JP6667343B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method for performing a plasma process on a substrate.

  In a manufacturing process of a flat panel display (FPD), a plasma process such as etching, sputtering, or CVD (chemical vapor deposition) is performed on a substrate to be processed.

  As a plasma processing apparatus for performing such plasma processing, for example, a pair of parallel plate electrodes (upper and lower electrodes) are arranged in a processing container, and a substrate to be processed is placed on a metal substrate mounting table functioning as a lower electrode. With the chamber placed in a vacuum state, a high-frequency electric power is applied to at least one of the electrodes to form a high-frequency electric field between the electrodes, and a plasma of a processing gas is formed by the high-frequency electric field on the substrate to be processed. A plasma processing is known to perform plasma processing.

  In such a plasma processing apparatus, a matching device having a matching circuit for matching the impedance of a load (plasma) to the impedance of the transmission line on the high-frequency power supply side is provided between the electrode and the high-frequency power supply. High-frequency transmission is performed efficiently by suppressing reflected waves. However, immediately after the application of the high-frequency power, the impedance matching by the matching device cannot be made in time, and a reflected wave from the plasma side to the high-frequency power supply is generated. Separately from this, after applying high frequency power and achieving sufficient matching, voltage non-uniformity occurs in the pattern on the substrate surface due to in-plane non-uniformity of the plasma, etc., and a reflected wave from the plasma side to the high-frequency power source is generated, This may cause an arc discharge (abnormal discharge) in the chamber, particularly in the surface of the substrate to be processed.

  If such an arc discharge continues, there is a possibility that the substrate to be processed may be damaged. Therefore, it is generally performed to detect the occurrence or the probability of such an arc discharge and cut off the supply of high-frequency power. I have.

  As a technique capable of accurately detecting the occurrence of such arc discharge, Patent Document 1 discloses a first time differentiating circuit for temporally differentiating a traveling wave voltage of high-frequency power toward a chamber, and returns from the chamber. A second time differentiating circuit for temporally differentiating the reflected wave voltage of the high-frequency power, and a value corresponding to the difference between the time differential value of the reflected wave voltage and the time differential value of the traveling wave voltage, and the calculated difference And a comparator that determines that an arc discharge has occurred in the processing chamber when the value corresponding to the predetermined value exceeds a predetermined threshold, and when the time derivative of the traveling wave voltage is negative, the value corresponding to the difference is smaller than the predetermined threshold. There is disclosed a diode having at least a diode for changing at least one of the time differential value of the reflected wave voltage and the time differential value of the traveling wave voltage so as to be smaller. Thus, when the time derivative of the traveling wave voltage is negative, at least the reflected wave voltage is reduced so that the value corresponding to the difference between the time derivative of the reflected wave voltage of the high-frequency power and the time derivative of the traveling wave voltage becomes smaller. Is changed, the occurrence of arc discharge can be detected accurately.

  On the other hand, as the plasma processing apparatus as described above, a high-frequency power for plasma generation is applied to the upper electrode or the lower electrode, and a bias power for drawing ions in the plasma to the substrate to be processed is applied to the lower electrode, and a bias is applied. A technique for suppressing arc discharge in the surface of a substrate to be processed by pulse-modulating the power for use is also used (for example, Patent Document 2). This technique reduces the effective bias power and Vdc by pulse-modulating the bias power. That is, the reduction in Vdc increases the margin of Vdc in-plane uniformity and suppresses arc discharge in the surface of the substrate to be processed.

JP 2014-165637 A JP 2014-179598 A

  By the way, although the technique of pulse-modulating the bias power described in Patent Document 2 can suppress the arc discharge in the surface of the substrate to be processed, it does not mean that the arc discharge does not occur. For this reason, it is also required to detect the occurrence or probability of arc discharge even in the technique of pulse-modulating the bias power.

  Therefore, it is conceivable to apply a technique for detecting arc discharge as described in Patent Document 1 also in the case of pulse modulation of bias power. In this case, a reflected wave generated for each pulse of bias power is generated. It is detected as an arc discharge, and the arc discharge cannot be effectively detected. If the arc discharge cannot be detected as described above, the arc discharge cannot be stopped when the arc discharge occurs in the surface of the substrate to be processed, and when the substrate is transported after the processing, the substrate is damaged by the arc discharge. It can also cause cracking.

  Therefore, the present invention provides a plasma processing apparatus and a plasma processing method capable of detecting the probability of arc discharge occurrence or the actual occurrence of arc discharge even when pulse power of bias power is modulated. Make it an issue.

In order to solve the above-described problems, a first aspect of the present invention is a plasma processing apparatus that performs a predetermined plasma process on a substrate to be processed, the processing container accommodating the substrate to be processed, and A gas supply unit for supplying a processing gas, an electrode disposed in the processing container, a high-frequency power supply unit for supplying pulse-modulated high-frequency power to the electrode, and a high-frequency power supply unit from the processing container. A reflected wave power measurement unit that measures the reflected wave power to be returned at a predetermined cycle, and a threshold of the reflected wave power is set, and when the value of the reflected wave power measured by the reflected wave power measurement unit exceeds the threshold, A determination unit for determining that arc discharge is likely to occur in the processing container or that arc discharge has actually occurred , wherein the reflected wave power gradually increases, and the pulse-modulated high frequency Electric power And pulse period and the measurement period different et allowed in the reflected wave power measuring section, wherein the measurement timing of the reflected wave power measuring unit, the reflection generated every pulse of the pulse-modulated high-frequency power is not generated timing And a plasma processing apparatus characterized in that:

According to a second aspect of the present invention, there is provided a plasma processing apparatus for performing a predetermined plasma process on a substrate to be processed, comprising: a processing container accommodating the substrate to be processed; and a gas supply for supplying a processing gas into the processing container. A plasma generating means for generating plasma in the processing chamber; a substrate mounting table for mounting a substrate disposed in the processing chamber; and a high-frequency power for pulse-modulated bias on the substrate mounting table. A high-frequency power supply unit that supplies the reflected-wave power, a reflected-wave power measuring unit that measures the reflected-wave power returning from the processing container toward the high-frequency power unit at a predetermined cycle, and a threshold value of the reflected-wave power is set. If the value of the reflected wave power measured by the unit exceeds the threshold, there is a probability that arc discharge occurs in the processing container, or comprising a determination unit that determines that arc discharge has actually occurred , Said Reflected wave power are those gradually increased, and the pulse period of the high frequency power the pulse-modulated, said measurement period different et allowed in the reflected wave power measuring unit, the measuring timing of the reflected wave power measuring unit, A plasma processing apparatus is provided, wherein the timing is set to a timing at which no reflection occurs for each pulse of the pulse-modulated high-frequency power .

  In the second aspect, the plasma generation means may include an upper electrode provided to face the substrate mounting table, and the upper electrode or the substrate mounting table functioning as a lower electrode. A high-frequency power supply for generating high-frequency power may be provided, and a high-frequency electric field may be formed between the substrate mounting table functioning as the upper electrode and the lower electrode to generate capacitively coupled plasma.

The Te first and second aspects smell, before Symbol further comprising a threshold setting unit that sets the threshold of the determination unit, the threshold setting unit, the when changing the time of starting the supply of high frequency power, or the output The threshold may be set to a relatively high value, and the threshold may be set to a relatively low value after the supply of the high-frequency power is stabilized.

The determining unit has a counter unit that counts the number of times that the reflected wave power exceeds the threshold, and when the count value of the counter unit exceeds a predetermined value, the determining unit is It can be determined that there is a probability that an arc discharge will occur in the processing vessel or that an arc discharge has actually occurred. When the reflected wave power does not exceed a predetermined value, the counter may return the count of the counter to zero.

  A stop control unit that outputs a signal to stop high-frequency power or stop the apparatus when the determination unit determines that arc discharge is likely to occur in the processing container, or when it is determined that arc discharge has actually occurred. May be further provided. The reflected wave power measurement unit may have a variable measurement cycle.

According to a third aspect of the present invention, there is provided a processing container accommodating a substrate to be processed, a gas supply unit for supplying a processing gas into the processing container, an electrode disposed in the processing container, and a pulse applied to the electrode. A plasma processing method for performing plasma processing by a plasma processing apparatus having a high-frequency power supply unit that supplies modulated high-frequency power, wherein a reflected wave power returning from the processing container toward the high-frequency power supply unit is measured at a predetermined cycle. , when the value of said measured reflected wave power exceeds a predetermined threshold value, there is a probability that the arc discharge in the processing chamber is generated, or actually determine the constant arc discharge is generated, the reflected wave power is intended gradually increased, and the pulse period of the high frequency power the pulse-modulated, the at different measurement periods of the reflected wave power, the measurement timing of the reflected wave power, varying the pulse To provide a plasma processing method characterized in that reflections occurring every high-frequency power pulses is set to a timing that does not occur.

According to a fourth aspect of the present invention, there is provided a processing container for accommodating a substrate to be processed, a gas supply unit for supplying a processing gas into the processing container, a plasma generating unit for generating plasma in the processing container, Plasma processing in which plasma processing is performed by a plasma processing apparatus having a substrate mounting table for mounting a substrate disposed in a container and a high-frequency power supply unit for supplying high-frequency power for pulse-modulated bias to the substrate mounting table A method, wherein the reflected wave power returning from the processing container toward the high-frequency power supply unit is measured at a predetermined cycle, and when the measured value of the reflected wave power exceeds a predetermined threshold, the inside of the processing container in there is likely to arc discharge occurs, or indeed determines that an arc discharge is generated, the reflected power are those gradually increased, the pulse-modulated high-frequency power pulse Features and period, said at different measurement periods of the reflected wave power, said measuring timing of the reflected wave power, reflection generated every pulse of the pulse-modulated high-frequency power is set to a timing that does not occur And a plasma processing method.

The Te third and fourth aspects odor, high frequency power at the start of the supply of, or is set to a relatively high value the threshold when changing the output, the threshold after the supply of the high-frequency power is stable Can be set to a relatively low value.

  Count the number of times that the reflected wave power exceeds the threshold, and when the count value exceeds a predetermined value, there is a probability that arc discharge will occur in the processing container, or arc discharge actually occurs. Is determined to have occurred. If the reflected wave power does not exceed a predetermined value, the count value can be set to zero.

  When it is determined that arc discharge is likely to occur in the processing container or that arc discharge has actually occurred, a signal for stopping high-frequency power or stopping the apparatus may be output. The measurement cycle of the reflected wave power may be variable.

  According to the present invention, since the pulse cycle of the pulse-modulated high-frequency power and the measurement cycle in the reflected wave power measurement unit are different, when measuring the reflected wave power that is an index of the occurrence of arc discharge, the bias It is not affected by the reflected wave due to the power pulse. Therefore, even when the bias power is pulse-modulated, the probability of occurrence of an arc discharge or the actual occurrence of an arc discharge can be detected by the reflected wave power.

FIG. 1 is a sectional view showing a plasma etching apparatus according to one embodiment of the present invention. FIG. 3 is a diagram for explaining the concept of a control unit in the plasma etching apparatus according to one embodiment of the present invention. FIG. 2 is a block diagram for explaining a configuration of a control unit in the plasma etching apparatus according to one embodiment of the present invention. FIG. 2 is a block diagram illustrating a main configuration of a main control unit of a control unit in the plasma etching apparatus according to one embodiment of the present invention. FIG. 4 is a diagram showing a state in which the probability of arc discharge is actually detected in the plasma etching apparatus according to one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a sectional view showing a plasma etching apparatus according to one embodiment of the present invention.

  As shown in FIG. 1, the plasma etching apparatus 1 is configured as a capacitively coupled plasma processing apparatus that performs a plasma process, for example, a plasma etching process, on a glass substrate (hereinafter simply referred to as “substrate”) G for FPD. Have been. Examples of the FPD include a liquid crystal display (LCD), an electroluminescence (Electro Luminescence; EL) display, a plasma display panel (PDP), and the like.

  The plasma etching apparatus 1 includes a chamber 2 as a processing container that stores a substrate G that is a substrate to be processed. The chamber 2 is made of, for example, aluminum whose surface is anodized (anodized), and is formed in a square tube shape corresponding to the shape of the substrate G.

  A substrate mounting table 3 functioning as a lower electrode is provided at the bottom of the chamber 2 via an insulating member 4 made of an insulating material. The substrate mounting table 3 includes a base member 5 made of metal, for example, aluminum, an insulating shield ring 7 provided around an upper portion of the base member 5, and an insulating ring 8 provided around a side surface of the base member 5. And Although not shown, an electrostatic chuck for electrostatically adsorbing the substrate G is provided on the surface of the substrate mounting table 3, and elevating pins used for transporting the substrate G are inserted into the substrate mounting table 3. I have. Although not shown, a temperature control mechanism for controlling the temperature of the substrate G and a temperature sensor are provided in the substrate mounting table 3.

  A shower head 20 that supplies a processing gas into the chamber 2 and functions as an upper electrode is provided above the chamber 2 so as to face the substrate mounting table 3. The shower head 20 has a gas diffusion space 21 for diffusing the processing gas therein, and a plurality of discharge holes 22 for discharging the processing gas on a surface facing the substrate mounting table 3.

A gas inlet 24 is provided on the upper surface of the shower head 20, and a processing gas supply pipe 25 is connected to the gas inlet 24. The processing gas supply pipe 25 is connected to a processing gas supply source 28. I have. Further, an opening / closing valve 26 and a mass flow controller 27 are interposed in the processing gas supply pipe 25. Actually, a plurality of processing gas supply sources 28 are provided in accordance with the number of processing gases, and processing gas supply pipes 25 extend from the respective processing gas supply sources 28. The processing gas supply source 28 supplies a processing gas for plasma etching. As a processing gas, a gas generally used in this field, such as a halogen-based gas, an O ₂ gas, and an Ar gas, can be used.

  A plurality of exhaust ports 29 (only two are shown) are formed at the edges or corners of the bottom wall of the chamber 2, and each exhaust port 29 is provided with an exhaust unit 30. The exhaust unit 30 includes an exhaust pipe 31 connected to the exhaust port 29, an automatic pressure control valve (APC) 32 that controls the pressure in the chamber 2 by adjusting the opening of the exhaust pipe 31, A vacuum pump 33 for exhausting the gas through the exhaust pipe 31. Then, the inside of the chamber 2 is evacuated by the vacuum pump 33, and during the plasma etching processing, the opening degree of the automatic pressure control valve (APC) 32 is adjusted to set and maintain the inside of the chamber 2 at a predetermined vacuum atmosphere.

  A loading / unloading port 35 for loading / unloading the substrate G and a gate valve 36 for opening / closing the loading / unloading port 35 are provided on one side wall of the chamber 2.

  A transmission line 41 for supplying high-frequency power is connected to the shower head 20 functioning as an upper electrode, and a matching unit 42 and a first high-frequency power supply unit 43 are connected to the transmission line 41. The first high-frequency power supply unit 43 supplies the showerhead 20 with a high-frequency power for generating plasma having a frequency in the range of 4 to 100 MHz, for example, 13.56 MHz. Thus, a high-frequency electric field is generated between the shower head 20 functioning as an upper electrode and the substrate mounting table 3 functioning as a lower electrode, and a capacitively-coupled plasma is generated therebetween.

  A transmission line 51 for supplying high frequency power is connected to the base material 5 of the substrate mounting table 3. The transmission line 51 extends to the outside of the chamber 2 through a hole 2 a provided at the bottom of the chamber 2, and a matching device 52 and a second high-frequency power supply unit 53 are connected to the transmission line 51. Then, a high-frequency power of a frequency in the range of 0.4 to 6 MHz, for example, 3.2 MHz, is supplied from the second high-frequency power supply unit 53 to the substrate mounting table 3 by a high-frequency power for bias for drawing ions into the substrate G (bias). Power). The second high frequency power supply unit 53 has a built-in pulse modulation unit, and pulse-modulates the output bias power in a duty ratio range of 5 to 95%. The transmission line 51 passes through a hole 2a provided at the bottom of the chamber 2 and

  The matching unit 42 has a matching circuit combining a capacitor and a coil, one end of which is connected to the first high-frequency power supply unit 43 via the transmission line 41 and the other end of which is connected to the shower head 20. The matching device 52 includes a matching circuit having a combination of a capacitor and a coil, one end of which is connected to the second high frequency power supply unit 53 via the transmission line 51 and the other end of which is connected to the base material 5 of the substrate mounting table 3. Have. These matching circuits have a function of matching the impedance of the load (plasma) with the impedance of the corresponding transmission line on the power supply unit side, and suppressing the reflected wave returning from the chamber 2 to the power supply unit.

  The transmission line 41 between the first high-frequency power supply unit 43 and the matching unit 42 is connected to a reflected-wave power measurement unit 44 that measures the reflected-wave power returning from the chamber 2 to the first high-frequency power supply unit 43. The transmission line 51 between the second high frequency power supply unit 53 and the matching unit 52 is connected to a reflected wave power measurement unit 54 for measuring the reflected wave power returning from the chamber 2 to the second high frequency power supply unit 53. The reflected wave power measuring section 54 samples the reflected wave power at a predetermined cycle different from the pulse cycle of the high frequency power of the second high frequency power supply section 53. At this time, it is preferable that the reflected wave power measurement unit 54 change the sampling cycle.

  The plasma etching apparatus 1 further includes a control unit 100. As shown in FIG. 2, the control unit 100 includes components constituting the plasma etching apparatus 1, for example, a first high-frequency power supply unit 43, a second high-frequency power supply unit 53, a vacuum pump 33, and an automatic pressure control valve (APC). 32, an opening / closing valve 26, a mass flow controller 27, a temperature control mechanism, and the like are connected via an I / O port and the like, and the control unit 100 controls them.

  As shown in FIG. 3, the control unit 100 includes a main control unit 101, an input device 102 such as a keyboard, an output device 103 such as a printer, a display device 104, a storage device 105, an external interface 106, Are connected to each other. The main control unit 101 has a CPU 108, a RAM 109, and a ROM 110. The storage device 105 stores information, and reads information stored in a computer-readable storage medium 111. Although the storage medium 111 is not particularly limited, for example, a hard disk, an optical disk, a flash memory, or the like is used. In the main control unit 101 of the control unit 100, the CPU 108 controls the plasma etching apparatus 1 by executing a program stored in the ROM 110 or the storage device 105. In addition, by using a storage medium 111 in which a processing recipe is stored, the CPU 108 performs plasma processing on the substrate G in the plasma etching apparatus 1 which is the plasma processing apparatus of the present embodiment based on the processing recipe called from the storage medium. The processing is executed.

  FIG. 4 is a block diagram illustrating a main configuration of the main control unit 101 of the control unit 100 according to the present embodiment. In the present embodiment, the main control unit 101 includes a determination unit 121, a threshold setting unit 122, and a stop control unit 124, in addition to a control area for causing each component to execute predetermined control.

  The determination unit 121 compares the reflected wave power measured by the reflected wave power measurement units 44 and 54 with a predetermined threshold at the timing when the respective reflected wave powers are measured, and determines whether the reflected wave power exceeds the predetermined threshold. For example, it is determined that the condition for generating an arc discharge in the chamber 2 is satisfied. That is, since the arc discharge in the chamber 2 is generated when the reflected wave power is increased, a threshold value is set in advance, and when the threshold value is exceeded, it is determined that the arc discharge is likely to occur, and the high frequency power is stopped. Or shut down the device. The determining unit 121 may determine that an arc discharge has actually occurred. The determination unit 121 has a counter unit 123.

  The counter unit 123 counts the number of times that the determination unit 121 determines that the reflected wave power measured by the reflected wave power measurement unit 54 exceeds the threshold, and the count exceeds a predetermined number of times (set value). At this time, a determination signal that has been determined to exceed the threshold of the determination unit 121 is sent to the stop control unit 124. For example, when the set value of the counter unit 123 is set to 1, when the determination unit 121 counts twice that the reflected wave power has exceeded the threshold, the determination unit 121 sends a determination signal to the stop control unit 124.

The reason for using the counter unit 123 in this way is as follows.
The reflected wave power measuring section 54 samples the reflected wave power at a predetermined cycle different from the pulse cycle of the high frequency power of the second high frequency power supply section 53 so as not to overlap the reflected wave caused by the pulse. If they accidentally overlap with each other, there is a possibility that the high-frequency power or the device may be stopped accidentally. However, such a case can be avoided by counting the number of times that the reflected wave power has exceeded the threshold value and issuing the determination signal after the number of times has exceeded the set value. At this time, it is preferable to send a determination signal to the stop control unit 124 when the counter unit 123 counts the determination that the threshold value has been exceeded twice or more consecutively.

  If the reflected wave power does not exceed the threshold, the count of the counter unit 123 may be returned to zero. Further, since the first high-frequency power supply unit 43 is not pulse-modulated, the above-described problem does not occur in the reflected power measurement unit 44. Therefore, when an arc discharge is detected based on the reflected wave power measurement unit 44, the set value of the corresponding counter unit 123 is set to 0, and when the determination that the threshold value has been exceeded has been performed even once, the determination signal is output. May be sent to the stop control unit 124.

  The threshold setting unit 122 sets a threshold of the reflected wave power in the determination unit 121. As the threshold, at least two types of thresholds, a relatively high level threshold and a relatively low level threshold, can be set. Further, the threshold setting unit 122 sets the threshold to a relatively high level at the timing of starting the supply of the high frequency from the first high frequency power supply unit 43 or the second high frequency power supply unit 53 or the timing of changing the output. Set. Then, after the supply of the high-frequency power from the second high-frequency power supply unit 53 is stabilized, that is, when the impedance matching by the matching unit 52 is completed and the reflected wave power is stabilized at a low value, the threshold level is relatively low. Switch to level. The relatively high level threshold is used to prevent the determination unit 121 from determining that the condition for generating an arc discharge in the chamber 2 has been reached due to a reflected wave inevitably generated when the plasma is started. . The relatively low threshold value is preferably as low as possible (for example, 5% or less of the rated power value, preferably 2 to 5) in order to promptly deal with reflected waves that may lead to arc discharge. % Is preferred).

  Upon receiving the signal from the determination unit 121, the stop control unit 124 outputs a high-frequency power stop signal or a device stop signal to stop the first high-frequency power supply unit 43 and the second high-frequency power supply unit 53, or The etching process 1 is stopped.

  Note that the reflected wave power measuring unit 44 for measuring the reflected wave power to the first high frequency power supply unit 43 is not provided, and only the reflected wave power measuring unit 54 is provided to measure only the reflected wave power to the second high frequency power supply unit 53. You may make it.

Next, a processing operation in the plasma etching apparatus 1 configured as described above will be described. The following processing operation is performed under the control of the control unit 100.
First, the inside of the chamber 2 is evacuated to a predetermined pressure by the exhaust unit 30, the gate valve 36 is opened, the substrate G is carried in from the carry-in / out port 35 by carrying means (not shown), and the lifter pins (not shown) are lifted. The substrate G is received thereon, and the lifter pins are lowered to place the substrate G on the substrate mounting table 3. After retracting the transfer means from the chamber 2, the gate valve 36 is closed.

  In this state, the temperature of the substrate mounting table 3 is controlled by a temperature control mechanism, the temperature of the substrate G is controlled to a predetermined temperature, and the pressure inside the chamber 2 is controlled by an automatic pressure control valve (APC) 32 while the vacuum pump 33 exhausts the gas. Is adjusted to a predetermined degree of vacuum, the flow rate is adjusted from the processing gas supply source 28 by the mass flow controller 27, and the processing gas is supplied into the chamber 2 through the processing gas supply pipe 25 and the shower head 20.

  Then, high frequency (RF) power for plasma generation is applied from the first high frequency power supply unit 43 to the shower head 20 as the upper electrode via the matching unit 42. As a result, a high-frequency electric field is generated between the substrate mounting table 3 as the lower electrode and the shower head 20 as the upper electrode, so that the processing gas in the chamber 2 is turned into plasma, and the etching of the substrate G proceeds.

  On the other hand, during such plasma etching, bias power is supplied from the second high-frequency power supply unit 53 to the substrate mounting table 3 (base material 5) as a lower electrode via the matching unit 52. Thereby, ions in the plasma are drawn into the substrate G, and plasma etching with high anisotropy is realized. At this time, the output bias power is pulse-modulated.

  After performing the plasma etching process for a predetermined time, the supply of the high-frequency power from the first high-frequency power supply unit 43 and the second high-frequency power supply unit 53 and the supply of the processing gas are stopped, and the chamber 2 is evacuated and the chamber 2 is evacuated. Is purged with a purge gas. Then, the gate valve 36 is opened, and the substrate G is carried out of the carry-in / out port 35 by a carrying means (not shown). Thus, the plasma etching process for one substrate G is completed.

  In such plasma etching, impedance matching can no longer be achieved by the matching unit due to changes in conditions during processing, etc., and reflected waves from the plasma side to the high frequency power supply increase, resulting in arc discharge in the chamber. There is. If the arc discharge continues, the substrate G may be damaged, and the substrate G may be broken after the processing. Therefore, it is necessary to detect the occurrence of the arc discharge or its probability by measuring the reflected wave power. The technique of Patent Document 1 is known.

  On the other hand, in the present embodiment, the bias power is pulse-modulated. As a result, the effective bias power can be reduced and Vdc can be reduced, so that the margin of Vdc in-plane uniformity is widened and arc discharge such as ESD can be suppressed.

  However, in the technique of the above-mentioned Patent Document 1, since an arc discharge which occurs steeply in a short time is detected, the sampling cycle is usually about 2 μsec, and when the bias power is pulse-modulated, every pulse of the bias power is applied. The erroneous recognition of the reflected wave generated as the arc discharge is not possible, and the arc discharge cannot be effectively detected.

  In this embodiment, based on the fact that the arc discharge in the plane of the substrate is caused by the gradually rising reflected wave power, and such a reflected wave power continuously exceeds the threshold value, which leads to cracking of the substrate. The focus is on detecting a predetermined value before the value of the reflected wave power reaches a value that causes such arc discharge in the substrate surface, or detecting that the value has reached such a value.

  That is, in order to detect such a gradually rising reflected wave power, it is not necessary to measure the reflected wave power at high speed as assumed in Patent Document 1, and it is generated for each pulse of the bias power. When no reflected wave is generated, it is sufficient to detect the reflected wave power going to the high frequency power supply unit. Therefore, in the present embodiment, when determining the value of the reflected wave power, the pulse cycle of the pulse-modulated bias power of the second high-frequency power supply unit 53 and the sampling cycle of the reflected wave power in the reflected wave power measurement unit 54 are determined. (Measurement cycle).

  Accordingly, when measuring the reflected wave power serving as an index of the occurrence of arc discharge, there is no influence of the reflected wave due to the bias power pulse. Therefore, even when the bias power is pulse-modulated, the probability of occurrence of arc discharge or the actual occurrence of arc discharge can be detected by the reflected wave power.

  At this time, the cycle of the bias power pulse is changed according to the measurement cycle of the reflected power measuring section 54, or an appropriate sampling cycle is selected as the reflected power measuring section 54 according to the pulse modulation cycle. This makes it possible to adjust the pulse cycle of the bias power and the sampling cycle of the reflected power, but it is not necessary to replace the reflected power measuring section 54 by making the sampling cycle of the reflected power measuring section 54 variable. And the setting width of the bias power pulse can be widened.

  In the present embodiment, the determination unit 121 determines whether or not the reflected wave power exceeds the threshold in a predetermined cycle, and the determination unit 121 determines the number of times that the reflected wave power is determined to exceed the threshold by the built-in counter 123. Counting, when the count value exceeds a predetermined value, sends a determination signal indicating that the reflected wave power exceeds the threshold value to the stop control unit 124, and the stop control unit 124 receiving the signal stops the high frequency power or the device Output a stop signal for

  The determination by the determination unit 121 compares the reflected wave power measured by the reflected wave power measurement units 44 and 54 with a predetermined threshold value, and determines whether the reflected wave power exceeds a predetermined threshold value. The threshold value at this time is set by the threshold value setting unit 122. Since the threshold value setting unit 122 can set a plurality of threshold values, the reflected wave is unstable, the timing to start supplying high frequency, or the output At the timing of changing the threshold value, the threshold level is set to a high level, and when the reflected wave power is stabilized at a low value, the threshold level can be switched to a relatively low level. This prevents an erroneous determination that the condition for generating an arc discharge due to an inevitably generated reflected wave when the plasma is started is met, and sets the threshold value as low as possible after the reflected wave power is stabilized at a low value. By lowering it, it is possible to respond before the arc discharge actually occurs.

  Further, the counter unit 123 counts the number of times that the determination unit 121 determines that the reflected wave power measured by the reflected wave power measurement unit 54 exceeds the threshold, and when the count exceeds the set number of times, the A determination signal indicating that the wave power has exceeded the threshold value is sent to the stop control unit 124, and the stop control unit 124 receives the signal and outputs a high-frequency power or a stop signal for stopping the apparatus. When the sampling periods of the wave power are accidentally overlapped, it is possible to prevent the high-frequency power or the device from being stopped by mistake. In this case, when the determination that the threshold value is exceeded is continuously performed twice or more, a signal is sent to the stop control unit 124 to more reliably prevent the high-frequency power or the device from being stopped by mistake. Can be.

  In addition, when the determination unit 121 determines that the reflected wave power exceeds the threshold, the stop control unit 124 outputs a high-frequency power or a stop signal for stopping the apparatus. It is possible to reliably stop the high-frequency power or the device itself before cracking of the substrate occurs, and it is possible to more reliably prevent cracking of the substrate.

Next, a state in which the probability of arc discharge is actually detected in the plasma processing apparatus of the present embodiment will be described with reference to FIG.
In FIG. 5, the first high-frequency power supply for plasma generation has a continuous output, and the second high-frequency power supply for bias has been pulse-modulated, and has a period of 220 μsec and a duty ratio of 90%. The reflected wave power increases in the beginning and stabilizes in the middle. Correspondingly, the threshold value is set to a high value at the initial stage, and is set to a low value after the reflected wave power becomes low and stable. A large reflected wave is generated at the rise of the pulse of the second high-frequency power supply unit, and in Patent Document 1, this is detected. On the other hand, in this example, since the sampling cycle of the reflected power is set to 200 μsec, the pulse cycle of the bias power and the sampling cycle of the reflected power are different, and the influence of the reflected wave due to the bias power pulse is different. The reflected wave power can be measured without receiving it. Further, in this example, the reflected wave power gradually increases, and the reflected wave power exceeds the threshold value. If left as it is, an arc discharge occurs in the substrate surface, and the sustained arc discharge may lead to cracking of the substrate. There is. Therefore, in the present example, the apparatus is stopped at the time when the reflected wave power exceeds the threshold value twice consecutively. As a result, arc discharge was not generated in the plane of the substrate, and cracking of the substrate could be prevented.

<Other applications>
The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the concept of the present invention. For example, in the above embodiment, the case where the present invention is applied to the plasma etching apparatus has been described. However, the present invention is not limited to this, and can be applied to other plasma processing apparatuses such as plasma ashing and plasma CVD.

Further, in the above embodiment, the case where the high frequency power for plasma generation is applied to the upper electrode and the high frequency power for bias is applied to the lower electrode has been described. Any high-frequency power for bias and plasma generation may be applied to the lower electrode. In addition, as long as it supplies a pulse-modulated bias high frequency power to the substrate mounting table, the plasma generating means is not limited to the capacitively coupled plasma as described in the above embodiment, but may be another plasma such as an inductively coupled plasma. Can be applied to a plasma processing apparatus having a plasma generating means for generating the plasma.
Absent.

  Furthermore, the present invention can be applied to a case where a pulse-modulated power is used as the high-frequency power supply unit, and is not limited to a case where the bias high-frequency power is pulse-modulated.

  Further, in the above-described embodiment, an example in which the present invention is applied to a glass substrate for an FPD has been described. However, it is needless to say that the present invention is not limited to a glass substrate for an FPD, but may be applied to other substrates such as a semiconductor substrate. .

1: Plasma etching equipment (plasma processing equipment)
2; chamber (processing vessel)
3: substrate mounting table 5; base material 20; shower head 25: processing gas supply pipe 28: processing gas supply source 30; exhaust unit 42, 52; matching unit 43; first high frequency power supply unit 44, 54; reflected wave power measurement Unit 53; second high-frequency power supply unit 100; control unit 101; main control unit 121; determination unit 122; threshold setting unit 123; counter unit 124;

Claims (15)

A plasma processing apparatus for performing a predetermined plasma processing on the substrate to be processed,
A processing container for storing a substrate to be processed,
A gas supply unit for supplying a processing gas into the processing container,
An electrode disposed in the processing container,
A high-frequency power supply for supplying pulse-modulated high-frequency power to the electrode;
A reflected wave power measurement unit that measures the reflected wave power returning from the processing container toward the high-frequency power supply unit at a predetermined cycle,
A threshold value of the reflected wave power is set, and when the value of the reflected wave power measured by the reflected wave power measurement unit exceeds the threshold value, there is a possibility that arc discharge occurs in the processing container, or actually A determination unit that determines that an arc discharge has occurred , and
The reflected wave power gradually increases,
And the pulse period of the high frequency power the pulse-modulated, said measurement period different et allowed in the reflected wave power measuring unit, generates a measurement timing of the reflected wave power measuring unit for each pulse of the pulse-modulated high-frequency power The plasma processing apparatus is set at a timing at which no reflection occurs . A plasma processing apparatus for performing a predetermined plasma processing on the substrate to be processed,
A processing container for storing a substrate to be processed,
A gas supply unit for supplying a processing gas into the processing container,
Plasma generation means for generating plasma in the processing container,
A substrate mounting table for mounting a substrate disposed in the processing container,
A high-frequency power supply unit for supplying high-frequency power for pulse-modulated bias to the substrate mounting table;
A reflected wave power measurement unit that measures the reflected wave power returning from the processing container toward the high-frequency power supply unit at a predetermined cycle;
The threshold value of the reflected wave power is set, and when the value of the reflected wave power measured by the reflected wave power measurement unit exceeds the threshold value, there is a possibility that arc discharge occurs in the processing container, or actually A determination unit that determines that an arc discharge has occurred , and
The reflected wave power gradually increases,
And the pulse period of the high frequency power the pulse-modulated, said measurement period different et allowed in the reflected wave power measuring unit, generates a measurement timing of the reflected wave power measuring unit for each pulse of the pulse-modulated high-frequency power The plasma processing apparatus is set at a timing when no reflection occurs .   The plasma generation means includes a plasma generation unit that supplies high-frequency power for plasma generation to an upper electrode provided to face the substrate mounting table, and to the substrate mounting table functioning as the upper electrode or the lower electrode. 3. The plasma processing apparatus according to claim 2, further comprising: a high-frequency power supply unit for generating a high-frequency electric field between the substrate mounting table functioning as the upper electrode and the lower electrode to generate capacitively-coupled plasma. . The apparatus further includes a threshold setting section that sets a threshold of the determination section, wherein the threshold setting section sets the threshold to a relatively high value when starting supply of high-frequency power or when changing output, The plasma processing apparatus according to any one of claims 1 to 3 , wherein the threshold is set to a relatively low value after power supply is stabilized. The determining unit has a counter unit that counts the number of times that the reflected wave power exceeds the threshold, and when the count value of the counter unit exceeds a predetermined value, the determining unit is The plasma processing apparatus according to any one of claims 1 to 4, wherein it is determined that an arc discharge is likely to occur in the processing container, or it is determined that an arc discharge has actually occurred. The plasma processing apparatus according to claim 5 , wherein the counter unit returns the count number of the counter unit to 0 when the reflected wave power does not exceed a predetermined value. A stop control unit that outputs a signal to stop high-frequency power or stop the apparatus when the determination unit determines that arc discharge is likely to occur in the processing container, or when it is determined that arc discharge has actually occurred. The plasma processing apparatus according to any one of claims 1 to 6 , further comprising: The plasma processing apparatus according to any one of claims 1 to 7 , wherein the reflected wave power measurement unit has a variable measurement cycle. A processing container for storing a substrate to be processed,
A gas supply unit for supplying a processing gas into the processing container,
An electrode disposed in the processing container,
A plasma processing method for performing plasma processing on the electrode by a plasma processing apparatus having a high-frequency power supply unit that supplies a pulse-modulated high-frequency power,
The reflected wave power returning from the processing container toward the high-frequency power supply unit is measured at a predetermined cycle, and when the measured value of the reflected wave power exceeds a predetermined threshold , an arc discharge occurs in the processing container. there is a probability that, or actually determine the constant arc discharge is generated,
The reflected wave power gradually increases,
By making the pulse cycle of the pulse-modulated high-frequency power different from the measurement cycle of the reflected-wave power, a reflection occurs in which the measurement timing of the reflected-wave power is generated for each pulse of the pulse-modulated high-frequency power. A plasma processing method characterized in that the timing is not set . A processing container for storing a substrate to be processed,
A gas supply unit for supplying a processing gas into the processing container,
Plasma generation means for generating plasma in the processing container,
A substrate mounting table for mounting a substrate disposed in the processing container,
A plasma processing method for performing plasma processing by a plasma processing apparatus having a high-frequency power supply unit that supplies high-frequency power for pulse-modulated bias to the substrate mounting table,
The reflected wave power returning from the processing container toward the high-frequency power supply unit is measured at a predetermined cycle, and when the measured value of the reflected wave power exceeds a predetermined threshold , an arc discharge occurs in the processing container. It is determined that there is a possibility that an arc discharge has actually occurred,
The reflected wave power gradually increases,
By making the pulse cycle of the pulse-modulated high-frequency power different from the measurement cycle of the reflected-wave power, a reflection occurs in which the measurement timing of the reflected-wave power is generated for each pulse of the pulse-modulated high-frequency power. A plasma processing method characterized in that the timing is not set . When the supply of high-frequency power is started or when the output is changed, the threshold is set to a relatively high value, and after the supply of high-frequency power is stabilized, the threshold is set to a relatively low value. The plasma processing method according to claim 9 or 10 , wherein Count the number of times that the reflected wave power exceeds the threshold, and when the count value exceeds a predetermined value, there is a probability that arc discharge will occur in the processing container, or arc discharge actually occurs. The method according to any one of claims 9 to 11, wherein it is determined that the generation of the plasma has occurred.   13. The plasma processing method according to claim 12, wherein the count value is set to 0 when the reflected wave power does not exceed a predetermined value. When there is a probability that the arc discharge is generated in the processing vessel, or actually arcing is determined to have occurred, claim and outputs a signal for stopping the stop to or device high-frequency power 9 The plasma processing method according to any one of claims 1 to 13 . The plasma processing method according to claim 9 in any one of claims 14, wherein the measuring period of the reflected wave power is variable.

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