JP2010277695A - Plasma treatment device, and plasma treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment device and a plasma treatment method, capable of adequately detecting a discharge state by a system of monitoring the discharge state with a discharge detecting sensor. <P>SOLUTION: A discharge starting determination period 36, a discharge starting determination threshold value 37 and an abnormal discharge determination threshold value 38 are set by determination parameter setting section 34 on the basis of the potential change data obtained by execution of test discharge with a treatment condition set upon the plasma treatment execution. Upon an execution of the plasma treatment, it is determined whether the plasma discharge has normally started or not by comparing the potential change in a discharge starting determination period with the discharge starting determining threshold value, and occurrence of abnormal discharge is determined by comparing the potential change detected after the discharge starting determining period with the abnormal discharge determining threshold value. Thus, detection of the discharge state can be precisely carried out by adequately and easily presetting the determining parameters. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method for plasma processing a processing object such as a substrate.

  Plasma treatment is known as a surface treatment method such as cleaning and etching of a processing object such as a substrate on which an electronic component is mounted. In plasma processing, a substrate to be processed is placed in a vacuum chamber that forms a processing chamber, a plasma discharge is generated in the processing chamber, and the resulting ions, electrons, and radicals act on the surface of the substrate. A desired surface treatment is performed. In order to perform this plasma processing stably with good processing quality, it is premised that the plasma is generated correctly according to the discharge conditions set in advance according to the processing purpose. For the purpose of monitoring the generation state, a plasma processing apparatus including a discharge detection sensor that detects a state of plasma discharge in a processing chamber is known (see Patent Documents 1 to 4).

  In the prior art shown in these patent documents, a potential change induced according to a plasma state change in the processing chamber is detected as a potential change waveform by a discharge detection sensor, and the detection result is compared with a preset threshold value. Thus, a predetermined item such as whether or not the plasma discharge has started normally or whether or not the abnormal discharge has occurred is determined. That is, since a potential change having a specific pattern and amplitude occurs at the start of discharge, the waveform of this potential change is detected in a predetermined time zone starting from the timing when the high-frequency power is turned on. It is determined that the discharge has started normally. Further, it is determined that an abnormal discharge has occurred by detecting a peak-like waveform having a specific amplitude value in a state where the plasma discharge is continuously generated. In order to make such a determination, each plasma processing apparatus has various time parameters for determination, for example, a time parameter that defines the above-mentioned time zone for detecting the start of discharge, and a peculiarity that is regarded as abnormal discharge. A threshold value for detecting a waveform having a large amplitude value is set in advance.

JP 2009-48879 A JP 2009-48880 A JP 2009-48881 A JP 2009-48882 A

  However, in the above-described prior art, when the plasma processing conditions are changed in accordance with the production target in the same plasma processing apparatus, determination results such as the determination of the start of discharge and the determination of the occurrence of abnormal discharge are not necessarily accurately performed, and erroneous determination It may become. The waveform of the potential change detected by the discharge detection sensor is not uniform, and depends on several conditions such as the processing conditions applied to the plasma processing, that is, the processing pressure, the type of gas used for the plasma discharge, and the gas flow rate. In addition, it also changes depending on conditions that change over time, such as a fouling state in the processing chamber.

However, in the prior art, determination parameters such as time parameters and threshold values used for determination are fixedly set with emphasis on versatility so as to be able to handle processing conditions in a wide range as much as possible. For this reason, when the user changes the plasma processing conditions according to the type of product to be produced, or when the apparatus state changes with time, the fixed determination parameter is always appropriate for the purpose. However, there is a case where an erroneous determination result is caused as a result.

  For example, the detection of the abnormal discharge described above is started after the end of a time zone defined by a time parameter fixedly set in advance. If the setting of this time parameter is inappropriate, the following is performed. Cause inconvenience. That is, when the set time parameter is shorter than the appropriate time, it is erroneously determined that the discharge is not started although the normal discharge is actually started. Conversely, if the time parameter is longer than the appropriate time, there will be a time period during which abnormal discharge is not monitored between the actual discharge start and the time specified by the time parameter. Therefore, the discharge state suitable for the original purpose cannot be properly detected. As described above, it is difficult to properly detect the discharge state in the conventional plasma processing apparatus that monitors the discharge state by the discharge detection sensor because the determination parameter is fixedly set. There was a problem.

  Therefore, an object of the present invention is to provide a plasma processing apparatus and a plasma processing method capable of appropriately detecting a discharge state in a configuration in which the discharge state is monitored by a discharge detection sensor.

  A plasma processing apparatus according to the present invention includes a vacuum chamber that forms a processing chamber that accommodates a processing object, a vacuum exhaust unit that evacuates the processing chamber, and a gas supply unit that supplies a gas for generating plasma discharge into the processing chamber Plasma generating means for generating plasma discharge by applying high-frequency power to the plasma discharge generating gas in the processing chamber, the vacuum exhaust section and the gas supply section based on preset processing conditions, and A plate-like member having a control unit for controlling the plasma generating means and one surface and the other surface, one surface of which is mounted on the vacuum chamber in a state facing the plasma discharge generated in the processing chamber. A discharge detection sensor having at least a dielectric member formed and a probe electrode disposed on the other surface, and the plasma on the probe electrode A plasma processing apparatus comprising a plasma discharge monitoring unit that detects a potential change induced in response to a change in electricity and determines a state of the plasma discharge and outputs a determination result to the control unit. Comprises a test discharge execution unit for executing a test discharge for acquiring the potential change data corresponding to the processing condition, and the plasma discharge monitoring unit stores the potential change data acquired by the test discharge. And a time until the plasma discharge is stabilized after the plasma discharge is started from the start of the output of the high frequency power by the plasma generating means based on the potential change data stored in the potential change storage unit. The discharge start determination time set based on the time between the output of the high frequency power and the discharge start determination time elapses. A determination parameter setting unit for setting a discharge start determination threshold used for determining whether or not there is a discharge start and an abnormal discharge determination threshold used as a threshold for detecting an abnormal discharge after the discharge start determination time has elapsed; Determining whether the plasma discharge has started normally by comparing the potential change detected immediately after the high-frequency power is output and before the discharge start determination time elapses with the discharge start determination threshold value And a discharge state determination unit that determines the presence or absence of abnormal discharge by comparing a potential change detected after the discharge start determination time has elapsed with the abnormal discharge determination threshold.

The plasma processing method of the present invention includes a vacuum chamber that forms a processing chamber that accommodates a processing object, a vacuum exhaust unit that evacuates the processing chamber, and a gas supply unit that supplies a gas for generating plasma discharge into the processing chamber. Plasma generating means for generating plasma discharge by applying high-frequency power to the plasma discharge generating gas in the processing chamber, the vacuum exhaust section and the gas supply section based on preset processing conditions, and A plate-like member having a control unit for controlling the plasma generating means and one surface and the other surface, one surface of which is mounted on the vacuum chamber in a state facing the plasma discharge generated in the processing chamber. A discharge detection sensor having at least a dielectric member formed and a probe electrode disposed on the other surface, and the plasma on the probe electrode The plasma processing apparatus includes a plasma discharge monitoring unit that detects a potential change induced according to a change in electricity and determines a state of the plasma discharge and outputs a determination result to the control unit. A plasma processing method for performing the plasma processing, wherein a processing pressure is set in the processing chamber, and the processing conditions of the plasma processing including the processing pressure in the processing chamber, the type of gas for generating the plasma discharge, the flow rate, and the output of the high frequency power are set. Performing a test discharge for acquiring the potential change data corresponding to the processing condition, and storing the potential change data obtained by the test discharge in a potential change storage unit; and From the potential change data stored in the potential change storage unit in the potential change storage step, the high frequency generated by the plasma generating means The discharge start determination time set based on the time from the start of the power output to the start of the plasma discharge to the stabilization of the plasma discharge, and the discharge start determination time after the high-frequency power is output A determination parameter for setting a discharge start determination threshold value used for determining whether or not there is a discharge start and an abnormal discharge determination threshold value used as a threshold value for detecting an abnormal discharge after the discharge start determination time has elapsed A setting step and a plasma processing step of performing plasma processing on the processing object under the processing conditions, and in the plasma processing step, the discharge start determination time elapses immediately after the high-frequency power is output. The plasma discharge is corrected by comparing the potential change detected before the discharge with the discharge start determination threshold. A discharge start determination stage for determining whether or not the discharge has been always started, and a discharge state determination for determining presence or absence of abnormal discharge by comparing a potential change detected after the discharge start determination time has elapsed with the abnormal discharge determination threshold. Including stages.

  According to the present invention, the test discharge is performed according to the processing conditions set when the plasma processing is performed, the potential change data corresponding to the processing conditions is acquired, and then the discharge start determination time is based on the potential change data. Set the determination parameters such as the threshold value for starting discharge and the threshold value for determining abnormal discharge, and start discharging the potential change detected immediately after the high frequency power is output until the discharge start determination time elapses in the plasma processing execution stage. A mode in which it is determined whether or not plasma discharge has been started normally by comparing with a determination threshold value, and a potential change detected after the discharge start determination time has elapsed is compared with an abnormal discharge determination threshold value to determine the presence or absence of abnormal discharge By adopting this plasma processing method, the judgment parameters can be set appropriately and easily, and the discharge detection sensor In the configuration for performing the monitoring, the detection of the discharge state can be appropriately performed.

Sectional drawing of the plasma processing apparatus of one embodiment of this invention Structure explanatory drawing of the discharge detection sensor used for the plasma processing apparatus of one embodiment of this invention The block diagram which shows the structure and function of the control part of the plasma processing apparatus of one embodiment of this invention Explanatory drawing of the electric potential change waveform detected by the discharge detection sensor in the plasma processing apparatus of one embodiment of this invention Flow chart of automatic determination parameter setting in plasma processing method of one embodiment of the present invention The graph which shows the discharge waveform obtained by the test discharge in the plasma processing method of one embodiment of this invention The graph which shows the discharge waveform obtained by the test discharge in the plasma processing method of one embodiment of this invention

  Next, embodiments of the present invention will be described with reference to the drawings. First, the structure of the plasma processing apparatus will be described with reference to FIG. In FIG. 1, a vacuum chamber 3 is configured by disposing a lid portion 2 on a horizontal base portion 1 so as to be movable up and down by elevating means (not shown). The vacuum chamber 3 is closed when the lid portion 2 is lowered and is in contact with the upper surface of the base portion 1 via the seal member 4, and the sealed space surrounded by the base portion 1 and the lid portion 2 holds the object to be processed. A processing chamber 3a that accommodates and performs plasma processing is formed. An electrode portion 5 is disposed in the processing chamber 3a, and the electrode portion 5 is attached to an opening portion 1a provided in the base portion 1 via an insulating member 6 from below. An insulator 7 is mounted on the upper surface of the electrode unit 5, and the substrate 9, which is the object to be processed, is guided by the guide member 8 on both sides of the upper surface of the insulator 7 in the substrate transport direction (perpendicular to the paper surface). It is brought in.

  A vent valve 12, a vacuum gauge 15, a gas supply valve 13, and a vacuum valve 14 are connected to the opening 1 b provided in the base portion 1 through a pipe line 11. Further, the gas supply valve 13 and the vacuum valve 14 are connected to a gas supply unit 16 and a vacuum pump 17, respectively. By opening the vacuum valve 14 while the vacuum pump 17 is driven, the inside of the processing chamber 3a is evacuated. The degree of vacuum at this time is detected by the vacuum gauge 15. The vacuum valve 14 and the vacuum pump 17 constitute a vacuum exhaust unit that exhausts the inside of the processing chamber 3a. Further, by opening the gas supply valve 13, a gas for generating plasma discharge is supplied from the gas supply unit 16 into the processing chamber 3a. The gas supply unit 16 has a built-in flow rate adjustment function, and can supply an arbitrary supply amount of plasma discharge generating gas into the processing chamber 3a. By opening the vent valve 12, the atmosphere is introduced into the processing chamber 3a when the vacuum breaks.

  A high frequency power supply unit 19 is electrically connected to the electrode unit 5 via a matching unit 18. By driving the high frequency power supply unit 19 in a state where gas is supplied into the evacuated processing chamber 3a, a high frequency voltage is applied between the electrode unit 5 and the lid unit 2 grounded to the ground unit 10, Thereby, plasma discharge is generated in the processing chamber 3a. The matching unit 18 has a function of matching the impedance of the high-frequency power supply unit 19 with the plasma discharge circuit that generates plasma discharge in the processing chamber 3a. The electrode unit 5, the matching unit 18 and the high frequency power supply unit 19 serve as plasma generating means for generating plasma discharge by applying high frequency power to the plasma discharge generating gas in the processing chamber 3a.

  A circular opening 2 a that functions as a viewing window for viewing the inside of the processing chamber 3 a from the outside of the vacuum chamber 3 is provided on the side surface of the lid 2. A discharge detection sensor 23 including a dielectric member 21 and a probe electrode unit 22 is fixed to the opening 2 a from the outside of the lid 2 by a support member 24. Here, the configuration of the discharge detection sensor 23 will be described with reference to FIG. A dielectric member 21 made of optically transparent glass is attached to the opening 2 a provided in the lid 2. Inside the processing chamber 3a, a plasma discharge is generated between the electrode portion 5 and the lid portion 2, and the dielectric member 21 is vacuumed in such a manner that one surface faces the plasma discharge generated in the processing chamber 3a. It is attached to an opening 2 a provided in the chamber 3.

A probe electrode unit 22 is mounted on the other surface of the dielectric member 21, that is, the surface facing the outside of the vacuum chamber 3. The probe electrode unit 22 is an integral part in which the probe electrode 22b is formed on one surface of the glass plate 22a and the shield electrode 22c is formed on the other surface, and the probe electrode unit 22 is attached to the dielectric member 21 and discharged. When forming the detection sensor 23, the probe electrode 22 b is supported on the lid 2 by a support member 24 made of a conductive metal in a state where the probe electrode 22 b is in close contact with the outer surface (the other surface) of the dielectric member 21. That is, the discharge detection sensor 23 has a plate-like dielectric member 21 attached to the vacuum chamber 3 so that one surface faces the plasma discharge generated in the processing chamber 3a and the other surface of the dielectric member 21. The probe electrode 22b is disposed at least. The probe electrode 22b is connected to the plasma discharge monitoring unit 20 through the detection lead wire 22d.

  In a state where plasma discharge is generated inside the processing chamber 3a, the probe electrode 22b is a space charge layer formed at the interface between the dielectric member 21 and the plasma P generated in the processing chamber 3a and the dielectric member 21. It is in a state of being electrically connected to the plasma P through the sheath S. That is, as shown in FIG. 2, an electric circuit is formed in which a capacitor C1 formed by the dielectric member 21, a capacitor C2 having a capacity corresponding to the sheath S, and a resistor R of the plasma P are connected in series, and the probe is formed. A potential corresponding to the state of the plasma P is induced in the electrode 22b. In the present embodiment, the potential of the probe electrode 22b is guided to the plasma discharge monitoring unit 20 by the detection lead wire 22d, and the potential change according to the state of the plasma P is monitored by the plasma discharge monitoring unit 20, whereby the inside of the processing chamber 3a. The plasma discharge state in is monitored. The plasma discharge monitoring unit 20 detects a potential change induced in the probe electrode 22b according to the change in the plasma discharge in the processing chamber 3a, determines the state of the plasma discharge, and controls the control unit 25 (also FIG. 3). The judgment result is output to

  That is, when abnormal discharge or the like occurs around the substrate 9 placed on the electrode unit 5 inside the processing chamber 3a, the state of the plasma P inside the processing chamber 3a changes. This change is detected as a change in the potential of the probe electrode 22b because it changes the impedance of the circuit described above. This potential change is detected with extremely high sensitivity, and it has a feature that it can accurately detect even a weak fluctuation that could hardly be detected by a conventional method. The shield electrode 22c has a function of electrically shielding the outer surface side of the probe electrode 22b, and the electric charge generated in the shield electrode 22c is released to the grounded lid portion 2 through the conductive support member 24. Thereby, the noise with respect to the electric potential change induced by the probe electrode 22b is reduced.

  In the present embodiment, both the probe electrode 22b and the shield electrode 22c are formed by coating the surface of the glass plate 22a with a transparent conductive material such as ITO in the form of a film. Thereby, in a state where the discharge detection sensor 23 is mounted in the opening 2a, the inside of the processing chamber 3a can be visually recognized from the outside of the lid 2 through the opening 2a. That is, in the discharge detection sensor 23 shown in the present embodiment, the dielectric member 21 is optically transparent attached to the opening 2a (view window) for viewing the inside of the processing chamber 3a from the outside of the vacuum chamber 3. The probe electrode 22b is made of an optically transparent conductive material.

  With such a configuration, it is possible to use both the observation window for visually recognizing the inside of the processing chamber 3a and the probe electrode 22b for monitoring the plasma discharge state. Further, since the dielectric member 21 is exposed to the plasma P in the processing chamber 3a, surface wear occurs, and it is necessary to replace it at predetermined intervals. Also in this case, since the probe electrode unit 22 and the dielectric member 21 are separate parts, only the dielectric member 21 as a consumable part needs to be replaced, and the probe electrode unit 22 does not need to be replaced.

The plasma processing apparatus includes a control unit 25 that performs overall operation control. The control unit 25 controls the vent valve 12, the gas supply valve 13, the vacuum valve 14, the vacuum gauge 15, the gas supply unit 16, the vacuum pump 17, and the high frequency power supply unit 19, thereby performing each operation necessary for plasma processing. Is done. The control unit 25 has a function of controlling the plasma discharge monitoring unit 20 and receiving a detection result from the plasma discharge monitoring unit 20 and performing necessary control processing. An operation / input unit 26 and a display unit 27 are connected to the control unit 25, and the operation / input unit 26 inputs data such as various operation inputs necessary for execution of plasma processing and data for setting processing conditions. In addition to displaying an operation screen at the time of input by the operation / input unit 26, the display unit 27 displays the determination result determined by the control unit 25 based on the detection result of the plasma discharge monitoring unit 20.

  Next, the configurations and functions of the control unit 25 and the plasma discharge monitoring unit 20 will be described with reference to FIG. In FIG. 3, the control unit 25 includes a processing condition storage unit 39, a plasma processing execution unit 40, and a test discharge execution unit 41. The processing condition storage unit 39 stores processing conditions set during the plasma processing, that is, data such as processing pressure in the processing chamber 3a, type of plasma discharge generating gas, flow rate, and output of high-frequency power. The plasma processing execution unit 40 controls the vent valve 12, the gas supply valve 13, the vacuum valve 14, the vacuum gauge 15, the gas supply unit 16, the vacuum pump 17, and the high frequency power supply unit 19 based on the set processing conditions. Execute plasma processing. The test discharge execution unit 41 executes test discharge for acquiring potential change data corresponding to the processing conditions. In the present embodiment, each time the plasma processing conditions are updated, the plasma discharge monitoring unit 20 sets a determination parameter used for a discharge start determination or an abnormal discharge determination. By performing a test discharge for acquiring potential change data corresponding to various processing conditions and analyzing the acquired potential change data, an appropriate determination parameter is set according to the processing conditions. Yes.

  The plasma discharge monitoring unit 20 includes an AMP (amplifying device) 31, an A / D converter 32, a potential change storage unit 33, a determination parameter setting unit 34, and a discharge state determination unit 35. The AMP 31 amplifies the potential change of the probe electrode 22b transmitted through the detection lead 22d. The A / D converter 32 AD converts the potential change signal amplified by the AMP 31. A voltage displacement signal AD-converted by the A / D converter 32, that is, a digital signal indicating a voltage change is stored in the potential change storage unit 33. Similarly, the potential change data acquired by the test discharge executed by the test discharge execution unit 41 is also stored in the potential change storage unit 33.

  The discharge state determination unit 35 performs a process of determining the discharge state in the processing chamber 3 a based on the potential change data stored in the potential change storage unit 33. That is, the discharge state determination unit 35 includes a discharge start determination unit 35a, an abnormal discharge determination unit 35b, and a determination parameter storage unit 35c. The determination parameter storage unit 35c includes a discharge start determination time 36 (in the figure, a determination parameter). A discharge start determination time TA (illustrated), a discharge start determination threshold 37 (upper threshold V1, lower threshold V2), and an abnormal discharge determination threshold 38 (upper threshold V3, lower threshold V4) are stored. The determination parameter setting unit 34 has a function of setting determination parameters used in the determination of the discharge state by the discharge state determination unit 35 based on the potential change data acquired by the test discharge and stored in the potential change storage unit 33. is doing.

  Here, the determination process of the discharge state performed by the discharge state determination part 35 is demonstrated with reference to FIG. FIG. 4 shows a waveform of a potential change detected by the discharge detection sensor 23 during operation of the plasma processing apparatus. First, when the application of the high frequency power supply by the high frequency power supply unit 19 is started, a waveform W1 indicating a specific waveform pattern that swings on both the positive and negative sides exceeding the upper threshold value V1 and the lower threshold value V2 of the discharge start determination threshold value 37 is detected. Then, when the waveform W1 is detected within the discharge start determination time TA set in advance as a time zone in which the waveform W1 should be detected, it is determined that the plasma discharge has started normally in the processing chamber 3a. This determination process is performed by the discharge start determination unit 35a, and it is determined that the discharge starts when the potential change exceeds the upper threshold value V1 and the lower threshold value V2 within the discharge start determination time TA.

In addition, after the discharge start determination time TA has elapsed, the presence or absence of abnormal discharge is monitored. Here, the abnormal discharge is an abnormal discharge generated between the substrate 9 placed on the electrode unit 5 and the electrode unit 5, and the substrate 9 is warped and placed on the electrode unit 5. This occurs when there is a gap between the substrate 9 and the insulator 7 in the state. In this case, an abnormal discharge is generated in the processing chamber 3a by detecting a waveform W2 in which the potential change fluctuates beyond the upper threshold V3 and the lower threshold V4 of the abnormal discharge determination threshold 38 on the positive side or the negative side, respectively. It is determined that This determination process is performed by the abnormal discharge determination unit 35b, and it is determined that abnormal discharge has occurred when the potential change exceeds the upper threshold value V3 and the lower threshold value V4 after the discharge start determination time TA has elapsed.

  Here, the determination parameter automatic setting process executed by the determination parameter setting unit 34 will be described with reference to FIGS. 6 and 7 in accordance with the flow of FIG. This determination parameter automatic setting processing is performed when a processing condition is newly updated in the plasma processing method for the substrate 9 as a processing target using the plasma processing apparatus shown in FIG. When the determination parameter needs to be updated, the process is executed prior to the start of the plasma processing operation.

  First, in FIG. 5, a processing condition setting request for plasma processing is made (ST1). That is, an input screen prompting the machine operator to select and input a new processing condition is displayed on the display unit 27, and the machine operator is read from the processing condition storage unit 39 and displayed on the screen of the display unit 27. New processing conditions are set by executing selection operations and numerical input for various items of processing conditions, for example, processing pressure, type of gas for generating plasma discharge, flow rate, and output value of high-frequency power (processing conditions) Setting stage). By performing this setting input, the plasma processing apparatus is ready for test discharge execution, and enters a state of waiting for test discharge start input. If the start input is confirmed here (ST2), a series of processing cycles for the test discharge is started.

  First, the vacuum chamber 3 is closed (ST3), and then the vacuum valve 14 is opened to start evacuation by the vacuum pump 17 (ST4). Then, it is monitored that the pressure in the processing chamber 3a reaches a predetermined pressure P1 (ST5). If the pressure is confirmed to reach, the gas supply valve 13 is opened, and plasma from the gas supply unit 16 into the processing chamber 3a is opened. Supply of the gas for generating discharge is started (ST6). Next, the processing pressure in the processing chamber 3a is monitored (ST7), and if the set pressure P2 determined by the processing conditions is stabilized, the high-frequency power supply unit 19 is operated to output high-frequency power, and the potential change data is output. Data recording processing to be written in the potential change storage unit 33 is started (ST8). That is, in (ST3) to (ST8), a test discharge for acquiring data of potential change corresponding to the processing condition is executed, and the data of potential change obtained by this test discharge is stored in the potential change storage unit 33. (Potential change storage stage).

  Thereafter, the timer measures the discharge time until 5 seconds elapse (ST9). If 5 seconds elapses, the gas supply valve 13 is closed and the supply of the plasma discharge generating gas is stopped (ST10). Next, the vacuum valve 14 is closed to stop evacuation (ST11), and the vent valve 12 is opened to open the processing chamber 3a to the atmosphere (ST12), and then the vacuum chamber 3 is opened (ST13). The number of processing cycles described above is counted (ST14), and the subsequent processing is repeatedly executed until the number of discharges reaches 5 (ST2). If it is confirmed in (ST14) that the number of discharges has reached 5, the potential change data stored in the potential change storage unit 33 is read out, and data for setting the determination parameter described below Processing is performed according to the processing procedures of (ST15) to (ST18) (determination parameter setting stage).

This data processing will be described with reference to FIGS. FIG. 6A shows, in time series, data on potential changes acquired in (ST8) and (ST9) from the start of application of high-frequency power to 5 seconds. T11 shown in FIG. 6A indicates an initial time until the discharge is stabilized after the high frequency power is applied in the test discharge and the plasma discharge is started. T10 after the initial time T11 is the plasma. The stable discharge time performed in the state where discharge was stable is shown. In the determination parameter setting stage, first, the magnitude of the fluctuation range in the potential change data corresponding to the plasma discharge performed at the stable discharge time T10 is obtained from the potential change data acquired in the test discharge. That is, the data obtained by the test discharge is acquired at the end [T] of the test discharge time zone in which the discharge state is considered to be most stable (here, from 4 seconds to 5 seconds after the start of the test discharge). The fluctuation range VB is obtained for the obtained data. Here, the magnitude of the fluctuation range VB indicating the variation range of the acquired plurality of potential change data is represented by an upper value V10 that is a representative value on the positive voltage side and a lower value that is a representative value on the negative voltage side. It is defined by the value V12.

  FIG. 6B shows an enlarged view of the data acquired at the end [T] of the potential change data shown in FIG. The upper value V10 and the lower value V12 are obtained by statistically processing a plurality of potential change data acquired in the final period [T]. That is, out of a plurality of data d actually acquired at the end [T], k pieces of data d (here, k = 3) are excluded in descending order of the degree of separation from the 0 potential in the positive and negative directions, The maximum value and the minimum value of the data are used as an upper value V10 and a lower value V12.

  That is, in the example shown in FIG. 6B, three data d of d (+1) and two d (+2) are excluded in descending order of the degree of separation in the positive voltage direction, and the maximum value of the remaining data d is excluded. The voltage value of d (+4) is taken as the upper value V10. Similarly, three data d of d (−1) and two d (−2) are excluded in descending order of the degree of separation in the negative voltage direction, and the minimum value d (−4) of the remaining data d is The voltage value is set to the lower value V12. In the above example, the smaller the number k excluding the data d is set, the more precisely the fluctuation range VB is defined. The larger the number k is set, the more the fluctuation range VB is defined. .

  In other words, the setting of the number k is n when the upper limit value and the lower limit value to be taken in as a normal range are defined by a multiple (n) of the standard deviation σ in a plurality of data regarded as a normal distribution and treated statistically. This is equivalent to setting the number. That is, the upper value V10 and the lower value V12 thus obtained are stable state amplitudes indicating the magnitude of the fluctuation range VB in the potential change corresponding to the plasma discharge performed in a stable state by a statistical representative value. It is data.

  In the determination parameter setting stage, the upper value V10 and the lower value V12 are thus detected (ST15). Based on the upper value V10 and the lower value V12, a discharge start determination threshold 37 (upper threshold V1, lower threshold V2) is calculated (ST16). Here, as the discharge start determination threshold 37 (upper threshold V1, lower threshold V2), voltages obtained by multiplying the upper value V10 and the lower value V12 by a constant (for example, V1 = V10 × 1.5, V2 = V12 × 1.5), respectively. The value is used. Next, the abnormal discharge determination threshold value 38 (upper threshold value V3, lower threshold value V4) is calculated (ST17). Here, the voltage value of the upper threshold value V1 of the discharge start determination threshold 37 is used as it is as the upper threshold value V3, and is set to a fixed voltage value (for example, −3 V) as the lower threshold value V4.

  Next, the discharge start determination time TA is calculated (ST18). In the present embodiment, the discharge start determination time TA is set based on the initial time T11 obtained as a result of the test discharge. The initial time T11 is determined by the method described below. That is, the potential change data shown in FIG. 6A is traced retroactively from the time point after 5 seconds toward the time point when the test discharge is started, and the upper value V10 and the lower value determined in (ST15). The presence / absence of data d whose data value protrudes from the fluctuation range VB defined by V12 is detected.

At this time, as shown in FIG. 7, when the data do protruding from the fluctuation range VB is detected, the data d is ignored and the data d is further traced back, and the data value is in the same direction from the fluctuation range VB. When a predetermined number (four in this case) of a series of a plurality of data dos that continuously protrudes (in this case, the positive voltage side direction exceeding the upper value V10) is detected, these data dos It is determined that a boundary region between the time T11 and the stable discharge time T10 is formed. Of the series of data dos, the timing ts corresponding to the data dos whose data value is out of the fluctuation range first is detected as the discharge stable timing for dividing the initial time T11 and the stable discharge time T12.

  In other words, the initial time T11 is calculated by obtaining the time from the preset 5 seconds as the discharge time to the timing ts as the stable discharge time T10 and then subtracting the stable discharge time T10 from the 5 seconds. In the example shown in the present embodiment, since the test discharge is repeatedly executed five times, the longest time among the initial times T11 obtained for each test discharge is adopted, and this initial time T11 is further adopted. Is a constant multiple (the constant is appropriately determined by an empirical value (for example, 1.5 times)) and set as the discharge start determination time TA. Note that the number of times that the test discharge is performed can be arbitrarily set. If the discharge characteristics are stable, the test discharge may be performed only once.

  In the above configuration, the determination parameter setting unit 34 starts plasma discharge from the start of high-frequency power output by the high-frequency power supply unit 19 serving as plasma generation means, based on the potential change data stored in the potential change storage unit 33. The discharge start determination time TA set based on the time until the plasma discharge is stabilized later (initial time T11), and the presence or absence of discharge start after the high frequency power is output until the discharge start determination time TA elapses The discharge start determination threshold value 37 (upper threshold value V1, lower threshold value V2) used for determining the abnormal discharge determination threshold value 38 (upper threshold value V1, lower threshold value V2) and the abnormal discharge determination threshold value 38 (upper limit value) used as a threshold value for detecting abnormal discharge Processing for setting the threshold value V3 and the lower threshold value V4) is performed.

  That is, the determination parameter setting unit 34 indicates, from the potential change data acquired in the test discharge, a stable representative value indicating the magnitude of the fluctuation range VB in the potential change corresponding to the plasma discharge performed in a stable state by a statistical representative value. An upper value V10 and a lower value V12, which are state amplitude data, are detected. Based on these stable state amplitude data, a discharge start determination threshold 37 (upper threshold V1, lower threshold V2) and an abnormal discharge determination threshold 38 (upper threshold V3, lower threshold V4) are set. Further, the data of the potential change is traced retrospectively in time series, and the data value first protrudes from the fluctuation range VB out of a series of a plurality of data whose data values continuously protrude from the fluctuation range VB in the same direction. A timing ts corresponding to the data dos is detected as a discharge stabilization timing, and a discharge start determination time TA is set based on the discharge stabilization timing.

  In this way, when the determination parameter automatic setting processing is completed, the plasma processing is performed under the newly set processing conditions on the substrate 9 which is the actual processing target (plasma processing stage). ). In this plasma processing stage, the discharge state determination unit 35 executes the following discharge monitoring process. That is, the plasma discharge is normally started by comparing the potential change detected immediately after the high frequency power supply unit 19 outputs the high frequency power and before the discharge start determination time TA elapses with the discharge start determination threshold 37. It is determined whether or not (discharge start determination stage). And the process which determines the presence or absence of abnormal discharge is performed by comparing the electric potential change detected after discharge start determination time TA passed with the abnormal discharge determination threshold value 38 (discharge state determination step).

  As described above, in the plasma processing apparatus of the present invention, the test discharge is executed according to the processing conditions set at the time of performing the plasma processing, the potential change data corresponding to the processing conditions is acquired, and then the potential change is performed. Set the determination parameters such as the discharge start determination time, the discharge start determination threshold value, and the abnormal discharge determination threshold value based on the above data, and immediately after the high frequency power is output in the plasma processing execution stage until the discharge start determination time elapses Is compared with the discharge start determination threshold value to determine whether or not the plasma discharge has started normally, and the potential change detected after the discharge start determination time has elapsed is compared with the abnormal discharge determination threshold value. Thus, a plasma processing method of determining the presence or absence of abnormal discharge is adopted.

  This makes it possible to set the determination parameters appropriately and easily even when the user changes the plasma processing conditions according to the type of product to be produced or when the apparatus state changes with time, and the discharge detection sensor can set the discharge state. In the configuration for monitoring the discharge state, the discharge state can be properly detected.

  According to the plasma processing apparatus and the plasma processing method of the present invention, the determination parameter can be set appropriately and easily, and the discharge state can be properly detected in the configuration in which the discharge state is monitored by the discharge detection sensor. It has an effect and is useful in the field of performing plasma processing using a substrate or the like as a processing target.

2 Lid 3 Vacuum chamber 3a Processing chamber 5 Electrode 8 Guide member 9 Substrate 15 Vacuum gauge 16 Gas supply 17 Vacuum pump 18 Matching device 19 High frequency power supply 22 Probe electrode unit 22b Probe electrode 23 Discharge detection sensor

Claims (4)

A vacuum chamber that forms a processing chamber for containing a processing object; a vacuum exhaust unit that evacuates the processing chamber; a gas supply unit that supplies a plasma discharge generating gas into the processing chamber; and a plasma discharge in the processing chamber Plasma generating means for generating plasma discharge by applying high-frequency power to the generating gas, and control for controlling the vacuum exhaust section, the gas supply section, and the plasma generating means based on preset processing conditions And a dielectric member mounted on the vacuum chamber with the one surface facing the plasma discharge generated in the processing chamber, and the other member. A discharge detection sensor having at least a probe electrode disposed on the surface of the electrode, and induced in the probe electrode in response to a change in the plasma discharge A plasma processing apparatus having a plasma discharge monitoring section for outputting a determination result to the control unit together with the position by detecting the change to determine the state of the plasma discharge,
The control unit includes a test discharge execution unit that executes a test discharge for acquiring data of the potential change corresponding to the processing condition,
The plasma discharge monitoring unit stores a potential change data acquired by the test discharge, and a high frequency power output from the plasma generating unit based on the potential change data stored in the potential change storage unit. Discharge start determination time set based on the time from the start of the plasma discharge to the stabilization of the plasma discharge, between the output of the high frequency power and the elapse of the discharge start determination time A determination parameter setting unit for setting a discharge start determination threshold used for determining whether or not there is a discharge start and an abnormal discharge determination threshold used as a threshold for detecting abnormal discharge after the discharge start determination time has elapsed The potential detected immediately after the high-frequency power is output and before the discharge start determination time elapses Is compared with the discharge start determination threshold value to determine whether the plasma discharge has started normally, and the potential change detected after the discharge start determination time has elapsed is compared with the abnormal discharge determination threshold value. A plasma processing apparatus comprising a discharge state determination unit that determines whether there is abnormal discharge.   The determination parameter setting unit is a stable state indicating, by a statistical representative value, a magnitude of a fluctuation range in a potential change corresponding to a plasma discharge performed in a stable state, from potential change data acquired in the test discharge. Amplitude data is detected, the discharge start determination threshold and the abnormal discharge determination threshold are set based on the steady state amplitude data, and the potential change data is traced retrospectively in time series, so that the data value changes The timing corresponding to the data whose data value protrudes from the fluctuation range first is detected as the discharge stabilization timing among a series of a plurality of data that continuously protrudes in the same direction from the width, and based on the discharge stabilization timing, The plasma processing apparatus according to claim 1, wherein a discharge start determination time is set. A vacuum chamber that forms a processing chamber for containing a processing object; a vacuum exhaust unit that evacuates the processing chamber; a gas supply unit that supplies a plasma discharge generating gas into the processing chamber; and a plasma discharge in the processing chamber Plasma generating means for generating plasma discharge by applying high-frequency power to the generating gas, and control for controlling the vacuum exhaust section, the gas supply section, and the plasma generating means based on preset processing conditions And a dielectric member mounted on the vacuum chamber with the one surface facing the plasma discharge generated in the processing chamber, and the other member. A discharge detection sensor having at least a probe electrode disposed on the surface of the electrode, and induced in the probe electrode in response to a change in the plasma discharge A plasma processing method for performing plasma processing on the object to be processed by a plasma processing apparatus including a plasma discharge monitoring unit that detects a change in position and determines a state of the plasma discharge and outputs a determination result to the control unit. There,
A processing condition setting step for setting processing conditions of the plasma processing including processing pressure in the processing chamber, type of gas for generating plasma discharge, flow rate, and output of the high-frequency power, and data of the potential change corresponding to the processing conditions A potential change storage step of performing a test discharge for acquiring the voltage change and storing the potential change data obtained by the test discharge in the potential change storage unit;
From the potential change data stored in the potential change storage unit in the potential change storage step, the time from the start of the high frequency power output by the plasma generating means to the time when the plasma discharge is stabilized after the plasma discharge starts. A discharge start determination time set based on the discharge start determination threshold value used for determining whether or not to start a discharge from when the high frequency power is output until the discharge start determination time elapses, and the discharge start determination A determination parameter setting stage for setting an abnormal discharge determination threshold used as a threshold for detecting abnormal discharge after a lapse of time, and plasma processing for executing plasma processing on the processing object under the processing conditions Including stages,
In the plasma processing step, the plasma discharge is normally started by comparing the potential change detected immediately after the high-frequency power is output and before the discharge start determination time elapses with the discharge start determination threshold. A discharge start determination step for determining whether or not an abnormal discharge has occurred by comparing a potential change detected after the discharge start determination time has elapsed with the abnormal discharge determination threshold. A plasma processing method comprising:   In the determination parameter setting stage, from the potential change data acquired in the test discharge, a stable state indicating the magnitude of the fluctuation range in the potential change corresponding to the plasma discharge performed in a stable state by a statistical representative value Amplitude data is detected, the discharge start determination threshold and the abnormal discharge determination threshold are set based on the steady state amplitude data, and the potential change data is traced retrospectively in time series, so that the data value changes The timing corresponding to the data whose data value protrudes from the fluctuation range first is detected as the discharge stabilization timing among a series of a plurality of data that continuously protrudes in the same direction from the width, and based on the discharge stabilization timing, The plasma processing method according to claim 3, wherein a discharge start determination time is set.

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