bottom electrode 208 that represents substrate holder (substrate holder) or chuck is provided respectively three the RF signals (2MHz, 27MHz and 60MHz) from three RF power supplys 220,222 and 224 by matching network 230.Although show three RF signals and three RF power supplys, bottom electrode 208 can be provided few to one or and desirable as many RF signal.Further, although selected 2MHz in order to set forth, the RF frequency of 27MHz and 60MHz, if need also can use different RF frequencies.Described plasma processing chamber 204 is arranged to dielectric etch.

As is known to the person skilled in the art, matching network 230 mates the impedance of RF power supply 220,222 and 224 with minimum reflected power and maximum power output with the impedance of plasma load in plasma processing chamber.According to the embodiment of the present invention, if RF power supply 220,222 makes one in RF power supply as RF pulse main power source in communicating by letter with 224, this RF power supply can before take the photograph and transmit control signal to other RF signal so that the front pulse that starts these other RF signals applies with taking the photograph.

For example, RF power supply 220(2MHz RF power supply) can be used as pulse main power source and send numerals or analog control signal (for instance to respectively

RF power supply

222 and 224 via

conduit

230 and 232, it can be the signal of telecommunication or light signal) with instruction

RF power supply

222 and 224, their pulse is applied with the pulse of main 2MHz RF signal and applied (for instance, rising edge during applying with 2MHz RF pulse, trailing edge or any scheduled time) synchronize, and needn't wait for the detection that the condition of plasma in plasma process chamber 204 changes.

As another embodiment, RF power supply 222(27MHz RF power supply) can be used as pulse main power source and send numerals or analog control signal (for instance to respectively

RF power supply

220 and 224 via

conduit

234 and 232, it can be the signal of telecommunication or light signal) with instruction

RF power supply

220 and 224, their pulse is applied with the pulse of main 27MHz RF signal and applied (for instance, rising edge during applying with MHz RF pulse, trailing edge or any scheduled time) synchronize, and needn't wait for the detection that the condition of plasma in plasma process chamber 204 changes.

Alternatively, control circuit 250 can be utilized for all three RF power supplys 220,222 and 224 control signal is provided, as shown.In this case, do not have RF power supply can need to serve as main power source and all can from control circuit 250 receives, take the photograph the control signal that ground instruction RF power supply applies pulse.The pulse of controlling each RF signal by front taking the photograph applies, and RF power perturbation is minimized, as shown in Fig. 3 below.

Fig. 3 shows the figure of the power output with respect to the time of two RF signals: 2MHz RF signal 302 and 60MHz RF signal 304.2MHz RF signal 302 applies pulse with 50% duty ratio at 100Hz between 2500W and 0W.Clear in order to set forth, in the embodiments of figure 3, the duration that 60MHz RF signal 304 being with its high impulse for 2MHz RF signal, be set in the second default power level that is set in equally 900W during the first default power level of 900W and its low pulse persistance for 2MHz RF signal.In the embodiments of figure 3, produce the 2MHz of these RF signals that apply pulse and 60MHz RF power supply the two all from public control circuit (such as the control circuit 250 of Fig. 2) thus reception control signal apply pulse and without the detection of waiting for that article on plasma concrete conditions in the establishment of a specific crime changes to take the photograph the method for synchronization.Alternatively, one in RF power supply (for example, 2MHz RF power supply or 27MHz RF power supply) can be used as for the pulse main power source of other RF power supply and can before take the photograph and send that control signal synchronously applies pulse substantially with other RF power supply of instruction and without the detection of waiting for that article on plasma concrete conditions in the establishment of a specific crime changes.

As seen from Figure 3, for each height-low or low-Gao transformation of 2MHz base stage pulsed RF signal 302, the power perturbation in 60MHz RF signal 304 is held obviously lower (in the embodiments of figure 3 lower than 3%).These are illustrated by reference number 320,322,324 and 328.Compared to 60MHz RF power supply wherein, in pattern of reactivity, move the situation in the Fig. 2 of (that is, the detection changing in response to condition of plasma and compensate), the RF power perturbation is here obviously less.Once this is because power level set point is determined for non-base stage pulsed RF signal, non-base stage pulsed RF signal can apply pulse and without postponing based on reception control signal between two power setting point, thereby contributes to more stable RF power stage.

In one or more execution mode, non-base stage pulsed RF signal (, higher RF frequency pulse signal) the first power level and each in the second power level can dynamically be determined from one or more measurable plasma processing chamber parameter (for instance, such as chuck is setovered or return to RF electric current).By " dynamically ", should be understood that, this of power level for example determined and can during formula formation or verification of machine, on algorithm, be done, or can in processing procedure, instant (on-the-fly) complete.The first power level of non-base stage pulsed RF signal (corresponding to the power level when base stage pulsed RF signal non-base stage pulsed RF signal during in its high state) can automatically be determined by algorithm and calculate for the high state of base stage pulsed RF signal from the sensor measurement of one or more plasma processing chamber parameter.Similarly, the second power level of non-base stage pulsed RF signal (corresponding to the power level when base stage pulsed RF signal non-base stage pulsed RF signal during in its low state) can automatically be determined by algorithm and calculate for the low state of base stage pulsed RF signal from the sensor measurement of one or more plasma processing chamber parameter.

In this case, during the high state and low state of base stage RF pulse signal, utilize the computer of for example sequencing, sensor measurement based on one or more plasma processing chamber parameter is dynamically determined and non-base stage pulsed RF signal is set (, upper frequency pulsed RF signal) power level has represented an advantage to reach the ability of the technological parameter of hope, because the power level at the upper frequency pulsed RF power signal during the high state of base stage pulsed RF signal and during the low state of base stage pulsed RF signal is the independent control knob for technique now.Afterwards, non-base stage pulsed RF signal is according to being converted to the second predefine power level (vice versa) from the first predefine power level simply from main RF power supply or for example, from peripheral control unit (, the controller circuitry 250 of Fig. 2) reception control signal.

Be noted that the first predefine power level and the second predefine power level are specific for each RF power supply.In other words, 27MHz power supply can have specific (RF-power-supply-specific) power level of the first predefine RF power supply and the second predefine RF power supply certain power level of himself, and 60MHz RF power supply that can there is himself from the first different predefine RF power supply certain power level and the second predefine RF power supply certain power level 27MHz RF power supply.

In one or more execution mode, utilize computer, the sensor measurement based on one or more plasma processing chamber parameter (such as chuck biasing) of for example sequencing, the power level of base stage pulsed RF signal (that is, high impulse power level and low pulse power level) also can dynamically be determined to reach the technological parameter (such as deposition) of hope.Utilize computer, the sensor measurement based on one or more plasma processing chamber parameter of for example sequencing dynamically to determine that the power level of base stage pulsed RF signal has represented an advantage to reach the ability of the technological parameter of hope, because the power level of base stage pulsed RF power signal is the control knob for technique now.

Fig. 4 shows situation according to an embodiment of the present invention, and wherein 2MHz RF signal 402 carries out pulse with 100Hz with 50% duty ratio and applies between 2500W and 0W.60MHz RF signal 404 was taken the photograph mode in the past and was synchronously made the high state for 2MHz RF signal, and the power level of 60MHz RF signal is at 900W and during the low state of 2MHz RF signal, the power level of 60MHz RF signal is 450W.Be noted that, each in these two power levels of 60MHz RF signal in view of base stage RF pulse signal (for example, 2MHz RF signal) process results (such as low polymer deposition, the wafer bias that reduces, etc.) of hope is determined respectively and arranged and determined and arrange to reach to concrete state (high or low).In addition, before applying, the pulse of two RF signals of Fig. 4 occurs with taking the photograph, that is, without the detection of waiting for the detection of change of article on plasma concrete conditions in the establishment of a specific crime or the change of one or more chamber parameter of this condition of plasma change that reflection is come because of base stage RF signal pulse.So, RF power perturbation and RF plasma unstable are greatly reduced.

Fig. 5 shows the situation according to another embodiment of the present invention, and wherein 2MHz RF signal 502 carries out pulse and applies between 2500W and 0W with 50% duty ratio at 100Hz.60MHz RF signal 504 was taken the photograph mode in the past and was synchronously made the high state for 2MHz RF signal, and the power level of 60MHz RF signal is at 900W.During the low state of 2MHz RF signal, the power level of 60MHz RF signal is raised to 1125W.Fig. 4 and Fig. 5 illustrate that the power level of non-base stage RF signal (that is, upper frequency pulsed RF signal) can be higher or lower after base stage pulsed RF signal is converted to low state from high state.Again, be noted that, each in these two power levels of 60MHz RF signal in view of base stage RF pulse signal (for example, 2MHz RF signal) process results (such as low polymer deposition, the wafer bias that reduces, etc.) of hope is determined and arranged and determined and arrange to reach to concrete state (high or low).In addition, before applying, the pulse of two RF signals of Fig. 4 occurs, that is with taking the photograph, and and without the detection of waiting for the change of article on plasma concrete conditions in the establishment of a specific crime.So, RF power perturbation and RF plasma unstable are greatly reduced.

Fig. 6 shows the situation according to another embodiment of the present invention, and wherein 2MHz RF signal 602 carries out pulse with 100Hz with 50% duty ratio and applies between 2500W and 0W.60MHz RF signal 604 was taken the photograph mode in the past and was synchronously made the high state for 2MHz RF signal, and the power level of 60MHz RF signal is at 500W.During the low state of 2MHz RF signal, the power level of 60MHz RF signal is raised to 625W.27MHz RF signal 606 was taken the photograph mode in the past and was synchronously made the high state for 2MHz RF signal, and the power level of 27MHz RF signal is at 1000W.During the low state of 2MHz RF signal, the power level of 27MHz RF signal is lowered to 250W.Again, be noted that, each in these two power levels of 60MHz RF signal and and these two power levels of 27MHz RF signal in each in view of base stage RF pulse signal (for example, 2MHz RF signal) process results (such as low polymer deposition, the wafer bias that reduces, etc.) of hope is determined and arranged and determined and arrange to reach to concrete state (high or low).

In the embodiment of Fig. 6, one of RF power supply (such as 2MHz RF power supply, 27MHz RF power supply or 60MHz RF power supply) can be used as main power source and can transmit control signal to other RF power supply took the photograph in the past ground lock-out pulse apply.Alternatively, external control circuit can be used as main signal and can transmit control signal to all three RF power supplys took the photograph in the past ground lock-out pulse apply.

As described in, the RF power level of each RF signal is can be by tuning to realize the process results of wishing respectively during the high state of base stage pulsed RF signal and during the low state of base stage pulsed RF signal.As embodiment, what can believe is to increase ion energy by improving the RF power level of 2MHz RF signal.It is useful increasing ion energy, also can cause in some cases unnecessary excessive polymer deposition.2MHz RF signal applies pulse in its optimum pulse frequency and best high RF power level and best low RF power level and can cause increasing ion energy and but do not suffer excessive polymer deposition.

Once the optimum RF power level of base stage pulsed RF signal is determined and/or is arranged, non-base stage pulsed RF signal (, upper frequency pulsed RF signal) RF power level can be determined respectively and arrange with further tuning technique (such as tuning plasma density, larger because the power level of upper frequency RF signal is easy to plasma Effects of Density) for the high state of base stage pulsed RF signal and the low state of base stage pulsed RF signal.Like this these different RF pulses apply the different RF power level of signal can be as the discrete control knob of technique.

As described in, due to each pulsed RF signal, front to be taken the photograph ground synchronous, so RF power perturbation is minimized.Even if being filled a prescription, RF signal (such as 60MHz RF signal) is defined as with continuous wave (CW) mode operation, in one embodiment, this RF signal is set and with the high state at base stage pulsed RF signal (such as 2MHz RF signal), takes the photograph that to apply pulse can be also to wish identical power level (such as 900W) is front during the two, because as shown in Figure 3, compared to reactivity shimming method, at equal-wattage level, apply pulse like this and reduced RF power perturbation.

In one or more execution mode, the RF power level of base stage pulsed RF signal and non-base stage RF signal is set such that plasma applies in process and is maintained in pulse.In other words, plasma is not extinguished during the low state of base stage pulsed RF signal and/or the low state of non-base stage pulsed RF signal.Keep plasma ignition to make the technique button (as previously mentioned) of technology controlling and process by independent RF power level be used more efficiently and also make plasma disturbance minimize because plasma wipe combustion and/or light (if plasma is allowed to extinguish, it can be necessary wiping combustion and/or light) to the control of technique not as continuumpiston good.So, repeatability and uniformity are enhanced.

In one or more execution mode, therefore bimodulus (bimodal) automatic frequency tuning technology and device are disclosed.In bimodulus automatic frequency tuning method, when base stage RF signal is during from a kind of state pulse to another kind of state, the tuned frequency of non-base stage RF signal is front changed to guarantee efficient and stable power stage for each state of base stage RF signal with taking the photograph.

Specifically the RF frequency that, modern RF power supply can tuning its conveying for example, to improve power stage (, being fed to the RF frequency of load by change).As an example, 60MHz RF generator can by its tuning RF frequency shift for example 5-10%(, will flow to the +/-5%-10% of the RF frequency shift 60MHz of load).

But such frequency shift is that the response afterwards when its transducer detects the amount change of the RF power that flows to load is carried out as RF generator so far.This detection often depends on for example measurement result of the ratio (also referred to as gamma) of reflection power and forward power.When RF generator (for example, based on some default gamma threshold values) detects the situation that is characterized as poor efficiency power stage, RF generator can in frequency tuning scheme, change its tuning RF frequency in case more efficiently by power delivery to load.

Yet the person's character afterwards of current frequency tuning scheme often means when plasma impedance or plasma load change to be had and delays in response.In this time of delay, under some condition (such as when base stage RF signal is during from a kind of state pulse to another kind of state), non-base stage RF generator can be very poor efficiency or can not be at required power setting point (by formula regulation) transmission power until non-base stage RF generator its tuned frequency is changed into and is enough to the adaptive plasma load changing.

According to one or more execution mode of the present invention, the tuned frequency of non-base stage RF signal for example, is determined in advance for each pulse condition (, high or low) of base stage RF signal.Consider this situation, for example, when 2MHz base stage RF signal is when approximately 1kHz applies pulse with 50% duty ratio.For example, in learning phase, confirmable, when 2MHz base stage RF signal in its low pulse condition (, pulse is to after low) time, the power stage of 60MHz RF generator is efficient when in fact 60MHz RF generator uses 61MHz tuned frequency to carry its RF power.Further, confirmable, in another embodiment, in learning phase, for example, when 2MHz RF signal is when its high impulse state (, pulse is after height), 60MHz RF generator is efficient when in fact 60MHz RF generator uses 59MHz tuned frequency to carry its RF power.

In one or more execution mode, in process of production, 60MHz RF generator (being non-base stage RF generator in this embodiment) changes its tuned frequency understanding when base stage RF signal is from a kind of state pulse to another kind of state with taking the photograph.Before this frequency shift can be described as, take the photograph, because the change of non-base stage RF generator on tuned frequency is not pulse based on to because of base stage RF signal, do not apply the detecting and making afterwards by the change on the condition of plasma of 60MHz RF generator identification or the change in impedance of coming.

On the contrary, the change of non-base stage RF generator in tuning RF frequency synchronously made this change occur at base stage RF signal, to guarantee enough and/or efficient power stage during from a kind of state pulse to another kind of state at Best Times.For example, based on coordinating signal (any one that it can be in 2MHz RF generator or RF generator or sent by the independent control circuit of coordinating RF generator) but not wait for the pulse because of base stage RF signal is applied to change on the condition of plasma of being identified by 60MHz RF generator that comes or the detection of the change in impedance, 60MHz RF generator can before change its RF tuned frequency with taking the photograph.Generally speaking, even non-base stage RF generator can change before this its tuned frequency when base stage RF signal is from a kind of pulse condition pulse to another kind of pulse condition.

Fig. 7 shows the specimen page that is described as follows true concept map: under certain conditions, non-base stage RF generator can not be at power demand set point output RF power.This is situation of the prior art, for example.In the embodiment of Fig. 7, base stage 2MHz RF generator has the power setting point (not showing in Fig. 7) of 9kW, and 60MHz RF generator has the power setting point of 750W.For each RF generator, these are the power levels of wishing.Further, in the embodiment of Fig. 7, base stage 2MHz RF signal continues 5 seconds (from 2.2 seconds to 7.2 seconds) from high state gradual change (ramp) to low state.

In Fig. 7, the amount of the power that left vertical pivot representative is carried by 60MHz RF generator, and right vertical pivot represents the tuned frequency of 60MHz RF generator.Two vertical pivots are marked and drawed with respect to horizontal time axis.The RF power quantity that line 702 representatives are carried.Line 730 represents the tuned frequency of 60MHz RF generator.

Putting 700,2MHz RF generator in high impulse state.At this point, 60MHz RF generator is carried its power (line 730 of time t=2 during second) efficiently in the tuning RF frequency of about 61MHz.

When the time is 2.2 seconds, 2MHz base stage RF signal starts down gradually to fall (ramp low), arrives its low state in the time of 7.2 seconds.From RF power line 702, the change of 60MHz RF generator sensing plasma load also attempts to maintain the power setting point of its 750W.At certain time point, start from locating for approximately 5 seconds (putting 704), 60MHz RF generator starts to change its tuned frequency downwards to improve the efficiency of RF power stage in response to the change (it gradually drops to low state by 2MHz base signal and causes) of the plasma load detecting.

When the time is 7.2 seconds (reference number 706 on horizontal time axis), 2MHz base stage RF signal is in its low state.Visible in Fig. 7, the RF power quantity of being carried by 60MHz RF generator drops to about 220W from putting 708 to point 710 temporarily.This RF power quantity of being carried by 60MHz RF generator is significantly lower than the 750W power setting point for 60MHz RF generator.This has represented unfavorable condition.

From putting 706 to point 712,60MHz RF generators, seek the tuning RF frequency that can in its low pulse condition, 60MHz RF power be carried at required 750W power setting point with 2MHz RF signal.At point 714,60MHz RF generator, be stabilized to the tuning RF frequency of about 59.75MHz.In this lower tuning RF frequency, 60MHz generator can be carried RF power at the set point of its 750W again.

The specimen page of the concept map of Fig. 7 shows for each pulse condition of 2MHz base signal, is useful on the optimal tuning RF frequency of 60MHz RF generator.Further, if 60MHz generator in mode afterwards (, detecting after pulse because of 2MHz base stage RF signal applies the change of the plasma load coming, shown in Fig. 7) change its tuning RF frequency, can there is following situation: power setting point and RF frequency so consequently 60MHz RF generator can not meet its required power setting point.This is shown in Figure 7 between

point

706 and 712.

Fig. 8 show according to the embodiment of the present invention for learning when base stage RF generator applies pulse the method for the RF frequency of the optimal tuning of non-base stage RF generator.In step 802, with pulse base stage RF signal and at least one non-base stage RF signal excitation (power) plasma chamber.In step 804, with automatic tuning pattern, operate non-base stage RF generator so that non-base stage RF generator can be searched the optimum RF frequency (f1 and f2) of its high state and low state that is respectively used to base stage RF signal.With this automatic tuning pattern, during each state of base stage RF signal, non-base stage RF generator is allowed to search the tuning RF frequency of himself.For these optimum RF frequencies (for non-base stage RF signal) of each state of base stage RF signal, as predefine RF frequency, and non-base stage RF generator is taken the photograph before when base stage RF signal applies pulse and is switched to another predefine RF frequency from a predefine RF frequency.

The term adopting herein refers to such RF frequency for the optimum RF frequency of non-base stage RF generator: in this RF frequency, non-base stage RF generator can be desirably or carried efficiently its power (according to certain predefined standard) and/or can meet its power stage set point.As discussed here, there are at least two for the optimum RF frequency of non-base stage generator.These two optimum RF frequencies are corresponding to two alternating states of base stage RF signal.

Be noted that the first predefine RF frequency and the second predefine RF frequency that in production process, adopt are specific to each RF power supply.In other words, 27MHz power supply can have the first predefine RF power supply specific (RF-power-supply-specific) RF frequency and the specific RF frequency of the second predefine RF power supply of himself, and 60MHz RF power supply can have those the specific RF frequency of the first predefine RF power supply and the specific RF frequency of the second predefine RF power supply that is different from 27MHz RF power supply of himself.

All other conditions in one or more execution mode Zhong， chamber are preferably set such that they as far as possible closely simulate the condition while producing.In another embodiment, the frequency of non-base stage RF generator can manually be changed with (for example,, by measuring gamma) definite respectively for the high state of base stage RF signal and optimum frequency f1 and the f2 of low state.

In step 806, for the high state of base stage RF signal and these best non-base stage RF frequency generators of low state, can be recorded and/or store in (that is, the non-base stage RF frequency generator of the best in learning phase by the production of the substrate after acquistion) process, to use producing.In process of production, when base stage RF signal applies pulse, before non-base stage RF generator, take the photograph and between optimum RF frequency f 1 and optimum RF frequency f 2, switch rather than wait for the detection of the change of plasma impedance or gamma.

Fig. 9 show according to the embodiment of the present invention when being provided with pulse base stage RF signal and at least one non-base stage RF signal when plasma chamber by optimum RF power delivery the method to the plasma load of plasma chamber.In step 902, with pulse base stage RF signal and at least one non-base stage RF signal excitation (power) plasma chamber.In step 904, with non-automatic tuning pattern, operate non-base stage RF generator.In step 906, the front frequency of taking the photograph synchronous non-base stage RF signal switches and the pulse of base stage RF generator applies.That before this, takes the photograph synchronously makes when base stage RF signal applies pulse between its high state and its low state, and non-base stage RF generator can switch its tuned frequency between the optimal tuning frequency f 1 of acquistion in advance and the optimal tuning frequency f 2 of acquistion in advance.The switching of the tuned frequency of non-base stage RF generator can be described as before takes the photograph in process of production, because this handoff response is performed and is independent of the plasma load condition sensing (that is, to reflecting that this pulse because of base stage RF signal applies the detection of change of chamber parameter of the plasma load condition of the change coming) of change in synchronizing signal.

This synchronizing signal can be for example by base stage RF generator, any RF generator in a plurality of RF generators or sent by external sync circuit or computer.In execution mode, when base stage RF signal is switched to another kind of state from a kind of state, before non-base stage RF generator, takes the photograph and be switched to the optimum RF frequency f 2 of another acquistion in advance from the optimum RF frequency f 1 of an acquistion in advance.

For example, if the high state of base stage RF signal is determined to be efficiently and for the optimum RF frequency f 2 of the acquistion in advance of non-base stage RF generator, the low state of base stage RF signal is determined to be efficiently for the optimum RF frequency f 1 of the acquistion in advance of non-base stage RF generator, non-base stage RF generator can be switched in response to synchronizing signal the optimum RF frequency f 1 of acquistion in advance during to high state in the pulse of base stage RF generator.Further, non-base stage RF generator can be switched in response to synchronizing signal the optimum RF frequency f 2 of acquistion in advance during to low state in the pulse of base stage RF generator.

In another embodiment, non-base stage RF generator can before take the photograph and be switched to the optimum RF frequency f 2 of another acquistion in advance from the optimum RF frequency f 1 of an acquistion in advance, even slightly before base stage RF signal is switched to another kind of state from a kind of state.

In another embodiment, even slightly at base stage RF signal after a kind of state is switched to another kind of state, non-base stage RF generator can before take the photograph and be switched to the optimum RF frequency f 2 of another acquistion in advance from the optimum RF frequency f 1 of an acquistion in advance.

In one or more execution mode, the non-base stage RF signal frequency of taking the photograph before non-base stage RF generator is switched (for example,, between the RF of acquistion in advance frequency f 1 and the RF frequency f 2 of acquistion in advance) and can be combined to improve delivery efficiency and the stability of RF power when base stage RF signal applies pulse with the power level setting of taking the photograph before non-base stage RF generator.In one or more execution mode, the power level of taking the photograph before the frequency switching of taking the photograph before non-base stage RF signal and/or non-base stage RF generator is switched and can be applied and synchronize with the pulse of base stage RF signal.If comprise a plurality of non-base stage RF signals, the frequency of these non-base stage RF signals and/or power level can be utilized as similarly switching before when being arranged on base stage RF signal and applying pulse that the situation for single non-base stage RF signal is discussed with taking the photograph.

From the above, embodiments of the present invention have been improved stability and the efficiency of the RF power stage when base stage RF signal applies pulse between its high state and its low state.By front changing a non-base stage RF generator or a plurality of non-base stage RF generator RF power level of (if comprising a plurality of non-base stage RF generators) with taking the photograph, when base stage RF signal applies pulse between its high state and its low state, the stability of power stage is improved.By front taking the photograph, between the optimum RF frequency of the acquistion in advance of non-base stage RF generator or a plurality of non-base stage RF generator (if comprising a plurality of non-base stage RF generators) for, switch, the efficiency of power stage is improved or makes for each pulse condition of base stage RF signal or feasible for the power stage of the height around from base stage RF-duration that low and low-Gao changes.

By these extra control knobs are provided, technical recipe window can be opened to adapt to stricter technological requirement, leads improved treatment and the yield of high density/high performance device.

Although the present invention is described with some preferred implementations, also have alternative, substitute mode and equivalent way within the scope of the invention.It should be noted in the discussion above that implementing method and apparatus of the present invention has many alternative methods.Although a plurality of embodiment are provided herein, it is intended that these embodiment is illustrative and unrestricted the present invention.

Claims

1. for process a method for substrate at the plasma processing chamber with at least one electrode, described plasma processing chamber has and is coupled a plurality of RF power supplys that a plurality of RF signals are provided for described electrode, and described method comprises:

Make base stage RF pulse signal between high power levels and low-power level, apply pulse with the first pulse frequency, described base stage RF pulse signal represents a RF signal of the minimum pulse frequency in the pulse frequency in described a plurality of RF signal with described a plurality of RF signals, and described the first pulse frequency is different from the RF frequency of described base stage RF pulse signal;

Control signal is at least sent to the subset of described a plurality of RF power supplys, wherein when processing described substrate, described control signal is not to need taking the photograph and produce owing to applying the change of one or more chamber parameter that pulse comes described in described base pulse signal and carry out before the mode of sensing; And

In response to described control signal, in the first predefine RF power supply certain power level be different between the second predefine RF power supply certain power level of described the first predefine RF power supply certain power level, make each in the described subset of a plurality of described RF power supplys apply pulse.

2. the method for claim 1, wherein said control signal is launched from one of described a plurality of RF power supplys.

3. the method for claim 1, wherein said control signal is from the outside main control circuit transmitting of described a plurality of RF power supplys.

4. the method for claim 1, the described subset of wherein said a plurality of RF power supplys does not comprise the RF power supply that makes described base stage RF pulse signal apply pulse.

5. the method for claim 1, wherein the RF power generation in the described subset of a plurality of RF power supplys has the RF signal of different RF frequency.

6. the method for claim 1, wherein said the first predefine RF power supply certain power level produces during the described high power levels of described base stage RF pulse signal.

7. the method for claim 1, wherein said the second predefine RF power supply certain power level produces during the described low-power level of described base stage RF pulse signal.

8. the method for claim 1, the described low-power level of wherein said RF pulse signal represents zero energy.

9. the method for claim 1, wherein said the second predefine RF power supply certain power level represents zero energy.

10. the method for claim 1, the described low-power level of wherein said RF pulse signal represents non-zero power.

11. the method for claim 1, wherein said the second predefine RF power supply certain power level represents non-zero power.

12. 1 kinds for process the method for substrate at the plasma processing chamber with at least one electrode, and described plasma processing chamber has and is coupled a plurality of RF power supplys that a plurality of RF signals are provided for described electrode, and described method comprises:

In response to described control signal, in the first predefine RF power supply certain power level be different between the second predefine RF power supply certain power level of described the first predefine RF power supply certain power level, switch the RF frequency of the RF signal of each output in the described subset of a plurality of described RF power supplys.

13. methods as claimed in claim 12, wherein said control signal is launched from one of described a plurality of RF power supplys.

14. methods as claimed in claim 12, wherein said control signal is from the outside main control circuit transmitting of described a plurality of RF power supplys.

15. methods as claimed in claim 12, the described subset of wherein said a plurality of RF power supplys does not comprise the RF power supply that makes described base stage RF pulse signal apply pulse.

16. methods as claimed in claim 12, wherein the RF power generation in the described subset of a plurality of RF power supplys has the RF signal of different RF frequency.

17. methods as claimed in claim 12, wherein said the first predefine RF power supply certain power level produces during the described high power levels of described base stage RF pulse signal.

18. methods as claimed in claim 12, wherein said the second predefine RF power supply certain power level produces during the described low-power level of described base stage RF pulse signal.

19. methods as claimed in claim 12, the described low-power level of wherein said RF pulse signal represents zero energy.

20. methods as claimed in claim 12, wherein said the second predefine RF power supply certain power level represents zero energy.

21. methods as claimed in claim 12, the described low-power level of wherein said RF pulse signal represents non-zero power.

22. methods as claimed in claim 12, wherein said the second predefine RF power supply certain power level represents non-zero power.

23. methods as claimed in claim 12, wherein the RF power supply in the described subset of a plurality of described RF power supplys operates with non-automatic tuning pattern in described processing procedure.