JP2017183030A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus and a plasma processing method that can detect a probability of arc discharge generation or actual arc discharge generation even when pulse modulation on electric power for bias is performed.SOLUTION: A plasma processing apparatus 1 which performs predetermined plasma processing on a substrate G comprises: a processing container 2 which contains the substrate G; a gas supply part 28 which supplies a processing gas into the processing container 2; an electrode 3 which is arranged in the processing container 2; a high-frequency power source part 53 which supplies pulse-modulated high-frequency electric power to the electrode 3; a reflected wave electric power measurement part 54 which measures reflected wave electric power returning from the processing container 2 to the high-frequency power source part 53 at a predetermined period; and a determination part 121 which determines that there is a probability that an arc discharge is generated in the processing container 2 or that an arc discharge has been actually generated when the reflected wave electric power measured by the reflected wave electric power measurement part 54 meets a predetermined condition, a pulse period of the pulse-modulated high-frequency electric power being different from a measurement period of the reflected wave electric power measurement part 54.SELECTED DRAWING: Figure 1

Description

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

  In the manufacturing process of a flat panel display (FPD), plasma processing such as etching, sputtering, and 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 that functions as a lower electrode. The high-frequency electric field is applied between at least one of the electrodes while the chamber is kept in a vacuum state, and a high-frequency electric field is formed between the electrodes. On the other hand, what performs plasma processing is known.

  In such a plasma processing apparatus, a matching unit having a matching circuit for matching the impedance of a load (plasma) with the impedance of the transmission line on the high frequency power source side is provided between the electrode and the high frequency power source. High-frequency transmission is efficiently performed while suppressing reflected waves. However, immediately after the high frequency power is applied, impedance matching by the matching unit is not in time, and a reflected wave from the plasma side toward the high frequency power source is generated. Apart from this, after high frequency power is applied and sufficient alignment is achieved, voltage non-uniformity occurs in the in-plane pattern of the plasma due to in-plane non-uniformity of the plasma, etc. As a result, arc discharge (abnormal discharge) may occur in the chamber, particularly in the surface of the substrate to be processed.

  If such arc discharge continues, there is a possibility of damaging the substrate to be processed. Therefore, it is generally performed to detect the occurrence of such arc discharge or the probability thereof and to cut off the supply of high-frequency power. Yes.

  As a technique capable of accurately detecting the occurrence of such arc discharge, Patent Document 1 discloses a first time differentiating circuit that temporally differentiates a traveling wave voltage of high-frequency power toward the chamber, and returns from the chamber. A second time differentiating unit circuit for differentiating the reflected wave voltage of the high-frequency power with respect to time, a value corresponding to the difference between the time differentiated value of the reflected wave voltage and the time differentiated value of the traveling wave voltage, and the calculated difference A comparator that determines that arc discharge has occurred in the processing chamber when the value corresponding to the threshold value exceeds a predetermined threshold value, and the time differential value of the traveling wave voltage is negative, the value corresponding to the difference is less than the predetermined threshold value. A diode having a diode that changes 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 small is disclosed. Thereby, when the time differential value 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 differential value of the reflected wave voltage of the high frequency power and the time differential value of the traveling wave voltage becomes small. Since either the time differential value or the traveling wave voltage time differential value is changed, it is possible to accurately detect the occurrence of arc discharge.

  On the other hand, as a plasma processing apparatus as described above, a high frequency electricity for plasma generation is applied to the upper electrode or the lower electrode, and a bias power is applied to the lower electrode to attract ions in the plasma to the substrate to be processed. A technique for suppressing arc discharge in the surface of the substrate to be processed by pulse-modulating the power for use is also used (for example, Patent Document 2). In this technique, the bias power is lowered by pulse-modulating the bias power, and Vdc is lowered. That is, when Vdc is lowered, the Vdc in-plane uniformity margin is widened, and arc discharge in the substrate to be processed can be suppressed.

JP 2014-165437 A JP 2014-179598 A

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

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

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

  In order to solve the above problems, a first aspect of the present invention is a plasma processing apparatus for performing a predetermined plasma process on a substrate to be processed, the processing container containing the substrate to be processed, and the processing container 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 from the processing container toward the high-frequency power supply unit When the reflected wave power measured by the reflected wave power measuring unit meets a predetermined condition, an arc discharge occurs in the processing container. A determination unit that determines that there is a probability or that an arc discharge has actually occurred, and the pulse period of the pulse-modulated high-frequency power is different from the measurement period in the reflected wave power measurement unit To provide a plasma processing apparatus for.

  According to a second aspect of the present invention, there is provided a plasma processing apparatus for performing a predetermined plasma processing on a substrate to be processed, a processing container for storing 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 container, a substrate mounting table for mounting a substrate disposed in the processing container, and a pulse-modulated high-frequency power for bias applied to the substrate mounting table The reflected wave power measured by the reflected wave power measuring unit, the reflected wave power measuring unit that measures the reflected wave power returning from the processing container toward the high frequency power source unit at a predetermined cycle, A determination unit that determines that arc discharge is likely to occur in the processing container when the predetermined condition is satisfied, or that arc discharge has actually occurred, and the pulse-modulated high-frequency power And pulse period, the measurement period in the reflection wave power measuring unit to provide a plasma processing apparatus according to claim different.

  In the second aspect, the plasma generating means is configured to generate plasma on either the upper electrode provided facing the substrate mounting table and the substrate mounting table functioning as the upper electrode or the lower electrode. A high frequency power source for plasma generation for supplying high frequency power may be provided, and a capacitively coupled plasma may be generated by forming a high frequency electric field between the substrate mounting table functioning as the upper electrode and the lower electrode.

  In the first and second aspects, when the threshold value of reflected wave power is set and the value of the reflected wave power measured by the reflected wave power measurement unit exceeds the threshold value, the determination unit performs the processing. It can be determined that there is a probability that arc discharge will occur in the container, or that arc discharge has actually occurred. The threshold setting unit further sets a threshold of the determination unit, and the threshold setting unit sets the threshold to a relatively high value when starting the supply of high-frequency power or changing the output. The threshold value may be set to a relatively low value after the high-frequency power supply is stabilized.

  The determination unit includes a counter unit that counts the number of determinations that the reflected wave power exceeds the threshold, and when the count value of the counter unit exceeds a predetermined value, the determination unit It is possible to determine that there is a probability that arc discharge occurs in the processing container, or that arc discharge has actually occurred. The counter unit may return the count of the counter to 0 when the reflected wave power does not exceed a predetermined value.

  A stop control unit that outputs a signal to stop the high-frequency power or stop the apparatus when the determination unit determines that arc discharge is likely to occur in the processing container or 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 that accommodates a substrate to be processed, a gas supply unit that supplies 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, and measuring reflected wave power returning from the processing container toward the high frequency power supply unit at a predetermined period When the measured reflected wave power reaches a predetermined condition, it is determined that there is a probability that arc discharge will occur in the processing container, or that arc discharge has actually occurred, and the pulse modulation is performed. A plasma processing method is provided, wherein a pulse period of high-frequency power is different from a measurement period of the reflected wave power.

  According to a fourth aspect of the present invention, there is provided a processing container that accommodates a substrate to be processed, a gas supply unit that supplies a processing gas into the processing container, a plasma generation unit that generates plasma in the processing container, and the processing 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 that supplies pulse-modulated high-frequency power for bias to the substrate mounting table A method of measuring reflected wave power returning from the processing container toward the high-frequency power supply unit at a predetermined cycle, and when the measured reflected wave power reaches a predetermined condition, arc discharge is performed in the processing container. It is determined that an arc discharge has actually occurred, or the pulse period of the pulse-modulated high-frequency power is different from the measurement period of the reflected wave power. To provide a plasma processing method characterized.

  In the third and fourth aspects, there is a probability that arc discharge will occur in the processing container when the value of the measured reflected wave power exceeds a predetermined threshold value, or arc discharge actually occurs. It can be judged that it was done. The threshold value can be set to a relatively high value when the supply of high-frequency power is started or the output is changed, and the threshold value can be set to a relatively low value after the supply of high-frequency power has stabilized. .

  The number of times that the reflected wave power exceeds the threshold is counted, 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. It can be determined that occurrence has occurred. When 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 arc discharge has actually occurred, a signal for stopping the high-frequency power or stopping the apparatus can be output. The measurement period of the reflected wave power may be variable.

  According to the present invention, since the pulse period of the pulse-modulated high-frequency power is different from the measurement period in the reflected wave power measuring unit, the bias wave is measured when measuring the reflected wave power that is an index of occurrence of arc discharge. It is not affected by the reflected wave caused by the 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.

It is sectional drawing which shows the plasma etching apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the concept of the control part in the plasma etching apparatus which concerns on one Embodiment of this invention. It is a block diagram for demonstrating the structure of the control part in the plasma etching apparatus which concerns on one Embodiment of this invention. It is a block diagram which shows the main structures of the main control part of the control part in the plasma etching apparatus which concerns on one Embodiment of this invention. It is a figure which shows the state which actually detected the probability of arc discharge in the plasma etching apparatus which concerns on one Embodiment of this 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 an 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 plasma processing, for example, plasma etching processing, on an FPD glass substrate (hereinafter simply referred to as “substrate”) G. Has been. Examples of the FPD include a liquid crystal display (LCD), an electroluminescence (EL) display, a plasma display panel (PDP), and the like.

  The plasma etching apparatus 1 includes a chamber 2 as a processing container that accommodates 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 that functions 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 material 5 made of metal, for example, aluminum, an insulating shield ring 7 provided around the upper portion of the base material 5, and an insulating ring 8 provided around the side surface of the base material 5. And. Although not shown, an electrostatic chuck for electrostatically attracting the substrate G is provided on the surface of the substrate mounting table 3, and lifting pins used for transporting the substrate G are inserted into the substrate mounting table 3. Yes. Although not shown in the drawings, 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. In the shower head 20, a gas diffusion space 21 for diffusing the processing gas is formed therein, and a plurality of discharge holes 22 for discharging the processing gas are formed on the 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, and the processing gas supply pipe 25 is connected to a processing gas supply source 28. Yes. 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 according to the number of processing gases, and a processing gas supply pipe 25 extends from each processing gas supply source 28. A processing gas for plasma etching is supplied from the processing gas supply source 28. As the processing gas, a gas usually used in this field, such as a halogen-based gas, an O ₂ gas, or an Ar gas, can be used.

  A plurality of exhaust ports 29 (only two are shown) are formed at the edge or corner 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 degree of the exhaust pipe 31, and the interior of the chamber 2. And a vacuum pump 33 for exhausting through the exhaust pipe 31. Then, the inside of the chamber 2 is evacuated by the vacuum pump 33, and the inside of the chamber 2 is set and maintained in a predetermined vacuum atmosphere by adjusting the opening of the automatic pressure control valve (APC) 32 during the plasma etching process.

  On one side wall of the chamber 2, 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.

  A transmission line 41 for supplying high-frequency power is connected to the shower head 20 that functions 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. And the high frequency electric power for plasma generation of the frequency of the range of 4-100 MHz, for example, 13.56 MHz, is supplied to the shower head 20 from the 1st high frequency power supply part 43. FIG. Thereby, 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 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 platform 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 unit 52 and a second high frequency power supply unit 53 are connected to the transmission line 51. Then, from the second high-frequency power supply unit 53 to the substrate mounting table 3, a high-frequency power for bias (bias) for attracting ions to the substrate G with a frequency in the range of 0.4 to 6 MHz, for example, 3.2 MHz high-frequency power. Power). The second high-frequency power supply unit 53 has a built-in pulse modulation unit, and the output bias power is pulse-modulated 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,

  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 is connected to the shower head 20. The matching unit 52 is a matching circuit combining 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 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. A reflected wave power measuring unit 54 that measures the reflected wave power returning from the chamber 2 to the second high frequency power supply unit 53 is connected to the transmission line 51 between the second high frequency power supply unit 53 and the matching unit 52. The reflected wave power measuring unit 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 unit 53. At this time, the reflected wave power measurement unit 54 preferably makes the sampling period variable.

  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, such as 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, the open / close valve 26, the mass flow controller 27, the temperature control mechanism, and the like are connected via an I / O port or 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, and the like. Are connected to each other. The main control unit 101 includes a CPU 108, a RAM 109, and a ROM 110. The storage device 105 is for storing information, and reads information stored in a computer-readable storage medium 111. The storage medium 111 is not particularly limited, and 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 plasma etching apparatus 1 is controlled by the CPU 108 executing a program stored in the ROM 110 or the storage device 105. Further, by using the storage medium 111 that stores the processing recipe, the CPU 108 performs plasma on the substrate G in the plasma etching apparatus 1 that is the plasma processing apparatus of the present embodiment based on the processing recipe that is called from the storage medium. Processing is executed.

  FIG. 4 is a block diagram illustrating a main configuration of the main control unit 101 of the control unit 100 in 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 region for causing each component to execute predetermined control.

  The determination unit 121 compares the reflected wave power measured by the reflected wave power measuring units 44 and 54 with a predetermined threshold at the timing when each reflected wave power is measured, and the reflected wave power exceeds the predetermined threshold. For example, it is determined that an arc discharge is generated in the chamber 2. That is, since arc discharge in the chamber 2 occurs when the reflected wave power increases, a threshold is set in advance, and it is determined that there is a probability that arc discharge will occur, and high frequency power is stopped. Or stop the device. Note that the determination unit 121 may determine that 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) set. At this time, a determination signal determined to have exceeded the threshold value of the determination unit 121 is sent to the stop control unit 124. For example, when the setting value of the counter unit 123 is set to 1, the determination signal is sent to the stop control unit 124 when the determination that the reflected wave power of the determination unit 121 exceeds the threshold value is counted twice.

The reason why the counter unit 123 is used is as follows.
The reflected wave power measurement unit 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 unit 53 so that it does not overlap with the reflected wave caused by the pulse. If they overlap accidentally, there is a risk of accidentally shutting off the high-frequency power or the device. However, such a situation can be avoided by counting the number of times that the reflected wave power has been determined to exceed the threshold and issuing the determination signal after the number of times exceeds 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 continuously counts the determination that the threshold value has been exceeded twice or more.

  When the reflected wave power does not exceed the threshold value, the count number 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 problem does not occur in the reflected wave power measurement unit 44. Therefore, when arc discharge is detected based on the reflected wave power measuring unit 44, the setting value of the corresponding counter unit 123 is set to 0, and the determination signal is exceeded when the determination that the threshold value is exceeded is counted even once. May be sent to the stop control unit 124.

  The threshold setting unit 122 sets the threshold of the reflected wave power in the determination unit 121. As the threshold value, at least two kinds of threshold values, that is, a relatively high level threshold value and a relatively low level threshold value 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 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 threshold of a relatively high level is for preventing the determination unit 121 from determining that the condition for causing arc discharge in the chamber 2 has occurred due to a reflected wave inevitably generated when the plasma is started up. . The relatively low level threshold is preferably as low as possible (for example, 5% or less of the rated power value, preferably 2 to 5) in order to quickly cope with the reflected wave that may lead to arc discharge. % Is preferred).

  When the stop control unit 124 receives 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 a plasma etching apparatus. The etching process 1 is stopped.

  Note that the reflected wave power measurement unit 44 that measures the reflected wave power to the first high frequency power supply unit 43 is not provided, but only the reflected wave power measurement unit 54 is provided, and only the reflected wave power to the second high frequency power supply unit 53 is measured. You may make it do.

Next, the processing operation in the plasma etching apparatus 1 configured as described above will be described. The following processing operations are performed under the control of the control unit 100.
First, the inside of the chamber 2 is evacuated by the exhaust unit 30 to a predetermined pressure, the gate valve 36 is opened, the substrate G is loaded from the loading / unloading port 35 by a conveying means (not shown), and the lifter pin (not shown) is raised. The substrate G is received on the substrate, and the substrate G is placed on the substrate platform 3 by lowering the lifter pins. After the conveying means is retracted 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 in the chamber 2 is controlled by an automatic pressure control valve (APC) 32 while evacuating by the vacuum pump 33. Is adjusted to a predetermined degree of vacuum, and the flow rate is adjusted by the mass flow controller 27 from the processing gas supply source 28 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 process of the substrate G is advanced.

  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 the 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, the inside of the chamber 2 is evacuated and the inside of the chamber 2 is evacuated. Is purged with a purge gas. Then, the gate valve 36 is opened, and the substrate G is unloaded from the loading / unloading port 35 by a transfer means (not shown). Thereby, the plasma etching process for one substrate G is completed.

  In such plasma etching, impedance matching cannot be achieved by the matching device due to condition changes during processing, 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 cracked after processing. Therefore, it is necessary to detect the occurrence of 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. Thereby, since the effective bias power can be reduced and Vdc can be reduced, the Vdc in-plane uniformity margin is widened, and arc discharge such as ESD can be suppressed.

  However, in the technique of the above-mentioned Patent Document 1, in order to detect arc discharge that occurs steeply in a short time, the sampling period is usually about 2 μsec, and when the bias power is pulse-modulated, for each pulse of the bias power. The reflected wave generated in the error is misrecognized as arc discharge, and the arc discharge cannot be detected effectively.

  In the present embodiment, the arc discharge in the substrate surface is caused by the gradually increasing reflected wave power, and based on the fact that such reflected wave power continuously exceeds the threshold value, leading to cracking of the substrate, The focus is on detecting a predetermined value before the value of the reflected wave power reaches such a value that causes arc discharge in the substrate surface, or detection of 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 a high speed as assumed in Patent Document 1, and it is generated for each pulse of bias power. It is sufficient to detect the reflected wave power toward the high-frequency power source when no reflected wave is generated. Therefore, in the present embodiment, when determining the value of the reflected wave power, the pulse period of the pulse-modulated bias power of the second high-frequency power supply unit 53 and the reflected wave power sampling period in the reflected wave power measurement unit 54 (Measurement cycle) should be different.

  Thereby, when measuring the reflected wave power that is an index of occurrence of arc discharge, it is not affected by 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 pulse period of the bias power pulse is changed according to the measurement period of the reflected wave power measurement unit 54, or the reflected wave power measurement unit 54 having an appropriate sampling period is selected according to the pulse modulation period. Thus, it is possible to adjust the pulse period of the bias power and the sampling period of the reflected wave power, but by changing the sampling period of the reflected wave power measuring unit 54, it is not necessary to replace the reflected wave power measuring unit 54 In addition, the setting range of the bias power pulse can be expanded.

  In the present embodiment, the determination unit 121 determines whether or not the reflected wave power has exceeded the threshold value in a predetermined cycle, and the counter unit 123 includes the number of times the determination unit 121 determines that the reflected wave power has exceeded the threshold value. When the count value exceeds a predetermined value, a determination signal indicating that the reflected wave power exceeds the threshold is sent to the stop control unit 124, and the stop control unit 124 that has received the signal stops the high-frequency power or the device. Output a stop signal.

  The determination by the determining unit 121 is performed by comparing the reflected wave power measured by the reflected wave power measuring units 44 and 54 with a predetermined threshold value and determining whether the reflected wave power exceeds the 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 of starting the supply of high frequency, or the output It is possible to change the threshold level to a relatively low level when the reflected wave power is stabilized at a low value at a timing at which the threshold is changed. As a result, it is possible to prevent the erroneous determination that the arc discharge is caused by the reflected wave that is inevitably generated when the plasma is started up, and the threshold is set as much as possible after the reflected wave power is stabilized at a low value. It can be lowered to cope with an actual arc discharge before it occurs.

  In addition, 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 has exceeded the threshold, and when the count exceeds the set number of times, The 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 that receives the determination signal outputs the high frequency power or the stop signal for stopping the apparatus. When the sampling period of the wave power is accidentally overlapped, it is possible to prevent the high frequency power or the apparatus from being stopped by mistake. In this case, when the determination that the threshold value has been exceeded is continuously counted twice or more, by sending a signal to the stop control unit 124, it is possible to more reliably prevent the high frequency power or the device from being erroneously stopped. Can do.

  Further, when the determination unit 121 determines that the reflected wave power has exceeded the threshold value, the stop control unit 124 outputs a high-frequency power or a stop signal for stopping the apparatus, so that the substrate due to arc discharge in the substrate G plane. The high-frequency power or the apparatus itself can be surely stopped before the cracking occurs, and the cracking of the substrate can be prevented more reliably.

Next, a state in which the probability of arc discharge is actually detected in the plasma processing apparatus of this embodiment will be described with reference to FIG.
In FIG. 5, the first high frequency power supply unit for plasma generation has a continuous output, and the second high frequency power supply unit for bias is pulse-modulated, and has a cycle of 220 μsec and a duty ratio of 90%. The reflected wave power becomes high in the initial stage and stabilizes from the middle. Correspondingly, the threshold value is initially set to a high value, and is set to a low value after the reflected wave power is stabilized low. A large reflected wave is generated at the rising edge of the pulse of the second high frequency power supply unit, and in Patent Document 1, this is detected. In contrast, in this example, since the reflected wave power sampling period is 200 μsec, the bias power pulse period is different from the reflected wave power sampling period, and the influence of the reflected wave due to the bias power pulse is reduced. The reflected wave power can be measured without receiving. Also, in this example, the reflected wave power gradually increases and the reflected wave power exceeds the threshold value. If left as it is, arc discharge may occur in the substrate surface, and the arc discharge may lead to breakage of the substrate. There is. Therefore, in this example, the apparatus is stopped when it is detected twice that the reflected wave power exceeds the threshold value. Thereby, it was possible to prevent the substrate from cracking without causing arc discharge in the substrate surface.

<Other applications>
Note that the present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the idea of the present invention. For example, in the above-described embodiment, the case where the present invention is applied to a 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.

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 is shown. However, the high frequency power for bias that is pulse-modulated on the substrate mounting table is shown. The high frequency power of two frequencies for bias and plasma generation may be applied to the lower electrode. In addition, as long as it supplies a pulse-modulated high frequency power for bias to the substrate mounting table, the plasma generating means is not limited to the capacitively coupled plasma as shown in the above embodiment, but other plasma such as inductively coupled plasma. The present invention can also be applied to a plasma processing apparatus having a plasma generating means for generating the.
Absent.

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

  Furthermore, although the said embodiment demonstrated the example which applied this invention to the glass substrate for FPD, it cannot be overemphasized that it is applicable not only to the glass substrate for FPD but to other board | substrates, such as a semiconductor substrate. .

1: Plasma etching equipment (plasma processing equipment)
2; Chamber (processing container)
DESCRIPTION OF SYMBOLS 3; Substrate mounting base 5; Base material 20; Shower head 25: Processing gas supply pipe 28: Processing gas supply source 30; Exhaust part 42, 52; Matching unit 43; First high frequency power supply part 44, 54; 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; stop control unit G;

Claims (17)

A plasma processing apparatus for performing predetermined plasma processing on a 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 vessel;
A high-frequency power supply for supplying pulse-modulated high-frequency power to the electrodes;
A reflected wave power measuring unit that measures reflected wave power returning from the processing container toward the high frequency power source unit at a predetermined period;
A determination unit that determines that there is a probability that arc discharge will occur in the processing container or that arc discharge has actually occurred when the reflected wave power measured by the reflected wave power measurement unit reaches a predetermined condition. And
The plasma processing apparatus, wherein a pulse period of the pulse-modulated high-frequency power is different from a measurement period in the reflected wave power measurement unit. A plasma processing apparatus for performing predetermined plasma processing on a 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 generating means for generating plasma in the processing vessel;
A substrate mounting table for mounting a substrate disposed in the processing container;
A high-frequency power supply for supplying a pulse-modulated high-frequency power for bias to the substrate mounting table;
A reflected wave power measuring unit that measures reflected wave power returning from the processing container toward the high frequency power source unit at a predetermined period;
A determination unit that determines that there is a probability that arc discharge will occur in the processing container or that arc discharge has actually occurred when the reflected wave power measured by the reflected wave power measurement unit reaches a predetermined condition. And
The plasma processing apparatus, wherein a pulse period of the pulse-modulated high-frequency power is different from a measurement period in the reflected wave power measurement unit.   The plasma generating means generates plasma for supplying high-frequency power for generating plasma to either the upper electrode provided facing the substrate mounting table and the substrate mounting table functioning as the upper electrode or the lower electrode The plasma processing apparatus according to claim 2, further comprising: a high frequency power supply unit for generating a capacitively coupled plasma by forming a high frequency electric field between the substrate mounting table functioning as the upper electrode and the lower electrode. .   When the threshold value of the reflected wave power is set and the value of the reflected wave power measured by the reflected wave power measurement unit exceeds the threshold value, there is a probability that arc discharge occurs in the processing container. The plasma processing apparatus according to any one of claims 1 to 3, wherein it is determined that there is or that an arc discharge has actually occurred.   The threshold setting unit further includes a threshold setting unit configured to set a threshold of the determination unit, and the threshold setting unit sets the threshold to a relatively high value when starting to supply high-frequency power or changing an output. The plasma processing apparatus according to claim 4, wherein the threshold value is set to a relatively low value after power supply is stabilized.   The determination unit includes a counter unit that counts the number of determinations that the reflected wave power exceeds the threshold, and when the count value of the counter unit exceeds a predetermined value, the determination unit 6. The plasma processing apparatus according to claim 4, wherein it is determined that there is a probability that arc discharge occurs in the processing container, or that arc discharge has actually occurred.   The plasma processing apparatus according to claim 6, wherein the counter unit resets the count of the counter to 0 when the reflected wave power does not exceed a predetermined value.   A stop control unit that outputs a signal to stop the high-frequency power or stop the apparatus when the determination unit determines that arc discharge is likely to occur in the processing container or that arc discharge has actually occurred. The plasma processing apparatus according to claim 1, further comprising:   The plasma processing apparatus according to claim 1, 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 vessel;
A plasma processing method of performing plasma processing with a plasma processing apparatus having a high frequency power supply unit that supplies pulse-modulated high frequency power to the electrode,
The reflected wave power returning from the processing container toward the high frequency power supply unit is measured at a predetermined period, and when the measured reflected wave power reaches a predetermined condition, there is a probability that arc discharge occurs in the processing container. It is determined that there is an arc discharge actually or has occurred,
A plasma processing method, wherein a pulse period of the pulse-modulated high-frequency power is different from a measurement period of the reflected wave power. A processing container for storing a substrate to be processed;
A gas supply unit for supplying a processing gas into the processing container;
Plasma generating means for generating plasma in the processing vessel;
A substrate mounting table for mounting a substrate disposed in the processing container;
A plasma processing method for performing plasma processing with a plasma processing apparatus having a high-frequency power supply unit for supplying pulse-modulated high-frequency power for 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 period, and when the measured reflected wave power reaches a predetermined condition, there is a probability that arc discharge occurs in the processing container. It is determined that there is an actual or actual arc discharge,
A plasma processing method, wherein a pulse period of the pulse-modulated high-frequency power is different from a measurement period of the reflected wave power.   When the measured value of the reflected wave power exceeds a predetermined threshold value, it is determined that there is a probability that arc discharge occurs in the processing container, or that arc discharge has actually occurred. Item 12. The plasma processing method according to Item 10 or Item 11.   The threshold value is set to a relatively high value when the supply of high-frequency power is started or the output is changed, and the threshold value is set to a relatively low value after the supply of the high-frequency power is stabilized. The plasma processing method according to claim 12.   The number of times that the reflected wave power exceeds the threshold is counted, 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. 14. The plasma processing method according to claim 12 or 13, wherein it is determined that the occurrence of the gas has occurred.   The plasma processing method according to claim 14, wherein the count value is set to 0 when the reflected wave power does not exceed a predetermined value.   11. A signal for stopping high-frequency power or stopping the apparatus is output when it is determined that there is a probability that arc discharge will occur in the processing container or that arc discharge has actually occurred. The plasma processing method according to claim 1.   The plasma processing method according to claim 10, wherein a measurement period of the reflected wave power is variable.

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