JP2009130267A - Method and device for controlling process gas concentration in plasma reactor processing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately control a process gas concentration in a process chamber with a desired concentration profile under a restriction of an upper limit of the flow rate of a given supply gas in a plasma reactor process system having a specific equipment specification. <P>SOLUTION: A standard curve showing the relationship between a concentration of the known process gas concentration and an emission plasma intensity of a diluted gas or process gas is created. By using this, a pulse response characteristic showing the relationship between the pulsating change of the gas supply amount and the pulsating response accompanying therewith of the gas concentration is calculated, and a model defining the relationship between the change in the gas supply amount and the change in gas concentration is created. The optimum flow rate value change is calculated by substituting the desired process gas concentration change to a functional determinant created by using this model showing the relationship between the supply amount change and the concentration change, and the operation is conducted by applying this to the actual plasma reactor system. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method and apparatus for controlling a process gas concentration in a process chamber in a plasma reactor processing system suitable for manufacturing, for example, a liquid crystal device or a semiconductor device.

This type of plasma reactor processing system includes a process chamber containing a plasma generator (for example, a parallel plate electrode system, a microwave antenna system, etc.) and one or more types of dilution gas sources (for example, Ar, Kr, Xe, etc.) and a dilution gas supply line connecting the process chamber and one or more process gas sources (for example, H ₂ , O ₂ , NF ₃ , Cl ₂ , SiCl ₄ , HBr). , SF ₆ , C ₅ F ₈ , CF _4, etc.) and a process gas supply line that connects the process chamber, and a chamber gas discharge line that connects the process chamber and a vacuum pump (such as a turbo molecular pump). And have.

  Each supply pipe for each dilution gas and each process gas is provided with a flow rate regulator capable of adjusting the flow rate of the gas flowing through the pipeline to a set value, and is connected to the discharge pipe for the gas in the chamber. Is a pressure controller having a function of automatically changing the opening of the flow control valve in a direction in which a deviation between a given pressure setting value and a pressure measurement value measured via the pressure measurement unit decreases. It is interposed (see, for example, Patent Documents 1 and 2).

By the way, in this kind of plasma reactor processing system, it is necessary to change the concentration of the process gas in the process chamber at the start of the process, during the process, and at the end of the process. For example, at the start of the process, the concentration of the dilution gas from a single atmosphere (process gas concentration 0%) to a mixed atmosphere (process gas concentration X%) of the dilution gas and (one or more types) process gas Changes are needed. In the middle of the process, a mixed atmosphere (process gas concentration X2%) having a concentration of a dilution gas and a process gas from another concentration (process gas concentration X1%) or a mixed atmosphere (gas) having a different gas type is used. It may be necessary to change the concentration to the process gas concentration Xa of the species a and the process gas concentration Xb) of the gas species b. Further, at the end of the process, it is necessary to change the concentration from the mixed atmosphere of the dilution gas and the process gas (process gas concentration X%) to the single atmosphere of the dilution gas (process gas concentration 0%).
Japanese Patent Laid-Open No. 2000-200078 JP 2002-203895 A

  By the way, in a plasma reactor processing system having specific equipment specifications, assuming a case where a plasma process is performed for manufacturing a liquid crystal device, a semiconductor device, etc., the process gas concentration in the process chamber is an object to be manufactured. There is an optimum concentration profile (relationship between concentration and time) according to the characteristics of the gas, the use efficiency of the process gas, and the like.

  That is, depending on the characteristics of the manufacturing object, even if the target process gas concentration after settling is the same, the process gas concentration is brought to the target concentration as soon as possible under the restriction of the upper limit value of the supply gas flow rate. In some cases, the process gas concentration may be gradually raised to the target concentration with a certain elapsed time under the restriction of the upper limit value of the supply gas flow rate.

  The present invention has been made in view of the above-described technical background, and an object of the present invention is to limit the upper limit value of the supplied gas flow rate in a plasma reactor processing system having specific equipment specifications. An object of the present invention is to provide a process gas concentration control method and apparatus capable of precisely controlling the process gas concentration in the process chamber with a desired concentration profile.

  Other objects and operational effects of the present invention will be easily understood by those skilled in the art by referring to the following description of the specification.

  The above technical problem can be solved by a process gas concentration control method and apparatus in a plasma reactor processing system having the following configuration.

  The method of the present invention presupposes a plasma reactor processing system having a certain configuration. This plasma reactor processing system includes a process chamber having a built-in plasma generation unit, a dilution gas supply line connecting the dilution gas supply source and the process chamber, and a process gas connecting the process gas supply source and the process chamber. And a supply pipe for gas in the chamber connecting the process chamber and the vacuum pump.

  Then, in each of the dilution gas supply line and the process gas supply line, the opening of the flow rate adjustment valve is automatically changed in a direction in which the deviation between the given flow rate adjustment value and the flow rate detection value decreases. A flow regulator having the function of intervening is interposed.

  In addition, a pressure controller having a function of automatically changing the opening degree of the flow control valve in a direction in which the deviation between the pressure setting value and the pressure measurement value decreases is interposed in the exhaust pipe for the gas in the chamber. Yes. In addition, the plasma reactor processing system is provided with emission intensity detection means for detecting the plasma emission intensity of the dilution gas or process gas in the process chamber.

  On the premise of such a plasma reactor processing system, the method of the present invention has five steps including first to fifth steps.

  The first step is to maintain a gas pressure in the process chamber that is the same as the gas pressure in the assumed plasma process, and to adjust the process gas concentration in the process chamber to each of a plurality of known concentrations. A plurality of known process gas concentration states obtained in such a manner that a predetermined flow rate setpoint change is given to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line A calibration curve indicating the relationship between the known process gas concentration and the plasma emission intensity of the dilution gas or process gas at that concentration is obtained by obtaining the emission intensity of the dilution gas or process gas in each of the above through the emission intensity detection means. create.

  Here, “and / or” means that it is usually preferable to operate both flow regulators to keep the pressure constant as in the embodiments described later. If the setter responds at high speed, the pressure may be kept constant even if only one flow rate regulator is operated due to its pressure buffering action.

  In the second step, the gas pressure in the process chamber is kept the same as the gas pressure in the assumed plasma process, and the supply amount of the dilution gas or process gas in the process chamber has a predetermined waveform. And a predetermined flow rate set value change is given to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line, and the dilution gas supply amount obtained in this way Alternatively, a change in plasma emission intensity in response to a change in the process gas supply amount is obtained through the emission intensity detection means, and this is converted into a concentration based on the calibration curve created in the first step, thereby diluting. Pulse response characteristics showing the relationship between the pulse-like change in gas supply rate or process gas supply rate and the accompanying dilution gas concentration or process gas concentration pulse response To get.

  In this case as well, “and / or” means that it is usually preferable to operate both flow regulators to keep the pressure constant as in the embodiments described later. If the setter responds at high speed, the pressure may be kept constant even if only one flow rate regulator is operated due to its pressure buffering action.

  In the third step, based on the pulse response characteristic acquired in the second step and the flow rate setting value application interval determined by the product characteristic of each flow rate regulator, the flow rate setting value change to be given to each flow rate setter is determined. A model that defines the relationship between the time-division instantaneous value and the time-division instantaneous value of the process gas concentration change in the process chamber is created.

  In the fourth step, the time-division instantaneous value of the flow set value change to be applied to each flow setter and the change in the process gas concentration in the process chamber, which are defined using the model created in the third step. By substituting the time-division instantaneous value of the desired process gas concentration change into the function determinant that defines the relationship with the time-division instantaneous value, the time-division instantaneous value of the optimal flow set value change to be given to each flow setter To get.

  In the fifth step, the time-division instantaneous value of the change in the optimum flow rate setting value obtained in the fourth step is applied to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line. To control the process gas concentration in the process chamber so as to obtain a desired change in the process gas concentration.

  According to such a configuration, in the plasma reactor processing system having specific equipment specifications, the process gas concentration in the process chamber is set to a desired concentration profile under the restriction of the upper limit value of the supplied supply gas flow rate. It becomes possible to control precisely.

  In a preferred embodiment of the present invention, in the first step, a flow rate setting value given to a flow rate regulator interposed in a dilution gas supply line and a flow rate regulator interposed in a process gas supply line Is always related to the flow rate set value to be maintained at a constant value.

  According to such a configuration, the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line so that the process gas concentration in the process chamber becomes each of a plurality of known concentrations. When a predetermined flow rate set value change is applied to the above, since the sum of the supply amount of the dilution gas and the supply amount of the process gas is always maintained constant, there is an advantage that the pressure fluctuation hardly occurs in the process chamber.

  In a preferred embodiment of the present invention, in the second step, a flow rate setting value given to a flow rate regulator interposed in a dilution gas supply line and a flow rate regulator interposed in a process gas supply line Is always related to the flow rate set value to be maintained at a constant value.

  According to such a configuration, the dilution gas or the process gas supply amount in the process chamber is interposed in the dilution gas supply line and / or the process gas supply line so as to change in a pulse waveform. When the predetermined flow rate setting value change is applied to the flow rate regulator, the sum of the supply amount of the dilution gas and the supply amount of the process gas is always kept constant, so that it is difficult for pressure fluctuation to occur in the process chamber. There are advantages.

  In a preferred embodiment of the present invention, in the second step, the supply waveform drawn when the supply amount of the dilution gas or the process gas in the process chamber changes is an impulse waveform, whereby the acquired plasma emission A pulse response is generated directly based on the change in intensity.

  According to such a configuration, if the plasma emission intensity can be detected with high sensitivity, a pulse response is directly generated based on the obtained change in the plasma emission intensity, so that post-processing is facilitated.

  In another preferred embodiment of the present invention, in the second step, the supply waveform drawn when the supply amount of the dilution gas or the process gas in the process chamber changes is a step waveform, and thus acquired. A pulse response is generated by taking a difference by shifting the change in plasma emission intensity with time.

  According to such a configuration, even when the plasma emission intensity cannot be detected with high sensitivity, a sufficient amount of supply amount change can be obtained. Therefore, based on the approximate curve, mathematical expressions such as time axis shift and difference are obtained. The target pulse response waveform is accurately generated by the processing.

  In a preferred embodiment of the present invention, the emission intensity detecting means is a spectrometer capable of detecting the emission intensity for each of a plurality of wavelengths.

  According to such a configuration, there is an advantage that the plasma emission intensities of various gas types existing in the process chamber can be individually detected.

  From another aspect, the present invention can be grasped as a process gas concentration control device in a plasma reactor processing system.

  This apparatus is premised on a plasma reactor processing system having a certain configuration. This plasma reactor processing system includes a process chamber having a built-in plasma generation unit, a dilution gas supply line connecting the dilution gas supply source and the process chamber, and a process gas connecting the process gas supply source and the process chamber. And a gas exhaust pipe for connecting the process chamber and the vacuum pump.

  In each of the dilution gas supply line and the process gas supply line, the opening of the flow rate adjustment valve is automatically changed in a direction in which the deviation between the given flow rate setting value and the flow rate detection value decreases. The flow regulator which has the function to perform is interposed.

  In addition, a pressure controller having a function of automatically changing the opening degree of the flow control valve in a direction in which the deviation between the pressure setting value and the pressure measurement value decreases is interposed in the exhaust pipe for the gas in the chamber. Yes. In addition, the plasma reactor processing system is provided with emission intensity detection means for detecting the plasma emission intensity of the dilution gas or process gas in the process chamber.

  On the premise of the presence of such a plasma reactor processing stem, the apparatus of the present invention is provided with five means including first to fifth.

  The first means is that while the gas pressure in the process chamber is maintained the same as the gas pressure in the assumed plasma process, the process gas concentration in the process chamber is changed to each of a plurality of known concentrations. A plurality of known process gas concentration states obtained in such a manner that a predetermined flow rate setpoint change is given to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line A calibration curve indicating the relationship between the known process gas concentration and the plasma emission intensity of the dilution gas or process gas at that concentration is obtained by obtaining the emission intensity of the dilution gas or process gas in each of the above through the emission intensity detection means. create.

  The second means is that the supply pressure of the dilution gas or the process gas in the process chamber is a predetermined waveform while the gas pressure in the process chamber is maintained the same as the gas pressure in the assumed plasma process. And a predetermined flow rate set value change is given to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line, and the dilution gas supply amount obtained in this way Alternatively, a change in plasma emission intensity in response to a change in the process gas supply amount is obtained via the emission intensity detection means, and this is converted into a concentration based on the calibration curve created by the first means, thereby diluting. Generates a pulse response characteristic that shows the relationship between the pulsed change in the gas supply rate or process gas supply rate and the resulting pulse response of dilution gas concentration or process gas concentration .

  According to the third means, based on the pulse response characteristic acquired by the second means and the flow rate setting value application interval determined by the setting characteristic of each flow rate regulator, the flow rate setting value change to be given to each flow rate setter. A model that defines the relationship between the time-division instantaneous value and the time-division instantaneous value of the process gas concentration change in the process chamber is created.

  The fourth means is the time-division instantaneous value of the flow set value change to be given to each flow setter and the change in the process gas concentration in the process chamber defined using the model created in the third means. By substituting the time-division instantaneous value of the desired process gas concentration change into the function matrix that defines the relationship with the time-division instantaneous value, the time-division instantaneous value of the optimum flow set value change to be given to each flow setter is obtained. get.

  The fifth means uses the time-division instantaneous value of the optimum flow rate set value change obtained by the fourth means for the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line. By providing, the process gas concentration in the process chamber is controlled to obtain a desired process gas concentration change.

  According to such a configuration, in the plasma reactor processing system having specific equipment specifications, the process gas concentration in the process chamber is set to a desired concentration profile under the restriction of the upper limit value of the supplied supply gas flow rate. It becomes possible to control precisely.

  In a preferred embodiment of the present invention, in the first means, the flow rate set value given to the flow rate regulator interposed in the dilution gas supply line and the flow rate regulator interposed in the process gas supply line Is always related to the flow rate set value to be maintained at a constant value.

  According to such a configuration, the flow rate adjustment interposed in the dilution gas supply line and / or the process gas supply line so that the process gas concentration in the process chamber becomes each of a plurality of known concentrations. When a predetermined flow rate setting value change is given to the apparatus, the supply amount of the dilution gas and the supply amount of the process gas are always maintained constant, and therefore, there is an advantage that pressure fluctuation hardly occurs in the process chamber.

  In a preferred embodiment of the present invention, in the second means, a flow rate set value given to a flow rate regulator interposed in the dilution gas supply line and a flow rate set value interposed in the process gas supply line Is always related to the flow rate set value to be maintained at a constant value.

  According to such a configuration, in the second means, the dilution gas supply line and / or the process gas flow rate is changed so that the supply amount of the dilution gas or the process gas in the process chamber changes while drawing a pulse waveform. When a predetermined flow rate setting value change is given to the flow rate regulator interposed in the supply line, the sum of the dilution gas supply amount and the process gas supply amount is always kept constant. There is an advantage that pressure fluctuation hardly occurs.

  In a preferred embodiment of the present invention, in the second means, the supply amount waveform drawn when the supply amount of the dilution gas or process gas in the process chamber changes is an impulse waveform, whereby the acquired plasma emission A pulse response is generated directly based on the change in intensity.

  According to such a configuration, if the plasma emission intensity can be detected with high sensitivity, a pulse response is directly generated based on the obtained change in the plasma emission intensity, so that post-processing is facilitated.

  In another preferred embodiment of the present invention, in the second means, the supply waveform drawn when the supply amount of the dilution gas or the process gas in the process chamber changes is a step waveform, and is thus acquired. A pulse response is generated by taking a difference by shifting the change in plasma emission intensity with time.

  According to such a configuration, even when the plasma emission intensity cannot be detected with high sensitivity, a sufficient amount of supply amount change can be obtained. Therefore, based on the approximate curve, mathematical expressions such as time axis shift and difference are obtained. The target pulse response waveform is accurately generated by the processing.

  In a preferred embodiment of the present invention, the emission intensity detecting means is a spectrometer capable of detecting the emission intensity for each of a plurality of wavelengths.

  According to such a configuration, the emission intensity can be individually detected for each of various gas types included in the process chamber.

  Further, in a preferred embodiment of the present invention, the first means, the second means, the third means, the fourth means, and the PLC incorporating a user program functioning as the fifth means are configured. You may do it.

  According to the present invention, in a plasma reactor processing system having specific equipment specifications, the process gas concentration in the process chamber is accurately measured with a desired concentration profile under the restriction of the upper limit value of a given supply gas flow rate. It becomes possible to control.

  Hereinafter, a preferred embodiment of a process gas concentration control method and apparatus in a plasma reactor processing system according to the present invention will be described in detail with reference to the accompanying drawings.

As described above, this type of plasma reactor processing system generally has a process chamber containing a plasma generator (for example, a parallel plate electrode type, a microwave antenna type, etc.) and one or more types. Dilution gas sources (for example, Ar, Kr, Xe, etc.) and a process gas chamber, and one or more process gas sources (for example, H ₂ , O ₂ , NF) ₃ , Cl ₂ , SiCl ₄ , HBr, SF ₆ , C ₅ F ₈ , CF _4, etc.) and a process gas supply line connecting the process chamber, a process chamber and a vacuum pump (such as a turbo molecular pump) In the configuration diagram of the entire plasma reactor processing system shown in FIG. 1, the piping system is simplified for convenience of explanation. To Note that only the piping system of the HBr which is one of Ar and process gas which is one of the dilution gas is shown.

  As shown in the figure, this plasma reactor processing system includes a process chamber 1 containing plasma generators 11 and 12, a dilution gas supply pipe connecting a supply source of Ar as a dilution gas and the process chamber 1. A dilution gas supply line 22 connecting the path 21, a supply source of HBr, which is a process gas, and the process chamber 1, and a gas exhaust line 33 connecting the process chamber 1 and the turbo molecular pump (TMP) 31. And have.

  A manual valve 21a, a flow control system (FCS) 21b, and an electromagnetic valve 21c are interposed in the dilution gas supply pipe 21 in this order. In addition, a manual valve 22a, a flow control system (FCS) 22b, and an electromagnetic valve 22c are sequentially interposed in the process gas supply line 22. In the illustrated example, the dilution gas supply pipe 21 and the process gas supply pipe 22 are joined together, and then connected to the process chamber 1 via the junction pipe 23.

  Here, the flow control system (FCS) 21b, 22b has a flow rate adjusting valve in a direction in which a deviation between a given flow rate set value and a flow rate detection value corresponding to the gas pressure measured through the pressure measuring unit decreases. A pressure control type flow rate regulator having a function of automatically changing the opening degree of the valve is configured.

  On the other hand, an auto-pressure controller (APC) 32 is interposed in the chamber gas discharge pipe 33. The response pressure controller (APC) 32 constitutes a pressure controller having a function of automatically changing the opening degree of the flow control valve in a direction in which the deviation between the pressure set value and the pressure measurement value decreases. .

  Further, in connection with the present invention, the plasma reactor processing system is newly provided with a spectroscope 42 that functions as emission intensity detection means for detecting the plasma emission intensity of the dilution gas or process gas in the process chamber 1. .

  In addition, in the figure, 13 is a microwave power source, 14 is a magnetron, 15 is an isolator, 16 is a tuner, 17 is an RF power source, and 41 is a pressure detector for detecting gas pressure in the process chamber 1.

  The control devices and sensors described above are connected to the PLC 51 via predetermined signal lines, and various data generated by the PLC 51 can be displayed on the screen of the programmable terminal (PT) 52 connected to the PLC 51. Yes.

  The PLC 51 incorporates a user program that functions as five control means including first to fifth means in order to realize a five-step control step including first to fifth steps described later. It is. Then, the PLC 51 executes these user programs, thereby realizing process gas concentration control described later.

  A general flowchart showing the processing of the PLC implementing the method of the present invention is shown in FIG. As shown in the figure, the PLC processing for carrying out the method of the present invention includes calibration curve creation processing (step 101), transient response characteristic acquisition processing (step 102), model creation processing (step 103), and optimum It consists of a gas supply condition acquisition process (step 104) and an optimum gas supply condition execution process (step 105).

  The details of the calibration curve creation process are shown in FIG. In this calibration curve creation process, the process gas concentration in the process chamber 1 (in this example, HBr) is maintained while the gas pressure in the process chamber 1 is kept the same as the gas pressure in the assumed plasma process. The flow control system is interposed in the supply line 21 for the dilution gas (Ar in this example) and the supply line 22 for the process gas (HBr in this example) so that the concentration becomes a plurality of known concentrations. (FCS) 21 b and 22 b are given a predetermined flow rate value change, and the emission intensity of the dilution gas or process gas (dilution gas in this example) in each of a plurality of known in-chamber process gas concentration states thus obtained is set. Acquired through the spectroscope 42 to obtain a known process gas concentration and dilution gas or process at that concentration Scan (in this example a dilution gas) to a calibration curve showing the relationship between the plasma emission intensity of.

  Specifically, as shown in FIG. 3, first, in the initialization process (step 201), A1 (Ar flow rate) is set to “420”, K2 (HBr flow rate) is set to “0”, and ΔK (flow rate change width). Is set to “20”.

  Subsequently, after the timing start process (step 202) is executed, a predetermined sample start time t1 (15 seconds in this example) is waited for (step 203 YES), and the Ar emission intensity sample (every Δt) is obtained. Repeat (step 204), wait for a predetermined sample end time t2 (25 seconds in this example) to elapse (YES in step 205), stop the Ar emission intensity sample, average the sample value, and process gas of 1 The sample value corresponding to the concentration (concentration 0%) is determined (step 206), and after waiting for the time t3 (30 seconds in this example) to elapse (YES in step 207), the process gas known concentration (concentration 0) is determined. %) Is completed (steps 202 to 207).

  Thereafter, the value of the flow rate change width ΔK is updated by “+20” (step 208), and the FCS setting process (step 212) corresponding to the known concentration (concentration 0.048) of the next process is executed. The process (steps 202 to 207) is repeatedly executed, and after waiting for ΔK> “120” (YES in step 209), the process proceeds to the interpolation process (step 210).

  In this interpolation process (step 210), Ar emission intensity sample values obtained discretely corresponding to each known density (0.0, 0.048, 0.095... 0.286) Interpolate using the least squares method.

  Thereafter, the emission intensity thus obtained is stored in the PLC memory in correspondence with each concentration, thereby completing a concentration / emission intensity table corresponding to the calibration curve.

  FIG. 4 shows a chart showing the relationship between each known concentration and the HBr / Ar flow rate in the FCS setting process (step 212) among the processes described above. As is apparent from the figure, the flow rate setting values (420, 400, 380... 300) given to the FCS 21b interposed in the dilution gas (Ar) supply pipe 21 and the process gas (HBr) supply pipe. The flow rate set value (0, 20, 40... 120) given to the FCS 22b interposed in the path 22 is always related so that the sum of both is maintained at a constant value (420). I understand. Therefore, although the gas concentration increases in units of 0.048, the total amount of gas supplied into the process chamber 1 is always maintained constant, so that pressure fluctuations associated with changes in the process gas concentration are suppressed as much as possible. The

  A graph showing the sample time zone of the emission intensity in the series of processes described above is shown in FIG. As shown in the figure, when the emission intensity is sampled by changing from a known concentration to another known concentration, waiting for the arrival of a time zone (t1 to t2) in which the concentration after the change is set, Since the samples are taken at every Δt, the plurality of sample values obtained in this way are relatively stable values, and after averaging these, the emission intensity corresponding to the known concentration is determined, so measurement is performed. Errors can be avoided as much as possible.

  FIG. 6 is a screen explanatory diagram showing a display example of a calibration curve drawn on the display screen of PT52 based on the density / luminescence intensity table created in step 211. As shown in the figure, according to this calibration curve, the relationship between the gas concentration and the emission intensity can be clearly understood. Therefore, by using this calibration curve, the concentration of the process gas (HBr) in the process chamber 1 can be specified based on the emission intensity obtained from the spectroscope 42.

  FIG. 7 shows a display example of a graph showing a change in light emission intensity when the gas concentration is sharply changed from 0.0 to 0.238. As shown in the figure, it is understood that there is a clear correlation between the gas concentration and the emission intensity.

  Next, FIG. 8 shows details of the transient response characteristic acquisition process (part 1). In this transient response characteristic acquisition process, the dilution gas (Ar in this example) in the process chamber 1 is maintained while the gas pressure in the process chamber 1 is kept the same as the gas pressure in the assumed plasma process. Alternatively, the FCS 21b interposed in the dilution gas (Ar) supply line 21 and the process gas (HBr) supply line 22 so that the supply amount of the process gas (HBr in this example) changes in an impulse waveform. , 22b is given a predetermined flow rate set value change, and a change in plasma emission intensity in response to a pulse-like change in the dilution gas supply amount or process gas supply amount obtained in this way is obtained via the spectroscope 41, and this Is converted to a concentration based on the calibration curve created in the first step, so that the dilution gas supply amount or the process gas supply amount can be reduced. Obtaining a pulse response characteristics showing the relationship between the pulse response of the focal change the diluent gas concentration or the process gas concentration involved.

  That is, when the processing is started in FIG. 8, first, the flow rate value is set for the FCSs 21b and 22b with K1 (Ar flow rate) set to “420” and K2 (HBr flow rate) set to “0”, so that the gas concentration becomes 0. Setting to 0 is performed (step 301).

  Subsequently, a delay process for “flow rate set value application interval” (200 msec in this example) determined by the actual product characteristics (response performance) of the FCSs 21b and 22b is executed (step 302).

  Thereafter, by setting K1 (Ar flow rate) to “320” and K2 (HBr flow rate) to “100”, the gas concentration is set to 0.238 (pulse rising) (step 303).

  Subsequently, after the timing process is started (step 304), the Ar emission intensity sample (every Δt) is repeatedly performed (step 305) until the pulse fall time comes (step 306 NO). Thereby, the density | concentration of HBr is measured indirectly.

  In this state, if the pulse fall time has arrived (step 306 YES), K1 (HBr flow rate) is set to “0”, K2 (Ar flow rate) is set to “420”, and the gas concentration is set to 0.0 (pulse fall). Is set (step 307).

  Thereafter, the Ar emission intensity sample (every Δt) is repeated (step 308) until a predetermined sample end time arrives (step 309 YES). Thus, the gas concentration is indirectly measured.

  By performing the series of processes (steps 301 to 309) as described above, transient response characteristics in the process chamber are acquired using the HBr gas. Here, a conceptual diagram for explaining the transient response characteristic is shown in FIG. As shown in FIG. 11A, the 0.0 density setting process (step 301), the pulse rise process (step 303), and the pulse fall process (step 307) described above are performed. An input pulse waveform is generated.

  Further, the Ar emission intensity sample process (step 305) and the Ar emission intensity sample process (step 308) are executed, whereby the waveform of the pulse response wave shown in FIG. 11B is acquired.

  Next, details of the transient response characteristic acquisition process (part 2) are shown in FIG. In this transient response characteristic acquisition process, the dilution gas (Ar in this example) in the process chamber 1 is maintained while the gas pressure in the process chamber 1 is kept the same as the gas pressure in the assumed plasma process. Alternatively, the FCS 21b interposed in the dilution gas (Ar) supply line 21 and the process gas (HBr) supply line 22 so that the supply amount of the process gas (HBr in this example) changes in a step waveform. , 22b is given a predetermined flow rate set value change, and a change in plasma emission intensity in response to a pulse-like change in the dilution gas supply amount or process gas supply amount obtained in this way is obtained via the spectroscope 41, and this Is converted into a concentration based on the calibration curve created in the first step described above, so that the pulse of the dilution gas supply amount or the process gas supply amount is Jo change and acquires the pulse response characteristics showing the relationship between the pulse response of the diluent gas concentration or the process gas concentration involved.

  That is, when the processing is started in FIG. 8, first, the flow rate value is set for the FCSs 21b and 22b with K1 (Ar flow rate) set to “420” and K2 (HBr flow rate) set to “0”, so that the gas concentration becomes 0. Setting to 0 is performed (step 401).

  Subsequently, a delay process for “flow rate set value application interval” (200 msec in this example) determined by the actual product characteristics (response performance) of the FCS 21b and 22b is executed (step 402).

  Thereafter, by setting K1 (Ar flow rate) to “320” and K2 (HBr flow rate) to “100”, the gas concentration is set to 0.238 (pulse rising) (step 403).

  Subsequently, after the timing process is started (step 404), the Ar emission intensity sample (every Δt) is repeatedly performed (step 405) until the sample end time arrives (step 406 NO). Thereby, the density | concentration of HBr is measured indirectly.

  A step waveform IN1 which is a flow rate waveform in the above-described processing is shown in FIG. 10A, and a concentration waveform OUT1 which is an output waveform is shown in FIG. 10B. Note that it is preferable to perform waveform shaping by performing appropriate approximation processing when the fluctuation component of the concentration waveform OUT1 is large due to the performance of the spectroscope which is a light emission intensity detector.

  Subsequently, the data group on the memory corresponding to the flow waveform IN1 and the concentration waveform OUT1 is shifted by 200 msec from time t1 to t2 in the time axis direction, thereby corresponding to the shifted flow waveform IN2 and concentration waveform OUT2. A data group is obtained (step 407). FIG. 10C shows the flow waveform IN2 after the shift obtained in this way, and FIG. 10D shows the concentration waveform OUT2 after the shift.

  Subsequently, by calculating a difference (IN1-IN2) between the step waveform IN1 before the shift and the step waveform IN2 after the shift, the input impulse waveform IN3 is generated, and the concentration waveform OUT1 before the shift and the after the shift An impulse response waveform OUT3 is generated by obtaining a difference (OUT1-OUT2) from the concentration waveform OUT2. The impulse waveform IN3 thus obtained is shown in FIG. 10 (e), and the impulse response waveform OUT3 is shown in FIG. 10 (f).

  A screen explanatory diagram of a display example of the pulse response wave acquired in this way is shown in FIG. As shown in the figure, it will be understood that by executing the transient response characteristic acquisition process shown in FIG. 8 or FIG. 9, the pulse response wave corresponding to the actual controlled object model can be accurately obtained. .

  Next, in the model creation process (step 103), as shown in FIG. 13, the flow rate setting value application interval determined by the pulse response characteristics acquired in the transient response characteristics acquisition process (step 102) and the product characteristics of each FCS. Based on (t1, t2,..., T150), the time division instantaneous value (c1, c2,... C150) of the flow rate set value change to be given to the FCS 22b and the time division instantaneous of the process gas concentration change in the process chamber A model that defines the relationship with the values (b1, b2,..., B150) is created. Here, A1 to A150 indicate gas concentrations (values on the Y axis in FIG. 12) at time t1 to t150 of the pulse response waveform.

  In the subsequent optimum gas supply condition acquisition process (step 104), each flow rate setter defined using the model created in the model creation process (step 103) in order to realize so-called “model prediction control”. Defines the relationship between the time-division instantaneous value (c1, c2... C150) of the flow rate setting value change to be given to the time-division and the time-division instantaneous value (b1, b2. By substituting the time-division instantaneous values (c1, c2,... C150) of the desired process gas concentration change into the function determinant (see FIG. 11), the optimum flow rate setting value change to be given to each flow rate setting device Time-division instantaneous values (b1, b2,..., B150) are acquired. This type of “model predictive control” is disclosed in various documents (for example, the text “model predictive control” for beginners, Kyoto University Graduate School of Engineering, Manabu Kano, published in January 1997). Therefore, detailed description is omitted.

  FIG. 14 is an explanatory diagram showing two examples of target density profiles. As shown in the figure, in this type of plasma processing system, even if the target process gas concentration after the settling is the same due to demands such as the characteristics of manufactured products and process gas usage efficiency, If you want to raise the process gas concentration from 0.0 to the target concentration as soon as possible under the restriction of the upper limit value of the gas flow rate (Case 1) and constant under the restriction of the upper limit value of the supply gas flow rate There is a demand (Case 2) for gradually increasing the process gas concentration from the 0.0 concentration to the target concentration with the elapse time. In FIG. 12, (Case 1) is represented by reference numeral P1, and (Case 2) is represented by reference numeral P2.

  Therefore, in the above-described optimum gas supply condition acquisition process (step 104), the gas concentration time-division instantaneous values on the line indicated by the symbol P1 are converted into the time-division instantaneous values (b1, b2,... On the output side shown in FIG. b150), and in the case of (case 2) indicated by symbol P2, the time-division instantaneous value on the straight line indicated by symbol P2 is converted into the time-division instantaneous value (b1, b2,... shown in FIG. By substituting each into b150), the value of the time-division instantaneous value (c1, c2,... C150) corresponding to the optimum supply amount can be obtained.

  FIG. 15 shows the relationship between the optimum gas supply conditions thus obtained and the optimum rise of gas concentration. By substituting the output (b1, b2,..., B150) corresponding to the optimum rising of the gas concentration shown in FIG. 5B into the above determinant, the optimum gas supply condition shown in FIG. The input (b1, b2,..., B150) corresponding to can be acquired.

  In the subsequent optimum gas supply condition execution process (step 105), the flow rate setting values generated based on the values of the inputs (b1, b2,..., B150) thus obtained are used as the dilution gas supply line and process. By supplying the FCS 21b and 22b interposed in the gas supply pipes, the process gas concentration in the process chamber 1 is controlled to a desired value.

  FIG. 16 shows a screen explanatory diagram of a graph showing the density control result by comparing the theoretical value with the experimental value. As shown in the figure, it is understood that the experimental value indicated by the solid line in the figure well follows the theoretical value indicated by the broken line in the figure.

  As is clear from the above description of the embodiment, according to the present invention, since the calibration curve and the pulse response are obtained using the actual plasma reactor processing system itself to be controlled, the concentration thus obtained is obtained. The control result is based on the FCS capability built into the system. Therefore, by setting the output value arbitrarily in the determinant shown in Fig. 13, it is possible to acquire the input that can be actually operated. In this way, optimal density control can be realized.

  According to the present invention, in a plasma reactor processing system having a specific equipment specification, the process gas concentration in the process chamber is precisely measured with a desired concentration profile under the restriction of the upper limit value of the flow rate of a given supply gas. It becomes possible to control to.

It is a block diagram of the whole system of a plasma reactor processing system. It is a general flowchart which shows the process of PLC which implements the method of this invention. It is a flowchart which shows the detail of a calibration curve creation process. It is a graph which shows the relationship between gas concentration and a HBr / Ar flow volume. It is a graph which shows the sample time slot | zone of emitted light intensity. It is screen explanatory drawing which shows the example of a display of a calibration curve. It is a display example of the graph which shows the change of the emitted light intensity when changing Ar gas concentration from 0% to 100% sharply. It is a flowchart which shows the detail of the transient response characteristic acquisition process (the 1). It is a flowchart which shows the detail of the transient response characteristic acquisition process (the 1). It is each waveform figure which leads to transient response characteristic acquisition. It is a conceptual diagram explaining a transient response characteristic. It is screen explanatory drawing which shows the example of a display of a pulse response wave. It is explanatory drawing which shows the model which prescribes | regulates the relationship between flow volume input and density | concentration output. It is explanatory drawing which shows two examples of a target density profile. It is explanatory drawing of the process for acquiring optimal gas supply conditions. It is screen explanatory drawing of the graph which compares and shows a density | concentration control result with a theoretical value and an experimental value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Process chamber 11,12 Plasma generation part 13 Microwave power supply 14 Magnetron 15 Isolator 16 Tuner 17 RF power supply 21 Supply line of dilution gas 21a Manual valve 21b FCS
21c Solenoid valve 22 Process gas supply line 22a Manual valve 22b FCS
22c Solenoid valve 23 Junction line 31 Turbo molecular pump (TMP)
32 Response pressure controller (APC)
33 Arrangement pipeline 41 Pressure detector 42 Spectrometer 51 PLC
52 PT

Claims (13)

A process chamber containing a plasma generator;
A dilution gas supply line connecting the dilution gas supply source and the process chamber;
A process gas supply line connecting the process gas supply source and the process chamber;
A gas exhaust line for connecting the process chamber and the vacuum pump;
A function for automatically changing the opening of the flow rate adjusting valve in the direction in which the deviation between the given flow rate setting value and the flow rate detection value decreases in each of the dilution gas supply line and the process gas supply line A flow rate regulator having a flow rate control valve is interposed, and a function for automatically changing the opening of the flow rate control valve in the direction in which the deviation between the pressure setting value and the pressure measurement value decreases is provided in the gas exhaust line in the chamber. A method for controlling a process gas concentration in a plasma reactor processing system, wherein a pressure controller is interposed,
The plasma reactor processing system includes:
Including emission intensity detection means for detecting the plasma emission intensity of the dilution gas or process gas in the process chamber, and the method comprises:
The dilution gas so that the process gas concentration in the process chamber is each of a plurality of known concentrations while the gas pressure in the process chamber remains the same as the gas pressure in the assumed plasma process. A predetermined flow rate setpoint change with respect to the flow rate regulator interposed in the process gas supply line and / or the process gas supply line, and the dilution gas in each of the plurality of known process gas concentration states thus obtained, or A first step of creating a calibration curve indicating the relationship between the known process gas concentration and the plasma emission intensity of the dilution gas or process gas at that concentration by obtaining the emission intensity of the process gas via the emission intensity detecting means. When,
The supply pressure of the dilution gas or the process gas in the process chamber changes so as to draw a predetermined waveform while the gas pressure in the process chamber is maintained to be the same as the gas pressure in the assumed plasma process. In addition, a predetermined flow rate setting value change is applied to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line, and the dilution gas supply amount or process gas supply amount thus obtained is changed. A change in plasma emission intensity in response to the change is acquired via the emission intensity detecting means, and converted into a concentration based on the calibration curve created in the first step, whereby a dilution gas supply amount or a process gas is obtained. A pulse response characteristic is generated that indicates the relationship between the pulse-like change in the supply amount and the pulse response of the dilution gas concentration or process gas concentration associated therewith. And the step of,
Based on the pulse response characteristics acquired in the second step and the flow rate setting value application interval determined by the product characteristics of each flow rate setting device, the time-division instantaneous value and process of the flow rate setting value change to be given to each flow rate setting device A third step of creating a model that defines a relationship between time-division instantaneous values of process gas concentration changes in the chamber;
The time-division instantaneous value of the flow set value change to be given to each flow setter and the time-division instantaneous value of the process gas concentration change in the process chamber, which are defined using the model created in the third step. A time division instantaneous value of the optimum flow rate setting value change to be given to each flow rate setting device is obtained by substituting a time division instantaneous value of a desired process gas concentration change into a function determinant that defines the relationship. Steps,
By providing the time-division instantaneous value of the optimum flow rate setting value change obtained in the fourth step to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line, And a fifth step of controlling the process gas concentration in the chamber so as to obtain a desired change in the process gas concentration, and a method for controlling the process gas concentration in the plasma reactor processing system.   In the first step, the flow rate setting value given to the flow rate regulator interposed in the dilution gas supply line and the flow rate setting value given to the flow rate regulator interposed in the process gas supply line are always The process gas concentration control method in the plasma reactor processing system according to claim 1, wherein the sum of the two is related to be maintained at a constant value.   In the second step, the flow rate setting value given to the flow rate regulator interposed in the dilution gas supply line and the flow rate setting value given to the flow rate regulator interposed in the process gas supply line are always The process gas concentration control method in the plasma reactor processing system according to claim 1, wherein the sum of the two is related to be maintained at a constant value.   In the second step, the supply waveform drawn when the supply amount of the dilution gas or process gas in the process chamber changes is an impulse waveform, so that the pulse is directly pulsed based on the obtained change in plasma emission intensity. The method for controlling process gas concentration in a plasma reactor processing system according to claim 1, wherein a response is generated.   In the second step, the supply amount waveform drawn when the supply amount of the dilution gas or the process gas in the process chamber changes is a step waveform, whereby the change in the acquired plasma emission intensity is shifted by the time axis and the difference is obtained. The method for controlling the process gas concentration in the plasma reactor processing system according to claim 1, wherein a pulse response is generated by taking   2. The method of controlling a process gas concentration in a plasma reactor processing system according to claim 1, wherein the emission intensity detecting means is a spectrometer capable of detecting the emission intensity for each of a plurality of wavelengths. A process chamber containing a plasma generator;
A dilution gas supply line connecting the dilution gas supply source and the process chamber;
A process gas supply line connecting the process gas supply source and the process chamber;
A gas exhaust line for connecting the process chamber and the vacuum pump;
A function for automatically changing the opening of the flow rate adjusting valve in the direction in which the deviation between the given flow rate setting value and the flow rate detection value decreases in each of the dilution gas supply line and the process gas supply line A flow rate regulator having a flow rate control valve is interposed, and a function for automatically changing the opening of the flow rate control valve in the direction in which the deviation between the pressure setting value and the pressure measurement value decreases is provided in the gas exhaust line in the chamber. An apparatus for controlling a process gas concentration in a plasma reactor processing system, in which a pressure controller is interposed,
The plasma reactor processing system includes:
Including emission intensity detection means for detecting the plasma emission intensity of the dilution gas or process gas in the process chamber, and the apparatus comprises:
The dilution gas so that the process gas concentration in the process chamber is each of a plurality of known concentrations while the gas pressure in the process chamber remains the same as the gas pressure in the assumed plasma process. A predetermined flow rate setpoint change to the flow rate regulator interposed in the process gas supply line and / or the process gas supply line, and the dilution gas in each of the plurality of known process gas concentration states thus obtained, or First means for obtaining a calibration curve indicating the relationship between the known process gas concentration and the plasma emission intensity of the dilution gas or process gas at the concentration by obtaining the emission intensity of the process gas via the emission intensity detecting means When,
The supply pressure of the dilution gas or the process gas in the process chamber changes so as to draw a predetermined waveform while the gas pressure in the process chamber is maintained to be the same as the gas pressure in the assumed plasma process. In addition, a predetermined flow rate setting value change is applied to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line, and the dilution gas supply amount or process gas supply amount thus obtained is changed. A change in plasma emission intensity in response to the change is acquired via the emission intensity detecting means, and converted into a concentration based on the calibration curve created in the first step, whereby a dilution gas supply amount or a process gas is obtained. A pulse response characteristic is generated that indicates the relationship between the pulse-like change in the supply amount and the pulse response of the dilution gas concentration or process gas concentration associated therewith. And the means of,
Based on the pulse response characteristic acquired by the second means and the flow rate setting value application interval determined by the product characteristics of each flow rate setting device, the time-division instantaneous value and process of the flow rate setting value change to be given to each flow rate setting device A third means for creating a model for defining a relationship with a time-division instantaneous value of a process gas concentration change in the chamber;
The time-division instantaneous value of the flow set value change to be given to each flow setter and the time-division instantaneous value of the process gas concentration change in the process chamber, defined using the model created by the third means, A time division instantaneous value of the optimum flow rate setting value change to be given to each flow rate setting device is obtained by substituting a time division instantaneous value of a desired process gas concentration change into a function determinant that defines the relationship. Means,
By giving the time-division instantaneous value of the optimum flow rate setting value change obtained by the fourth means to the flow rate regulator interposed in the dilution gas supply line and / or the process gas supply line, And a fifth means for controlling the process gas concentration in the chamber so that a desired change in the process gas concentration can be obtained.   In the first means, the flow rate set value given to the flow rate regulator interposed in the dilution gas supply line and the flow rate set value given to the flow rate regulator interposed in the process gas supply line are always 8. The apparatus for controlling a process gas concentration in a plasma reactor processing system according to claim 7, wherein the sum of the two is related to be maintained at a constant value.   In the second means, the flow rate setting value given to the flow rate regulator interposed in the dilution gas supply line and the flow rate setting value given to the flow rate regulator interposed in the process gas supply line are always The method of controlling a process gas concentration in a plasma reactor processing system according to claim 7, wherein the sum of the two is related to be maintained at a constant value.   In the second means, the supply amount waveform drawn when the supply amount of the dilution gas or the process gas in the process chamber changes is an impulse waveform, whereby the pulse is directly pulsed based on the obtained change in the plasma emission intensity. 8. The method of controlling a process gas concentration in a plasma reactor processing system according to claim 7, wherein a response is generated.   In the second means, the supply amount waveform drawn when the supply amount of the dilution gas or the process gas in the process chamber changes is a step waveform, whereby the change in the acquired plasma emission intensity is shifted by the time axis and the difference is obtained. The method for controlling the process gas concentration in the plasma reactor processing system according to claim 7, wherein a pulse response is generated by taking   The apparatus for controlling a process gas concentration in a plasma reactor processing system according to claim 7, wherein the emission intensity detecting means is a spectrometer capable of detecting the emission intensity for each of a plurality of wavelengths.   8. It is comprised by PLC in which the user program which functions as 1st means, 2nd means, 3rd means, 4th means, and 5th means was incorporated. An apparatus for controlling a process gas concentration in the plasma reactor processing system described.

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