JP2006054148A - Plasma treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device capable of detecting fluctuation of its treatment characteristics and restraining the fluctuation. <P>SOLUTION: The plasma treatment device provided with a reaction vessel 1 with its inner side wall insulated, a sample stand 5 arranged in the reaction vessel, and an antenna 10, applying plasma treatment on a sample loaded on the sample stand by supplying high-frequency power to the antenna from a plasma-generating power source and plasmolyzing treatment gas introduced in the reaction vessel, is further provided with a matching unit 11 for taking impedance matching between the plasma-generating power source and a load circuit including the antenna. The matching unit, provided with a sensor for measuring impedance characteristics of the load circuit side, changes a matching attainment point and a matching operation locus reaching the matching attainment point as the load side is seen from an input end of the matching unit in accordance with a measurement value of the sensor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus, and more particularly to a technique for suppressing fluctuations in processing characteristics of a plasma processing apparatus.

  With the miniaturization of devices, high integration, and diversification of constituent materials, plasma processing equipment used for semiconductor manufacturing not only improves processing accuracy, but also stabilizes long-term processing characteristics in the same equipment, The importance of mass productivity, such as the suppression of differences in processing characteristics, is being emphasized.

  For example, in a plasma etching apparatus, when processing is repeated, deposits accumulate on the inner wall of the reaction chamber or the inner wall is worn. With such deposition and wear, the wafer processing characteristics continue to change over a long period of time, and the performance of the manufactured device satisfies the standard value, deviating from the standard of allowable processing characteristics fluctuation of fine pattern processing. No longer. Further, when the deposit is peeled off, minute foreign matter is generated. In addition, wear of parts constituting the processing chamber induces abnormal discharge and the like, causing a device failure.

  For this reason, in recent plasma processing apparatuses, whether or not production can be continued is continuously monitored by monitoring many parameters (emission spectrum, bias waveform peak-to-peak voltage Vpp, reflected wave behavior, etc.) that are considered to be related to the processing state. Measures such as judging, utilizing a process such as plasma cleaning to reduce deposits, or utilizing a new inner wall material to prevent wear are being studied. As a result, it is possible to stop the processing before the occurrence of a product defect or to lengthen the time required until the defect occurs.

  However, in the future, the criteria for variation in allowable processing characteristics of fine pattern processing will become stricter (for example, in a 45 nm node, the gate length is on the order of 20 nm and variations of 2 nm or more are not allowed). For this reason, even if the mass production status is continuously monitored based on various parameters of the apparatus, the processing characteristics slightly change, and the allowable standard is deviated.

  In such a case, it is necessary to perform a sweeping operation of the reaction chamber or a replacement operation of consumable parts, shortening the cycle of the cleaning operation and increasing the frequency of replacement of the consumable parts. As a result, the operating rate is reduced and the cost of consumable parts is increased. Si-based, C-based, and Al-based deposit removal methods using plasma cleaning are also used, but only those that are to be removed are completely removed, leaving no excess on the reaction chamber walls, or reactions. Since it is impossible to clean the interior wall surface without cutting (perfect plasma cleaning), it is difficult to completely reset the inside of the reaction chamber.

  For this reason, recently, state monitoring and diagnosis are performed with high accuracy against subtle fluctuations in the reaction chamber wall state and subtle differences between apparatuses, and control is performed based on this to stabilize wafer processing characteristics. Technology development is becoming important. Parameters that determine wafer processing characteristics include pressure, gas flow rate, wall surface and wafer temperature, power supply matching characteristics, and the like. Developments to improve the accuracy of each are underway. Among them, examples of patent documents relating to monitoring and diagnosis of a reaction chamber and control of a power source and a matching unit are shown below.

  In Patent Document 1, after moving the stub of the impedance matching unit to a preset ignition point, the plasma is ignited, the plasma is ignited securely, and then the stub is moved to a matching point where the plasma is stable. Is. As the trajectory control, the operation trajectory is drawn from the initial set point to the plasma ignition point and the plasma stable point.

  Patent Document 2 shows that a sensor is attached in the middle of a path from an aligner to an electrode in a plasma processing apparatus, thereby detecting processing characteristics and variations thereof with high sensitivity.

Further, Patent Document 3 shows that impedance is measured during wafer processing, and empirical information is accumulated by creating a database together with wafer processing information and correlated with wafer processing characteristics. Yes.
JP-A-9-260096 JP 2003-174015 A JP 2004-39772 A

  In the plasma processing apparatus, it is essential to stabilize the processing characteristics over a long period of time in the same processing apparatus and to reduce the difference in the processing characteristics between different reaction chambers. However, the processing characteristics fluctuate due to an increase in deposits on the inner wall of the apparatus and wear of the inner wall. Even if the parts constituting the reaction chamber are manufactured with extremely high accuracy, a subtle difference occurs between the manufactured parts. For this reason, a difference in processing characteristics between a plurality of apparatuses may deviate from an allowable value.

  Also, once removed and reassembled during maintenance, the characteristics of the apparatus change due to differences in the assembled state during reassembly even for the same parts.

  As described above, in the plasma processing apparatus, even if the plasma density is fixed, the impedance is fixed, or the effective input power is fixed, the processing characteristics cannot always be fixed.

  In view of these problems, the present invention further enhances the ambient conditions such as the pressure and flow rate of the processing gas as a matter of course in order to stabilize the internal characteristics of the plasma processing apparatus and to stabilize the processing characteristics. It is based on the knowledge that it is effective to control the matching state between the power supply and the plasma while controlling the accuracy, and detects fluctuations in the processing characteristics of the plasma processing apparatus and further suppresses fluctuations. It is an object of the present invention to provide a plasma processing technique that can be used.

  In order to solve the above problems, the present invention employs the following means.

  A reaction vessel in which the inner side wall is insulated, a sample stage disposed in the reaction vessel, and an antenna are provided, and a high-frequency power is supplied to the antenna from a plasma generation power source to convert the treatment gas introduced into the reaction vessel into a plasma and sample A plasma processing apparatus for performing plasma processing on a sample placed on a table includes a matching unit for impedance matching between a plasma generating power source and a load circuit including an antenna. A sensor for measuring the impedance characteristics of the sensor, a matching arrival point when the load side is viewed from the input end of the matching unit, and a matching operation locus reaching the matching reaching point are changed according to the measured value of the sensor.

  Since the present invention has the above-described configuration, it is possible to detect a variation in the processing characteristics of the plasma processing apparatus and further suppress the variation.

[Example 1]
FIG. 1 is a diagram illustrating a plasma etching apparatus using UHF band electromagnetic waves as an example of the plasma processing apparatus according to the first embodiment.

  A reaction chamber 1 for plasma processing is provided with a dielectric vacuum window 2 for introducing UHF band electromagnetic waves for generating plasma 9 and a dielectric gas discharge plate 3 for introducing reactive processing gas. It is done. The reaction product resulting from the etching process is evacuated from the exhaust port 6 below the reaction chamber 1. The inner wall surface of the reaction chamber 1 is formed with a protective coating made of an insulating material 8 formed by anodizing the surface of an aluminum base material. The wafer 4 to be etched is placed on an electrostatic chuck formed of a dielectric (high resistance) film provided on the upper surface of the sample stage 5 and attracts the wafer 4 by electrostatic force.

  By filling helium gas between the wafer 4 and the electrostatic adsorption film, heat transfer with the sample stage 5 is ensured and the temperature of the wafer 4 is efficiently controlled. Further, a bias generating power source 13 for applying a high frequency bias to the wafer 4 and a DC power source necessary for adsorption by the electrostatic force are connected to the sample stage 5, and the wafer and the high resistance film are connected. The minute DC current flowing through the terminal can be monitored.

  In the reaction chamber 1, the reactive gas is discharged from the gas discharge plate 3 while maintaining a pressure of about 0.5 Pa to 10 Pa. In this state, a magnetic field is applied to the reaction chamber 1 by the magnetic field coil 7, and the UHF high frequency output from the plasma generating power source 12 is passed through the matching unit 11 to the reaction chamber 1 from the antenna 10 placed on the upper portion of the reaction chamber 1. By radiating electromagnetic waves, plasma 9 is generated in the reaction chamber 1 to perform an etching process.

  Here, a mixed gas of Cl 2 gas, HBr gas, and CF 4 gas was introduced into the processing apparatus shown in FIG. 1 to perform discharge, and the wafer on which the Poly-Si film was formed was etched.

  2 and 3 are diagrams for explaining processing for automatically correcting the variation in the etching processing characteristics of the wafer at this time. Note that the matching unit 11 in FIG. 1 automatically changes the circuit constant so that, for example, the input voltage reflection coefficient reaches a predetermined value (matching arrival point) each time plasma processing of each wafer is started. Further, as will be described later, it is possible to automatically change the matching arrival point and the matching locus (when the automatic change function of the matching arrival point and the matching locus is ON). The target matching arrival point and the matching trajectory to the matching arrival point can be stored in a database corresponding to the transition of the load voltage reflection coefficient, for example, and the matching unit 11 is based on the value stored in the database. Change the circuit constant of the matching unit.

  First, the automatic change function of the matching arrival point and the matching locus was turned off, and the input voltage reflection coefficient and the load voltage reflection coefficient were displayed on the Smith chart that can display impedance. In this state, the wafer was continuously processed. As a result, up to 2500 sheets could be processed in a stable discharge state. However, when the results of the wafer etching process were examined, as the number of processed wafers overlapped with the 500th, 1000th, 1500th,... Thus, it was found that the finished dimension of the fine pattern by etching was getting thinner. The finished size of the first sheet was 50 nm, whereas the 1500th sheet was 47 nm, the 2000th sheet was 46 nm, and the 2500th sheet was 45 nm. Further, it was later found out that an LSI device made from a wafer processed after the 2250th wafer has a characteristic defect. Furthermore, the discharge stability began to deteriorate from the point where 2500 sheets were exceeded. Since the wafer processing was advanced to 2600 sheets before this could be recognized, the result was that another 100 defective wafers were produced, and the wafer processing was stopped at the time of 2600 sheets.

  At this time, as a result of confirming the chart of the input voltage reflection coefficient and the load voltage reflection coefficient up to the 2500th sheet, the reflected wave was kept at 0 W as the first sheet. That is, as shown in FIG. 2A, the input voltage reflection coefficient is the same as that of the first sheet, and the origin 18 of the impedance chart is displayed throughout. However, as shown in FIG. 2B, it was found that the display value of the load voltage reflection coefficient was moved to a position 20 shifted by 10 ° counterclockwise as compared with the position 19 of the first sheet. did.

  The counterclockwise shift indicates that the electrostatic capacity in the high-frequency circuit for plasma generation has decreased, and this is because the thickness of the insulating coating deposited on the surface of the dielectric component above the reaction chamber 1 increases. It is shown that. Even if this deposited film was plasma cleaned with SF6 gas, there was no sign of a decrease, so unavoidably, the reaction chamber was opened to the atmosphere, the internal deposited film was swept out, the reaction chamber was reassembled, and then the vacuum was removed. After making it ready, wafer preparations were made, and only one wafer was processed as a trial. As a result, it was found that the finished size was returned to 50 nm as it was and the load voltage reflection coefficient was returned to the original position 19 on the chart. However, in this situation, from the second time onward, if there is a margin for safety, the number of processed sheets can only be limited to about 2000 at most.

  Next, the automatic change function of the alignment arrival point and alignment locus was changed to ON, and the continuous processing of the wafer was advanced again. Here, as the setting of the automatic change function, as shown in FIG. 3A, as the load power reflection coefficient shifts counterclockwise as shown in FIG. It was decided to shift the alignment arrival point in the direction of 0 ° on the chart. As the shift amount, the matching arrival point of the input voltage reflection coefficient is set to shift by 0.01 in the 0 ° direction on the chart per 1 ° of the counterclockwise shift amount of the load voltage reflection coefficient.

  FIG. 4 is a diagram illustrating a matching arrival point on the chart of the input voltage reflection coefficient when the load voltage reflection coefficient is shifted on the chart and a process of changing the matching operation locus reaching the matching arrival point.

  First, in step S1, load impedance is measured by a sensor arranged in the vicinity of the matching unit. In step 2, a load voltage reflection coefficient is calculated based on the measured value, and this value is plotted on a chart (for example, a Smith chart representing the load voltage reflection coefficient). In step 3, a deviation from the position on the chart as a reference is determined. If the amount of deviation is larger than the reference value, it means that an abnormality has occurred in the processing. Therefore, referring to the database 42 for determining the content of a preset warning, an alarm with the corresponding content is issued. In step S6, the process ends.

  If the deviation amount is equal to or smaller than the reference value in step 3, the matching arrival point or the matching locus reaching the matching arrival point is changed in step S4 in accordance with the transition of the load voltage reflection coefficient. When changing the matching arrival point and the matching locus to the matching arrival point, refer to the database 41 that stores the optimum matching point or the matching locus to the matching point corresponding to the transition of the load voltage reflection coefficient. Can do. This process can be realized by a program or the like. Also, the processing unit can be realized by hardware.

  When the processing proceeds according to the flow shown in FIG. 4, the matching locus on the chart indicating the input voltage reflection coefficient changes little by little as the arrival point shifts. As the process progressed, the processing characteristics of the wafer were examined with the finished dimensions of the fine pattern when the processing progressed to 2000 sheets, and it was found to be 49 nm. Furthermore, although continuous processing was advanced, deterioration of discharge stability was not particularly observed even at the 2500th sheet, and as a result, the processing could be stably performed up to 5000 sheets. At this point, the processing characteristics of the wafer are 47.5 nm when examined with the finished dimensions of the fine pattern. Further, when the characteristics of the LSI device prepared using the wafer that was etched at this time were examined, no device malfunction was found.

  After 5000 sheets, the load voltage reflection coefficient shift was saturated and almost stopped, and the finished dimension of the fine pattern did not become thinner than 47 nm. While confirming this situation, it was confirmed that the processing was continued up to 8000 sheets finally, and no increase in the device malfunction rate was observed in the wafers processed so far.

  As described above, it was found that by controlling the alignment arrival point and the trajectory to reach the plasma so as to keep the internal state of the plasma as constant as possible, it is possible to suppress the characteristic variation of the etching process of the fine pattern.

[Example 2]
FIG. 5 is a diagram for explaining a plasma etching apparatus using HF band electromagnetic waves (13.56 MHz) as an example of the plasma processing apparatus according to the second embodiment.

  The reaction chamber 1 for plasma treatment is provided with a conductive (silicon) gas discharge plate 3 for introducing a reactive processing gas at the top, and the inner wall surface of the reaction chamber 1 is anodized with the surface of an aluminum base material. A protective coating is formed by the insulating material 8 formed by processing. In this embodiment, this conductive gas discharge plate also serves as a ground electrode in the reaction chamber.

  The wafer 4 to be etched is placed on an electrostatic chuck formed of a dielectric (high resistance) film provided on the upper part of the sample stage 5 and attracts the wafer 4 by electrostatic force. By filling the space between the wafer 4 and the electrostatic adsorption film with helium gas, heat transfer with the sample stage 5 is ensured and the temperature of the wafer is controlled satisfactorily. In this apparatus, the HF band electromagnetic wave for generating the plasma 9 is applied to the sample stage 5 on which the wafer 4 is placed through the matching unit 11.

  Unlike the first embodiment, the second embodiment is a type of apparatus that applies an electromagnetic wave for plasma generation from the sample stage 5 side. As described above, the present invention can be applied when the electromagnetic wave for plasma generation is applied from the upper part of the reaction chamber or when it is applied through the sample stage from the lower part, and can be applied regardless of the frequency of the electromagnetic wave for plasma generation. . That is, speaking of the general name of the plasma apparatus, microwave plasma, inductively coupled plasma (ICP), or UHF plasma shown in the first embodiment as a system for introducing power for plasma generation through a dielectric window above the reaction chamber. And parallel plate type plasma in which power is introduced from the upper electrode installed inside the plasma, and parallel plate type plasma in which power is introduced from the lower sample stage (this embodiment 2). It can be applied to various plasma processing apparatuses.

  In FIG. 5, the reaction product exhausted by the etching process is evacuated from the exhaust port 6 below the reaction chamber 1. The sample stage 5 is connected to a bias generating power source 13 for applying a high frequency bias to the wafer 4 and a DC power source necessary for electrostatic adsorption. A reactive gas is typically discharged from the gas discharge plate 3 while maintaining a pressure of about 0.5 Pa to 10 Pa in the reaction chamber 1. In this state, HF high frequency output from the plasma generating power source 12 is radiated from the sample stage 5 into the reaction chamber 1 through the matching unit 11, thereby generating plasma 9 and performing an etching process. Here, discharge was performed using a mixed gas of CF 4 gas, O 2 gas, and Ar gas by the apparatus described with reference to FIG. 5, and the wafer on which the SiO 2 film was formed was etched.

  FIG. 6 is a diagram for explaining a process for automatically correcting a variation in etching process characteristics of a wafer.

  First, the automatic change function of the matching arrival point and the matching locus was turned off, and the input voltage reflection coefficient and the load voltage reflection coefficient were displayed on the impedance chart. In this state, the wafer was continuously processed. The processing was continued up to 2500 sheets, but when the results of the wafer etching process were examined, there was some shift in the etching shape up to the 2450th sheet, but it was somehow within the allowable range. However, the discharge stability began to deteriorate from the point where the number exceeded 2450, and when it was noticed, the wafer processing was advanced to 2500. For this reason, the wafer processing was stopped at the time of 2500 sheets.

  When the discharge stability is examined on the Smith chart of the input voltage reflection coefficient before the first wafer is etched, the unstable region 22 shown in FIG. 6B is a region labeled “one” in the figure. Although it was in a region away from the locus of the alignment operation, when the unstable region 22 was reconfirmed at the time of 2500 sheets, it was moved to the region indicated by “2500 sheets” in FIG. all right. In this situation, for the second and subsequent times, for safety reasons, the number of processed sheets must be limited to about 2000 at most.

  Therefore, the automatic change function of the alignment arrival point and the alignment trajectory is turned on, and the continuous processing of the wafer is advanced again. Here, as the setting of the automatic change function, as shown in FIG. 6A, as the load power reflection coefficient shifts counterclockwise, the matching arrival point on the chart of the input voltage reflection coefficient is changed here. Instead, as shown in FIG. 6B, only the alignment trajectory is shifted so as to avoid the unstable region.

  FIG. 4 shows a control flow based on this setting. In this setting, in step S4 in FIG. 4, the matching locus is changed with reference to the “database” storing the unstable region. As a result of proceeding the continuous processing in this state, no deterioration in discharge stability was observed especially up to the 2500th sheet, and there was no situation in which the processing characteristics were greatly deteriorated due to fluctuations in the discharge. Eventually, the process was continued as it was and processing was stably performed up to 5000 wafers. When the characteristics of an LSI device produced using an etched wafer were examined, no device malfunction was found. In this embodiment, since the control for changing the matching arrival point little by little was not performed, the etching shape slightly shifted, but even 5000 sheets were within the standard. Further, in this embodiment, by changing the locus of the alignment operation, in the processing after the 2450th sheet, the processing can be continued without causing instability of discharge, and there is an effect of avoiding instability by trajectory control. I was able to confirm.

Example 3
7 and 8 are diagrams for explaining an example of a change in the load voltage reflection coefficient when the components on the reaction chamber wall are worn. When the wafer is etched for a long period of time, the components on the reaction chamber wall wear and the processing characteristics change rapidly. An example of warning this change immediately before will be described.

  First, using the processing apparatus shown in FIG. 1, the processing for 8000 sheets and after was continued following Example 1. As a result, the processing could be stably continued up to 8500 sheets. However, in the processing from 8500 to 8600 sheets, the load voltage reflection coefficient has changed abruptly toward the inner side of the chart as shown in FIG. In addition, when the DC current flowing through the sample stage on which 1 to 8600 wafers are placed was confirmed, it was almost unchanged up to 8500 wafers, but it was about 10% lower than before at 8600 wafers. I understood.

  At this point, the continuous treatment was completed, and when the reaction chamber was opened to the atmosphere and the inside was thoroughly cleaned, the protective coating by the insulating material 8 near the lower end of the inner wall on the side of the reaction chamber disappeared due to wear. Turned out to be. Further, when processing characteristics of the 8600th wafer were examined, the finished dimension of the fine pattern was 49 nm, and the dimension began to increase again for some reason. Although it cannot be said that the fluctuation is extremely large, when the cross-sectional shape was examined, it was found that the shape was tapered and the shape started to change.

That is, when the load voltage reflection coefficient changes abruptly toward the inner side of the chart, it is a case where the protective coating by the insulating material 8 on the inner wall portion on the side surface of the reaction chamber is worn, and the underlying metal part is plasma. As a result, it was found that the plasma potential was lowered and the direct current flowing through the sample stage on which the etching wafer was placed was reduced, and the cross-sectional shape of the fine pattern began to deteriorate at this timing. Therefore, it is advantageous to issue a warning message about the wear of the protective coating due to the insulating material 8 on the surface of the metal part of the reaction chamber wall against the above phenomenon. A room sweep was performed. Next, in order to investigate another process, the etching gas was a mixed gas of CF4 and SF6, and the continuous processing was started using the processing apparatus shown in FIG. In this case, there was no significant change in the direct current flowing through the sample stage on which the etching wafer was placed during the processing of up to 4500 sheets. However, it was observed that the load voltage reflection coefficient changed clockwise in the chart as shown in FIG. The clockwise shift indicates that the capacitance has increased with respect to the high-frequency circuit for generating plasma, and this indicates the direction in which the surface of the dielectric part above the reaction chamber 1 is scraped. Therefore, when the processing was stopped at 4500 sheets and the inside of the reaction chamber was carefully examined, it was found that the quartz part on the upper surface of the reaction chamber was being scraped because plasma with a high fluorine (F) concentration was continued.

  As described above, when the protective coating of the insulating material on the inner wall part on the side of the reaction chamber is worn, and when the quartz part on the upper part of the reaction chamber is worn away, the change in characteristics on the Smith chart behaves differently. I understood it.

Example 4
Next, an example in which the plasma state is made constant when the assembly state of the reaction chamber parts in the same reaction chamber or the size of the individual parts is slightly different, and an example in which the difference in characteristics among a plurality of reaction chambers is reduced Will be described with reference to FIGS.

  The reaction chamber of the apparatus shown in FIG. 1 was disassembled and cleaned, and the worn parts were replaced with new ones and reassembled. Then, after the reaction chamber was evacuated, discharge of wafer processing was started by a normal procedure. At this time, when the load impedance with the reaction chamber side taken into account was measured, it was shifted by 5 ° counterclockwise as compared with the position 19 at the time of the first sheet processing on the load voltage reflection coefficient chart of FIG. It turns out that it is in a state.

  The deposits on the components in the reaction chamber have been properly cleaned, and the worn parts have been replaced, so that the initial state is restored in terms of deposition and wear. Therefore, this 5 ° is considered to be due to a subtle difference in the assembly state of the parts inside the reaction chamber or the dimensions of the individual parts.

  In Example 1, when the state inside the reaction chamber changes, the input voltage is shifted by 1 ° counterclockwise with respect to the position 19 at the time of processing the first sheet on the load voltage reflection coefficient chart of FIG. The matching arrival point of the reflection coefficient was controlled by setting to shift by 0.01 in the 0 ° direction of the chart.

  On the other hand, in the case where there is a shift of 5 ° due to the difference in the assembly state of the parts inside the reaction chamber or the size of the individual parts, as in the case of the first embodiment, the input for correcting the shift of the state inside the reaction chamber Should the value of the voltage reflection coefficient be shifted by 0.05 in the direction of 0 °, or the deposits on the components inside the reaction chamber have been cleaned and the worn parts have been replaced, so that they are shifted by 0.05. Instead, in order to clarify whether it should start from 0, that is, the origin, there are two ways: when the arrival value of the input voltage reflection coefficient is shifted by 0.05 in the direction of 0 ° and when it remains 0 Attempted wafer processing.

  As a result, it was found that when 0.05 shift was performed, the finished dimension of the fine pattern was 49.4 nm, and when it was kept at 0, it was 47.5 nm. As a result, even when the impedance characteristics shift due to differences in the assembly state of the parts inside the reaction chamber or the size of individual parts, the input is the same as when the internal state of the reaction chamber shifts due to deposits or wear. It was found that the shift in the final dimension of the fine pattern was smaller when the value of the voltage reflection coefficient was shifted. In other words, it has been found that the influence due to the difference in the assembly state of the components in the reaction chamber or the size of the individual components can be suppressed by the same control as in the first embodiment.

  Therefore, in order to confirm whether or not this can be applied to reduce the wafer processing characteristic difference among a plurality of reaction chambers, that is, to reduce the machine difference, four processing apparatuses A to D are prepared. The deposits on the parts were properly cleaned and worn parts were replaced.

  Next, the impedance characteristics of the reaction chamber in each processing apparatus are as follows: A is 6 ° counterclockwise, B is 0 ° with respect to the position 19 at the time of processing the first sheet on the load voltage reflection coefficient chart of FIG. It was found that C was shifted by 2 ° and D was shifted by −18 ° (that is, 18 ° in the clockwise direction). Here, only D is extremely misaligned, and the device issued a warning of an abnormal impedance characteristic. As a result, when the decomposition around the reaction chamber was confirmed, a small piece of metal was caught in the fitting part of the part. It turns out that it is poor. After reassembling, D was 4 ° in the counterclockwise direction, and the test shifted to a confirmation test of the finished dimensions of the fine pattern.

  As a result, as a result of testing without shifting the matching arrival point of the input voltage reflection coefficient, A was 47 nm, B was 50 nm, C was 49 nm, and D was 48 nm. On the other hand, the matching arrival point of the input voltage reflection coefficient is shifted in the direction of 0 ° by 0.06 for A, 0 for B, 0.02 for C, and 0.04 for D as shown in FIG. As a result of testing, A was 49.3 nm, B was 50 nm, C was 49.8 nm, and D was 49.5 nm. That is, it was confirmed that it can be applied to reduce machine differences.

  As described above, a warning can be issued when there is an impedance characteristic difference that deviates from a certain reference value. Further, when there is an impedance characteristic difference that does not deviate from a certain reference value, the influence of this characteristic difference on the processing characteristics of the fine pattern can be suppressed.

  In the first to fourth embodiments, the load impedance measured by the sensor and the impedance viewed from the matching unit input end related to the arrival point and locus of control by the matching unit are displayed or input to the load voltage reflection coefficient. Although the voltage reflection coefficient display is shown on the Smith chart, it is only necessary that the matching operation can be controlled in accordance with the change in the load impedance in the present invention. Therefore, analysis using the Smith chart is not an essential condition. It goes without saying that the matching operation can be controlled in the same manner if it is represented on a chart by other impedance notation, for example, R + jX notation, and the relationship with the processing characteristics is analyzed and grasped.

  Also, for example, when the dielectric parts in the reaction chamber are worn and the thickness is reduced, the load reflection coefficient on the chart shifts in the direction of increasing the capacitance, which is a movement in line with the theory. Is possible. However, there are cases where a logically sufficient explanation cannot be given regarding the direction of impedance shift due to a complicated reaction chamber configuration, a difference in assembly state that cannot be grasped, an abnormal discharge phenomenon, and the like. Even in such a case, it is possible to give an empirical control instruction by grasping the tendency in advance and storing it in the database, thereby suppressing characteristic fluctuations.

  As explained above, there are subtle differences in characteristics when manufacturing multiple reaction chambers, and there are subtle differences in processing characteristics due to accumulation of deposits on the reaction chamber walls and wear of the reaction chamber walls. However, it is possible to monitor this with high accuracy and recognize the direction in which the characteristics are shifting, and then change the matching characteristics in the direction that aligns the characteristics. The characteristic variation with respect to can be canceled. As a result, parts can be replaced from the need to return the wafer processing characteristics to their original state even when the characteristics are deviated beyond a certain reference value. As a result, the operating rate is improved and the cost of consumable parts can be reduced.

  Further, since a warning can be issued when the shift becomes larger than a certain reference value, it is possible to prevent a situation in which many defects are created in the LSI device. In addition, it is possible to monitor the state of the apparatus, correct characteristics, warn of characteristic deviation, and determine the reason for characteristic deviation for each nuclear reaction chamber. For this reason, not only the occurrence of defects can be prevented, but also information useful for mass production management can be issued such as the timing of sweeping out the reaction chamber and the replacement timing of consumable parts can be automatically indicated.

It is a figure explaining the plasma etching apparatus using the electromagnetic wave of a UHF band. It is a figure explaining the process for correct | amending automatically the fluctuation | variation of the etching process characteristic of a wafer. It is a figure explaining the process for correct | amending automatically the fluctuation | variation of the etching process characteristic of a wafer. It is a figure explaining the change process of the matching operation | movement locus | trajectory to the matching arrival point on the chart of the input voltage reflection coefficient when the load voltage reflection coefficient is shifted on the chart, and the matching arrival point. It is a figure explaining the plasma etching apparatus using the electromagnetic wave of HF band. It is a figure explaining the process for correct | amending automatically the fluctuation | variation of the etching process characteristic of a wafer. It is a figure explaining the example of the change of the load voltage reflection coefficient when the components of the reaction chamber wall are worn. It is a figure explaining the example of the change of the load voltage reflection coefficient when the components of the reaction chamber wall are worn.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reaction chamber 2 Dielectric vacuum window 3 Gas discharge plate 4 Wafer 5 Sample stand 6 Exhaust port 7 Magnetic coil 8 Insulation material 9 Plasma 10 Antenna 11 Matching device 12 Power source for plasma generation 13 Power source for bias generation 18 Input voltage reflection coefficient chart Origin 19 Position on first load processing on load voltage reflection coefficient chart 20 Position shifted by 10 ° counterclockwise 21 Alignment operation start point 22 Unstable region 23 Conductive gas release plate

Claims (9)

A reaction vessel with an insulated inner side wall;
A sample stage arranged in the reaction vessel and an antenna are provided, and a high-frequency power is supplied to the antenna from a plasma generating power source to convert the processing gas introduced into the reaction vessel into plasma and plasma treatment is performed on the sample placed on the sample stage. In the plasma processing apparatus for applying
A matching unit is provided for impedance matching between the plasma generation power source and the load circuit including the antenna.
The matching unit changes the impedance characteristics on the load circuit side, the matching arrival point seen from the input side of the matching unit from the input side of the matching unit, and the matching operation locus reaching the matching arrival point according to the measured value of the sensor A plasma processing apparatus. The plasma processing apparatus according to claim 1,
A plasma processing apparatus that issues an alarm when a change in a measured impedance characteristic value exceeds a predetermined value. The plasma processing apparatus according to claim 1,
A plasma processing apparatus, wherein wear of a protective coating on a reaction vessel inner side wall or scraping of an upper quartz component of a reaction vessel is determined based on a measured change direction of an impedance characteristic value. The plasma processing apparatus according to claim 1,
A plasma processing apparatus characterized in that an alignment operation locus to an alignment arrival point is set so as to avoid an unstable region of plasma. The plasma processing apparatus according to claim 4, wherein
The matching device includes a database that stores data representing an unstable region of plasma as a range of an input voltage reflection coefficient. The plasma processing apparatus according to claim 1,
A plasma processing apparatus, wherein high-frequency power from a power source for plasma generation is supplied to a sample stage and the sample stage functions as an antenna. The plasma processing apparatus according to claim 1,
The impedance characteristic on the load circuit side measured by the sensor is the load power reflection coefficient, and the matching arrival point on the Smith chart of the input voltage reflection coefficient is shifted according to the shift of the load power reflection coefficient on the Smith chart. Processing equipment. The plasma processing apparatus according to claim 7, wherein
A plasma having a database storing a correspondence relationship between the shift direction and amount of the load power reflection coefficient on the Smith chart and the shift direction and amount of the matching arrival point on the Smith chart of the input voltage reflection coefficient Processing equipment. The plasma processing apparatus according to claim 1,
A plasma processing apparatus comprising means for adjusting a processing dimension by changing a matching arrival point on a Smith chart of an input voltage reflection coefficient.

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