Plasma processing equipment

Abstract

The state of plasma generated by high frequency power in the VHF or UHF band is monitored with high accuracy. [Solution] The plasma processing apparatus has a processing chamber, a mounting table, an upper electrode, a waveguide, a dielectric ring, and four or more electric field sensors. The processing chamber is disposed within a processing vessel. A substrate is placed on the mounting table within the processing chamber. The upper electrode faces the mounting table. The waveguide is positioned along the upper electrode and transmits high-frequency power in the VHF or UHF band. The dielectric ring separates the processing chamber from the waveguide. The four or more electric field sensors are disposed at positions such that, when a reference position is defined as 0, the angles formed by a line connecting the center of the dielectric ring to one of the four or more electric field sensors and a line connecting the center of the dielectric ring to each of the four or more electric field sensors are represented by 0, (t1·π / 2+π / 6), (t2·π / 2+2π / 6), and (t3·π / 2+3π / 6). t1, t2, and t3 are integers including 0.

Description

[Technical Field]

[0001] The present disclosure relates to a plasma processing apparatus. [Background technology]

[0002] For example, Patent Document 1 addresses the issue of measuring the state of a chamber that generates plasma, and discloses that "a traveling wave is applied from a high-frequency power source (having a frequency of, for example, 2.4 GHz) to an electrode in the plasma chamber via a matcher," and that "a signal measuring device receives the voltage applied to the electrode in the plasma chamber and the current flowing through the electrode from a VI probe positioned between the matcher and the plasma chamber." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-251071 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a plasma processing apparatus capable of accurately monitoring the state of plasma generated by high-frequency power in the VHF or UHF band. [Means for solving the problem]

[0005] One aspect of the present disclosure provides a plasma processing apparatus. The plasma processing apparatus includes a processing chamber, a mounting table, an upper electrode, a waveguide, a dielectric ring, and four or more electric field sensors. The processing chamber is disposed within a processing vessel. A substrate is mounted on the mounting table within the processing chamber. The upper electrode faces the mounting table. The waveguide is positioned along the upper electrode and transmits high-frequency power in the VHF or UHF band. The dielectric ring separates the processing chamber from the waveguide. The four or more electric field sensors are disposed at positions such that, when a reference position is defined as 0, the angles formed by a line connecting the center of the dielectric ring to one of the four or more electric field sensors and a line connecting the center of the dielectric ring to each of the four or more electric field sensors are expressed as 0, (t1·π / 2+π / 6), (t2·π / 2+2π / 6), and (t3·π / 2+3π / 6). t1, t2, and t3 are integers including 0. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to accurately monitor the state of plasma generated by high frequency power in the VHF band or UHF band. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of a plasma processing apparatus according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II in FIG. [Figure 3] FIG. 3 is a diagram showing an example of the monitored Vpp value of the voltage sensor placed at the output of the matching box and the sensor value of the electric field sensor installed at the high frequency power introduction part close to the plasma load. [Figure 4] FIG. 4 is a diagram showing an example of the Vpp value for each frequency and the sensor value of the electric field sensor when a variable frequency power supply is used as the VHF power supply. [Figure 5] FIG. 5 is a diagram showing an example of an electric field pattern for each TM mode directly below the upper electrode. [Figure 6] FIG. 6 is a diagram showing an example of the arrangement of electric field sensors in the circumferential direction. [Figure 7]FIG. 7 is a diagram showing an example of the sensor value of the electric field sensor in each TM mode. [Figure 8] FIG. 8 is a diagram showing an example of the sensor value of the electric field sensor in each TM mode. [Figure 9] FIG. 9 is a diagram showing an example of the sensor value of the electric field sensor in each TM mode. [Figure 10] FIG. 10 is a diagram showing an example of the sensor value of the electric field sensor in each TM mode. [Figure 11] FIG. 11 is a diagram showing an example of the sensor value of the electric field sensor in each TM mode. [Figure 12] FIG. 12 is a diagram for explaining an example of the arrangement of electric field sensors in the circumferential direction. [Figure 13] FIG. 13 is a schematic cross-sectional view showing an example of a plasma processing apparatus according to the second embodiment. [Figure 14] FIG. 14 is a cross-sectional view taken along the line II-II in FIG. [Figure 15] FIG. 15 is a schematic cross-sectional view showing an example of a plasma processing apparatus according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following describes in detail embodiments of the disclosed plasma processing apparatus with reference to the drawings. Note that the plasma processing apparatus according to the present disclosure is not limited to these embodiments, and the following embodiments can be appropriately combined within the scope of the present disclosure, so long as they do not cause any contradiction between the configurations and processing contents.

[0009] The drawings referred to below are schematic diagrams for the convenience of explanation, and therefore some details may be omitted and the dimensional proportions may not necessarily correspond to those of the actual objects.

[0010] [First embodiment] A plasma processing apparatus according to a first embodiment of the present disclosure will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic cross-sectional view showing an example of the plasma processing apparatus according to the first embodiment. Fig. 2 is a cross-sectional view taken along line II in Fig. 1.

[0011] Plasma processing apparatus 100 is an example of an apparatus that has a VHF (Very High Frequency) power supply 11, generates plasma using high frequency power in the VHF band of 30 MHz to 300 MHz output from VHF power supply 11, and performs plasma processing on a substrate. However, the present invention is not limited to this, and plasma processing apparatus 100 may also be an apparatus that has a UHF (Ultra High Frequency) source instead of VHF power supply 11, generates plasma using high frequency power in the UHF band of 300 MHz to 3 GHz, and performs plasma processing on a substrate.

[0012] The plasma processing apparatus 100 includes a processing vessel 1, a lid 2, and a mounting table 3. The processing vessel 1 is cylindrical and has a bottom, centered on an axis Ax, and is open at the top. The lid 2 is configured to seal the top opening of the processing vessel 1. A processing chamber U is disposed within the processing vessel 1. The mounting table 3 is located within the processing chamber U, and a substrate W is placed thereon. The substrate W is subjected to plasma processing within the processing chamber U. The substrate W is not particularly limited as long as it is subject to plasma processing, and examples thereof include semiconductor wafers, insulator substrates such as glass and alumina, and metal substrates. The mounting table 3 is disk-shaped, and its central axis coincides with the axis Ax.

[0013] The plasma processing apparatus 100 further includes an upper electrode 5 and a dielectric ring 7. The upper electrode 5 is located above the mounting table 3 and faces the mounting table 3. The upper electrode 5 is disk-shaped, and its central axis is aligned with the axis Ax. The upper electrode 5 has a metallic shower plate structure.

[0014] The space surrounded by the upper electrode 5, the lid 2, and the processing vessel 1 forms a waveguide 9. The waveguide 9 is located along the upper electrode 5. High frequency power in the VHF band (hereinafter referred to as "VHF") propagates through the waveguide 9. However, high frequency power in the UHF band may also propagate through the waveguide 9.

[0015] A diffusion chamber 5a and multiple gas holes 5b are formed in the upper electrode 5. The multiple gas holes 5b are through-holes that penetrate the lower surface of the upper electrode 5 to communicate the diffusion chamber 5a with the processing chamber U. The dielectric ring 7 is an annular member that has an inner diameter slightly larger than the diameter of the upper electrode 5 and an outer diameter slightly smaller than the diameter of the inner surface of the processing vessel 1, and separates the processing chamber U in the vacuum space from the waveguide 9 in the atmospheric space. The dielectric ring 7 is located between the upper electrode 5 and the processing vessel 1, at the end of the waveguide 9.

[0016] The lid 2 is disk-shaped and has an opening in the center. The central axis of the lid 2 is common with the axis Ax. The matching box 10 is located at the top of the plasma processing apparatus 100 so as to cover the central opening of the lid 2. The matching box 10 is electrically connected to the upper electrode via a transmission line 8. The transmission line 8 may be formed of a waveguide or a coaxial cable capable of transmitting high-frequency power in the VHF or UHF band.

[0017] The VHF power supply 11 is electrically connected to the upper electrode 5 via the matching box 10 and the transmission line 8. The VHF power supply 11 outputs a VHF wave and supplies the VHF power into the processing chamber 1. For example, the VHF power supply 11 outputs a VHF wave having a reference frequency F of 200 MHz and a wavelength λ of 1.5 m. The VHF power supply 11 may output a VHF wave having a frequency of 30 MHz to 300 MHz. The matching box 10 has a matching circuit for matching the impedance of the load side (upper electrode 5 side) of the VHF power supply 11 to the output impedance of the VHF power supply 11.

[0018] The VHF propagates through the waveguide 9 via the matching box 10 and the transmission line 8, passes through the dielectric ring 7, and is radiated into the processing chamber U. As a result, VHF power for generating plasma is supplied to the processing chamber U. The plasma processing apparatus 100 may supply high-frequency power in the UHF band to the processing chamber U instead of VHF band.

[0019] The plasma processing apparatus 100 further includes a gas supply source 16. The gas supply source 16 is connected to a gas supply pipe 17. The gas supply pipe 17 penetrates the lid 2, the waveguide 9, and a portion of the upper electrode 5, and communicates with the diffusion chamber 5a. The processing gas is supplied from the gas supply source 16, diffused in the diffusion chamber 5a via the gas supply pipe 17, and then supplied into the processing chamber U through the multiple gas holes 5b.

[0020] In the example shown in FIG. 1, the dielectric ring 7 has the same thickness as the upper electrode 5. However, the thickness of the dielectric ring 7 is not limited to this, and it may be thicker or thinner than the upper electrode 5. The dielectric ring 7 is formed from a dielectric material such as alumina ceramic. The dielectric ring 7 radiates VHF from the lower surface of the dielectric ring 7 all around. The dielectric ring 7 functions as a high-frequency introduction section that radiates VHF into the processing chamber U.

[0021] The mounting table 3 is electrically connected to a high frequency power supply 12. The high frequency power supply 12 applies a high frequency bias voltage in the RF (Radio Frequency) band to the mounting table 3 in order to attract mainly ions in the plasma.

[0022] A gas exhaust port 18 is formed at the bottom of the processing vessel 1. The gas exhaust port 18 is connected to an exhaust device 19. The exhaust device 19 exhausts gases inside the processing chamber U to the outside through the gas exhaust port 18.

[0023] A processing gas is introduced into the processing vessel 1, and the pressure inside the processing chamber U is reduced by the exhaust device 19 to a pressure at which plasma can be generated. When VHF power is introduced into the processing chamber U, plasma is generated from the processing gas in the processing chamber U by the VHF power. The substrate W is processed by the generated plasma.

[0024] The control device 20 processes computer-executable instructions to be executed by the plasma processing device 100. The control device 20 may be configured to control each element of the plasma processing device 100 to perform various processes. In one embodiment, part or all of the control device 20 may be included in the plasma processing device 100. The control device 20 may include a processing unit, a storage unit, and a communication interface. The control device 20 is implemented, for example, by a computer. The processing unit may be configured to read a program from the storage unit and execute the read program to perform various control operations. The program may be pre-stored in the storage unit or may be acquired via a medium when needed. The acquired program is stored in the storage unit and read from the storage unit by the processing unit for execution. The medium may be various computer-readable storage media or a communication line connected to the communication interface. The processing unit may be a central processing unit (CPU). The storage unit may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface communicates with the plasma processing apparatus 100 via a communication line such as a LAN (Local Area Network).

[0025] [Electric field sensor] The plasma processing apparatus 100 has an electric field sensor 14 that contacts the dielectric ring 7 that separates the processing chamber U and the waveguide 9. In the plasma processing apparatus 100, four or more electric field sensors 14 are arranged in the circumferential direction of the dielectric ring 7. The electric field sensor 14 is inserted from the outer surface of the processing vessel 1 into a through-hole that penetrates the sidewall of the processing vessel 1, and its tip is abutted against or pressed into the outer surface of the dielectric ring 7. In this way, the electric field sensor 14 is attached to the processing vessel 1 while contacting the dielectric ring 7. Since the electric field sensor 14 is provided in a position close to the plasma, it has heat resistance of 100°C or more.

[0026] The plasma processing apparatus 100 has four or more electric field sensors 14. In the example shown in FIG. 2, four electric field sensors 14a, 14b, 14c, and 14d are arranged at intervals of π / 6 around the circumferential direction of the dielectric ring 7. The tips of the four electric field sensors 14a, 14b, 14c, and 14d abut against the outer surface of the dielectric ring 7. By arranging four or more electric field sensors 14 at the dielectric ring 7 in this manner, the control device 20 monitors the electric field distribution of the standing wave near the plasma load based on the sensor values ​​detected by the four or more electric field sensors 14. This allows the control device 20 to accurately monitor the state of the plasma generated from the process gas using VHF. As a result, the plasma processing apparatus 100 can detect deviations of the center of the generated plasma from the axis Ax and shifts and losses in the effective VHF power output from the VHF power supply 11.

[0027] The electric field sensor 14 may be a coaxial probe pin. Alternatively, the electric field sensor 14 may be a spring-loaded probe pin. When the electric field sensor 14 is a spring-loaded probe pin, the elastic force of the spring can keep the pressing force of the electric field sensor 14 against the dielectric ring 7 constant. This allows the electric field sensor 14 to absorb thermal deformation of the dielectric ring 7 due to temperature changes and to sensitively monitor the electric field distribution of standing waves at locations close to the plasma load. Note that the four electric field sensors 14a, 14b, 14c, and 14d are one example of four or more electric field sensors 14, and the number and positions of the electric field sensors 14 are not limited to this.

[0028] In conventional plasma processing apparatuses, a voltage sensor is sometimes installed at the output of a matching box to monitor the state of plasma in the processing chamber. The voltage sensor monitors the Vpp value, which indicates the peak-to-peak voltage at the output of the matching box. The inventors installed a voltage sensor (not shown) at the output of the matching box 10 of a plasma processing apparatus 100 and monitored the state of plasma based on the Vpp value and the sensor value of the electric field sensor 14. Figure 3 shows an example of the monitored Vpp value of the voltage sensor installed at the output of the matching box and the sensor value of the electric field sensor 14 installed at the high-frequency power introduction section near the plasma load. V1 in Figure 3 is the Vpp value detected by the voltage sensor when plasma is generated from a processing gas using high-frequency power in the RF band of 13.56 MHz, and E1 is the sensor value detected by the electric field sensor 14 under the same conditions. V2 in Figure 3 is the Vpp value detected by the voltage sensor when plasma is generated from a processing gas using high-frequency power in the VHF band of 200 MHz, for example, and E2 is the sensor value detected by the electric field sensor 14 under the same conditions. The Vpp value and the sensor value are both voltage values.

[0029] The wavelength of a 13.56 MHz RF band radio frequency is 22 m, while the wavelength of a 200 MHz VHF band radio frequency is 1.5 m. Because the wavelength of the 13.56 MHz radio frequency is relatively long, the phase of the 13.56 MHz radio frequency hardly changes with the distance from the output of the matching box 10 to the dielectric ring 7, which is the introduction point for the radio frequency power into the processing chamber U. Therefore, there is almost no difference between the Vpp value V1 and the sensor value E1. As a result, when generating plasma from a processing gas using radio frequency power in the RF band, such as 13.56 MHz, by monitoring the Vpp value, it is possible to detect the level of voltage being supplied to the introduction point.

[0030] In contrast, because the wavelength of a 200 MHz VHF wave is relatively short, the phase of the 200 MHz VHF wave changes depending on the distance from the output of the matching box 10 to the dielectric ring 7. This causes a difference between the Vpp value V2 and the sensor value E2. As a result, when generating plasma from a process gas using high-frequency power in the VHF band, such as 200 MHz, there is no correlation between the Vpp value and the voltage supplied to the introduction part, and the plasma state cannot be accurately determined from the Vpp value.

[0031] FIG. 4 shows an example of the Vpp value for each frequency and the sensor value of the electric field sensor 14 when a variable frequency power supply is used as the VHF power supply 11. The horizontal axis of FIG. 4 indicates the frequency of the high frequency power used to generate plasma. Here, the reference frequency of the high frequency power is F, and each frequency is indicated by the difference from the reference frequency. The left vertical axis of FIG. 4 indicates the sensor value detected by the electric field sensor 14. The right vertical axis indicates the Vpp value detected by the voltage sensor in the matching box 10. Region S indicates the frequency range of high frequency power where plasma does not ignite, and region T indicates the frequency range of high frequency power where plasma ignites. As shown in FIG. 4, in the plasma processing apparatus 100, plasma does not ignite and is not generated when high frequency power has a frequency that is +10 MHz or less different from the reference frequency F. When high frequency power has a frequency that is more than +10 MHz different from the reference frequency F, plasma ignites and is generated.

[0032] The larger the Vpp value and the sensor value of the electric field sensor 14, the easier it is for plasma to ignite. In Figure 4, line P shows the sensor value of the electric field sensor 14 at each frequency, and line Q shows the Vpp value at each frequency. Note that both the Vpp value and the sensor value are voltage values. As line P and line Q show, the Vpp value and the sensor value of the electric field sensor 14 at each frequency of high-frequency power are roughly the same, but there is a difference in the values ​​on the high-frequency side, indicating that the difference in the measurement positions has an effect.

[0033] Specifically, the sensor value of the electric field sensor 14 indicated by line P has a peak value within region T where plasma ignites. In other words, there is a correlation between the sensor value of the electric field sensor 14 and the frequency band where plasma ignites. In contrast, the Vpp value indicated by line Q has a peak value within region S where plasma does not ignite. In other words, there is no correlation between the Vpp value and the frequency band where plasma ignites.

[0034] From the above, when high-frequency power in the VHF band or higher is supplied, it is difficult to accurately grasp the plasma state, including the ease of plasma ignition, from the Vpp value, and it is expected that a discrepancy will occur between the Vpp value and the process result. Therefore, the plasma processing apparatus 100 uses the sensor values ​​of four or more electric field sensors 14 positioned circumferentially around the dielectric ring 7 to monitor the electric field (voltage) distribution of the standing wave at a location close to the plasma load. This allows the plasma processing apparatus 100 to accurately monitor the plasma state. As a result, the plasma processing apparatus 100 can obtain accurate process results and detect abnormalities in the apparatus, such as broken parts.

[0035] For example, if 500 W of VHF power is input from VHF power supply 11 into processing chamber U, plasma corresponding to the 500 W of power is generated. However, if a part of plasma processing apparatus 100 is damaged or an abnormal discharge occurs in waveguide 9, the VHF power will be lost before it is input into processing chamber U. For example, if the VHF power loss is 200 W, plasma corresponding to 300 W of power will be generated, which is the input 500 W minus the 200 W loss. In this case, plasma processing apparatus 100 can determine the shift in the effective power of the VHF power from the change in the electric field distribution of the standing wave detected by electric field sensor 14 near the plasma load. This allows plasma processing apparatus 100 to detect abnormalities in the apparatus, such as loss of VHF power.

[0036] [VHF electric field distribution] The electric field patterns of standing waves detected by the electric field sensor 14 will be described with reference to Figs. 5 to 12. Fig. 5 is a diagram showing an example of the electric field pattern for each TM mode directly below the upper electrode 5. Fig. 6 is a diagram showing an example of the circumferential arrangement of the electric field sensor 14. Figs. 7 to 11 are diagrams showing examples of the sensor values ​​of the electric field sensor in each TM mode. Fig. 12 is a diagram for explaining an example of the circumferential arrangement of the electric field sensor 14.

[0037] As described above, in the plasma processing apparatus 100, four or more electric field sensors 14 are arranged around the circumferential direction of the dielectric ring 7 near the plasma load so that monitoring accuracy does not decrease depending on the distance from the output of the matching box 10 to the dielectric ring 7, which is the introduction part of the VHF power. The tip of each electric field sensor 14 contacts the dielectric ring 7.

[0038] The plasma processing apparatus 100 searches for a plasma ignition area and accurately grasps the plasma state based on the sensor values ​​of the four or more electric field sensors 14 using the control device 20. The four or more electric field sensors 14 detect the electric field of a standing wave propagating through the dielectric ring 7. The control device 20 receives the sensor values ​​detected by the four or more electric field sensors 14 at the dielectric ring 7 via a communication interface.

[0039] The control device 20 then monitors the plasma state, such as the plasma electric field distribution and plasma intensity, based on the differences between the sensor values ​​of the four or more electric field sensors 14. This allows the control device 20 to detect shifts in the effective power input to the plasma, damage to equipment parts, abnormal discharge within the equipment, deviations in the center position of the plasma, and the in-plane distribution of the plasma.

[0040] The electric field patterns for each TM mode shown in Figure 5 are the electric field distribution of the standing wave directly below the upper electrode 5 for each TM mode. The standing wave has an electric field pattern that occurs for each TM mode, represented by TM (m, n: m = 0 to 2, n = 1 to 3). TM (0, 1) is also called TM mode 0, TM (1, 1) is called TM mode 1, and TM (2, 1) is called TM mode 2. Note that Figure 5 shows that when m = 1 and two columns, the electric field pattern occurs symmetrically with respect to the horizontal or vertical axis, but even with the same TM mode, the electric field pattern may occur at a position rotated in the circumferential direction.

[0041] At VHF, the electric field distribution changes significantly when the TM mode changes. In the TM modes in rows where m is 1 and 2, the electric field distribution is non-uniform in the circumferential direction. Therefore, in the TM modes in rows where m is 1 and 2, except for TM (2, 3), the circumferential electric field distribution of the plasma in each TM mode can be determined from the difference between the sensor values ​​of four or more electric field sensors 14 arranged in the circumferential direction on the outer surface of the dielectric ring 7.

[0042] The TM mode in the column where m is 0 has a uniform electric field distribution in the circumferential direction (hereinafter also referred to as the circumferential direction). In other words, the TM mode in the column where m is 0 has the same electric field in the circumferential direction but different electric fields in the radial direction. Therefore, for the TM mode in the column where m is 0, the radial electric field distribution of the plasma generated in each TM mode cannot be grasped using four or more electric field sensors 14 arranged in the circumferential direction. In this case, as will be described later, the concentric electric field distribution of the standing wave in each TM mode can be detected by the difference between the sensor values ​​of three or more electric field sensors 14 arranged in the vertical direction on the outer surface of the dielectric ring 7. Similarly, since the electric fields in the circumferential direction are almost the same for TM (2, 3), the concentric electric field distribution of the standing wave can be detected by the difference between the sensor values ​​of three or more electric field sensors 14 arranged in the vertical direction.

[0043] The inventors confirmed that when a process gas is supplied to the plasma processing apparatus 100 to generate plasma and form a film, there is a correlation between the electric field distribution detected from the sensor value of the electric field sensor 14 and the thickness of the formed film. From the above, it is believed that there is a correlation between the electric field distribution detected from the sensor value of the electric field sensor 14 and the process results. Therefore, if the difference between the sensor values ​​of the electric field sensor 14 indicates a TM mode 0 electric field distribution with almost no bias in the circumferential and radial electric field distributions, the plasma processing apparatus 100 can determine, via the control device 20, that the plasma state is normal. On the other hand, if the difference between the sensor values ​​of the electric field sensor 14 indicates an electric field distribution other than TM mode 0, the plasma processing apparatus 100 can determine, via the control device 20, that the plasma state is abnormal. If the plasma state is determined to be abnormal, the mode cannot be used as a process condition, so the plasma processing apparatus 100 can control the control device 20 to stop the VHF output.

[0044] FIG. 6 shows the electric field distribution in TM mode 1. In FIGS. 6 to 12, the electric field sensors 14 are schematically represented by triangles (△). FIG. 6(a) shows the electric field sensors 14 arranged in the circumferential direction at equal intervals of π / 4. The electric field (voltage) indicated by the sensor value detected by the reference electric field sensor 14 arranged at the boundary between the first and second quadrants is normalized to 1. In this case, the electric fields detected by the five electric field sensors 14 arranged in the first and second quadrants are expressed as 0.2, 0.7, 1, 0.7, and 0.2, centered around the reference electric field sensor 14.

[0045] FIG. 6(b) shows electric field sensors 14 arranged in the circumferential direction at equal intervals of π / 6. The electric field indicated by the sensor value detected by the reference electric field sensor 14 arranged at the boundary between the first and second quadrants is normalized to 1. In this case, the electric fields detected by the seven electric field sensors 14 arranged in the first and second quadrants are expressed as 0.2, 0.3, 0.7, 1, 0.7, 0.3, and 0.2, centered on the reference electric field sensor 14. Although not shown in FIGS. 6(a) and 6(b), the electric field sensors 14 in the third and fourth quadrants indicate approximately the same electric field as the opposing electric field sensors 14 in the first and second quadrants.

[0046] FIG. 7 shows the electric field distribution in TM mode 0. FIG. 7(a) shows electric field sensors 14 arranged in the circumferential direction at equal intervals of π / 4. When the electric field indicated by the sensor value detected by the reference electric field sensor 14 is normalized to 1, the electric fields detected by the three electric field sensors 14 arranged in the first and second quadrants are expressed as 1, 1, 1. In this case, the control device 20 may predict that the plasma state is in TM mode 0 and determine that the plasma state is normal.

[0047] 7(b) shows electric field sensors 14 arranged in the circumferential direction at equal intervals of π / 6. When the electric field detected by the reference electric field sensor 14 is normalized to 1, the electric fields indicated by the sensor values ​​detected by the four electric field sensors 14 arranged in the first and second quadrants are expressed as 1, 1, 1, 1. In this case, the control device 20 may predict that the plasma state is TM mode 0 and determine that the plasma state is normal.

[0048] FIG. 8 shows the electric field distribution in TM mode 1. In TM mode 1, plasma distribution occurs every π. FIGS. 8(a) to 8(d) show three electric field sensors 14 arranged in the circumferential direction at equal intervals of π / 4. The electric field distributions in FIGS. 8(b) to 8(d) show the electric field distributions rotated approximately 45°, 90°, and 30° clockwise from the electric field distribution in FIG. 8(a). FIGS. 8(a) to 8(d) show the electric fields indicated by the sensor values ​​detected by the three electric field sensors 14 as numerical values, where the electric field detected by the reference electric field sensor 14 is set to 1. The numerical values ​​are 0.7, 1, and 0.7 in FIG. 8(a), 1, 0.5, and 0.2 in FIG. 8(b), 0.5, 0.2, and 0.5 in FIG. 8(c), and 0.8, 0.7, and 0.3 in FIG. 8(d). According to this, when three electric field sensors 14 are arranged in the circumferential direction at equal intervals of π / 4, the difference between the three sensor values ​​is large, and the electric field distribution in the circumferential direction can be detected. This allows the control device 20 to grasp abnormalities in the plasma state.

[0049] However, as shown in FIG. 9, the spacing between the electric field sensors 14 is changed, and three electric field sensors 14 are arranged in the circumferential direction at equal intervals of π / 6. In this case, the electric field values ​​indicated by the sensor values ​​are 0.8, 1, and 0.8 in the counterclockwise direction in FIG. 9(a), 0.8, 0.7, and 0.3 in FIG. 9(b), 0.3, 0.2, and 0.3 in FIG. 9(c), and 1, 0.8, and 0.3 in FIG. 9(d). Therefore, when the three electric field sensors 14 are arranged in the circumferential direction at equal intervals of π / 6, the difference between the three sensor values ​​may be small, making it difficult for the control device 20 to detect the difference in the electric field distribution in the circumferential direction. This may prevent the control device 20 from detecting an abnormality in the plasma state.

[0050] Therefore, as shown in FIG. 10, the number of electric field sensors 14 is varied, and four electric field sensors 14 are arranged circumferentially at equal intervals of π / 6. In this case, the electric field values ​​in the counterclockwise direction are 0.8, 1, 0.8, and 0.3 in FIG. 10(a); 0.8, 0.7, 0.3, and 0.3 in FIG. 10(b); 0.3, 0.2, 0.3, and 0.8 in FIG. 10(c); and 1, 0.8, 0.3, and 0.2 in FIG. 10(d). According to this, when four electric field sensors 14 are arranged circumferentially at equal intervals of π / 6, the control device 20 can detect the circumferential electric field distribution from the large difference between the four sensor values. This allows the control device 20 to identify abnormalities in the plasma state.

[0051] Figure 11 shows the electric field distribution in TM mode 2. In TM mode 2, plasma modes occur every π / 2. Figures 11(a) and (b) show three electric field sensors 14 arranged circumferentially at equal intervals of π / 4. Figures 11(c) and (d) show four electric field sensors 14 arranged circumferentially at equal intervals of π / 6. The electric field distributions in Figures 11(b) and (d) show the electric field distributions rotated several tens of degrees clockwise from the electric field distributions in Figures 11(a) and (c), respectively. In this case, the electric field values ​​indicated by the sensor values ​​are 1, 0.2, and 1 in the counterclockwise direction in Figure 11(a), 0.6, 0.5, and 0.5 in Figure 11(b), 0.7, 0.3, 0.3, and 0.7 in Figure 11(c), and 0.7, 0.2, 0.7, and 0.5 in Figure 11(d).

[0052] According to this, when three electric field sensors 14 are arranged in the circumferential direction at equal intervals of π / 4, there may be no difference between the three sensor values, making it difficult for the control device 20 to detect the circumferential electric field distribution. As a result, the control device 20 may not be able to detect an abnormality in the plasma state. On the other hand, when four electric field sensors 14 are arranged in the circumferential direction at equal intervals of π / 6, there is a large difference between the four sensor values, and the control device 20 can detect the circumferential electric field distribution from the difference. This allows the control device 20 to detect an abnormality in the plasma state.

[0053] There may be four or more electric field sensors 14 positioned in the circumferential direction of the dielectric ring 7. The four or more electric field sensors are positioned such that, when the reference position is 0, the angles formed by a line connecting the center of the dielectric ring 7 to one of the four or more electric field sensors 14 and a line connecting the center of the dielectric ring 7 to each of the four or more electric field sensors are represented by 0, (t1·π / 2+π / 6), (t2·π / 2+2π / 6), and (t3·π / 2+3π / 6).

[0054] The circumferential arrangement of the four electric field sensors 14 will be further described with reference to FIG. 12. FIG. 12 is a diagram illustrating an example of the circumferential arrangement of the four electric field sensors 14. As shown in FIG. 5, TM mode 0 has a uniform concentric electric field pattern in the circumferential direction, TM mode 1 has the same electric field pattern every π in the circumferential direction, and TM mode 2 has the same electric field pattern every π / 2 in the circumferential direction. Therefore, in TM modes 0 to 2, the smallest unit at which an electric field pattern appears in the circumferential direction is π / 2. Therefore, as shown in FIG. 12, the circumferential direction of the dielectric ring 7 is divided into areas 0, 1, 2, and 3, each divided by π / 2. The electric field sensors 14a to 14l can be arranged at intervals of π / 6 in the circumferential direction. A method for determining the positions of the four electric field sensors 14, which monitor the electric field of a standing wave propagating through the dielectric ring 7, from among the electric field sensors 14a to 14l will be described.

[0055] For ease of explanation, one of the four electric field sensors 14 will be referred to as electric field sensor 14a. The line connecting the center of the dielectric ring 7 (hereinafter referred to as "axis Ax") and electric field sensor 14a will be indicated as line L1. The four electric field sensors 14 are placed at positions where the angles formed by line L1 shown in Fig. 12 and lines L1, L2, L3, and L4 connecting the axis Ax and each of the four electric field sensors 14 are 0, (t1·π / 2+π / 6), (t2·π / 2+2π / 6), and (t3·π / 2+3π / 6).

[0056] t1, t2, and t3 are integers including 0. t1, t2, and t3 indicate areas where four or more electric field sensors 14 are arranged among the areas every π / 2. π / 6, 2π / 6, and 3π / 6 indicate positions obtained by dividing the area defined by t1, t2, and t3 into π / 6 intervals. When t1, t2, and t3 are 0, the four electric field sensors 14 are positioned circumferentially at intervals of π / 6 within area 0, where the angles formed by line L1 and each of lines L1, L2, L3, and L4 are between 0 and π / 2. In the example of FIG. 12, four electric field sensors 14a to 14d are positioned within area 0. In this way, four or more electric field sensors 14 may be positioned circumferentially in any of four areas 0 to 3, which are between 0 and π / 2, between π / 2 and π, between π and 3π / 2, and between 3π / 2 and 2π.

[0057] When at least one of t1, t2, and t3 is 1 or greater, the four electric field sensors 14 are positioned in the circumferential direction so that the angles formed between the line L1 and each of the lines L1, L2, L3, and L4 are distributed across two or more of the four areas 0 to 3. For example, when t1 is 1 and t2 and t3 are 2, the four electric field sensors 14 are positioned at positions where the angles formed between the line L1 and each of the lines L1, L2, L3, and L4 shown in FIG. 12 are 0, (π / 2+π / 6), (π+2π / 6), and (π+3π / 6). In the example of FIG. 12, four electric field sensors 14a, 14e, 14i, and 14j are positioned. In this manner, four or more electric field sensors 14 may be positioned in the circumferential direction so that the angles formed between the line L1 and each of the lines L1, L2, L3, and L4 are 0, (π / 2+π / 6), (π+2π / 6), and (π+3π / 6).

[0058] [Effects of the first embodiment] Similarly, four or more electric field sensors 14 are arranged at the positions described above in the circumferential direction of dielectric ring 7. This allows control device 20 to detect bias in the circumferential electric field distribution of the standing wave close to the plasma load from the difference between the sensor values ​​monitored by four or more electric field sensors 14. This makes it possible to detect circumferential deviations in the plasma distribution, circumferential deviations in the plasma input power, etc.

[0059] For example, if the difference between the sensor values ​​of four or more electric field sensors 14 indicates a TM mode 0 electric field distribution with almost no bias in the circumferential electric field distribution, the control device 20 can determine that the plasma distribution is approximately uniform and that the plasma state is normal. On the other hand, if the difference between the sensor values ​​of four or more electric field sensors 14 indicates an electric field distribution other than TM mode 0, the control device 20 can determine that the plasma distribution is non-uniform and that the plasma state is abnormal. In this way, the control device 20 can determine whether the plasma state is normal or abnormal based on the difference between the sensor values ​​of four or more electric field sensors 14. If the plasma state is determined to be abnormal, the control device 20 may, for example, stop the VHF output and stop the process.

[0060] Furthermore, the control device 20 can detect bias in the electric field distribution in the circumferential direction of the substrate W facing the upper electrode 5 based on sensor values ​​detected by four or more electric field sensors 14 in the circumferential direction of the dielectric ring 7.

[0061] Furthermore, the control device 20 can detect bias in the bias voltage applied to the disk-shaped mounting table 3 that shares the axis Ax with the dielectric ring 7, based on sensor values ​​detected by four or more electric field sensors 14 in the circumferential direction of the dielectric ring 7. This makes it possible to determine whether or not plasma instability is occurring due to excessive application of the bias voltage.

[0062] [Second embodiment] Next, a plasma processing apparatus according to a second embodiment of the present disclosure will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a schematic cross-sectional view showing an example of the plasma processing apparatus according to the second embodiment. Fig. 14 is a cross-sectional view taken along the line II-II in Fig. 13.

[0063] In the plasma processing apparatus 100A according to the second embodiment, three or more electric field sensors 14 are positioned along the propagation direction of the VHF wave propagating through the dielectric ring 7, and the effective wavelength λ of the VHF wave is eff The electric field sensors 14 are arranged within an area that is ¼ of the area of ​​the plasma processing apparatus 100A. Other configurations of the plasma processing apparatus 100A are the same as those of the plasma processing apparatus 100 according to the first embodiment. Therefore, in the plasma processing apparatus 100A, only the arrangement of the electric field sensors 14 will be described, and a description of the other configurations will be omitted.

[0064] The plasma processing apparatus 100A has three or more electric field sensors 14 arranged along the propagation direction of the VHF wave propagating through the dielectric ring 7. In the example of Fig. 13, the propagation direction of the VHF wave propagating through the dielectric ring 7 is the vertical direction (thickness direction) of the dielectric ring 7, and the three or more electric field sensors 14 detect the effective wavelength λ of the VHF wave in the vertical direction of the dielectric ring 7. eff The dielectric constant of the dielectric ring 7 is ε r , where λ is the free space wavelength, the effective wavelength of VHF is λ eff is expressed by the following formula: λ eff =λ / √ε r

[0065] In the examples of Figures 13 and 14, the three electric field sensors 14a, 14b, and 14c are arranged at the same position in the circumferential direction of the dielectric ring 7, in order from top to bottom in the vertical direction of the dielectric ring 7. Furthermore, the three electric field sensors 14d, 14e, and 14f are arranged at the same position in the circumferential direction of the dielectric ring 7, in order from top to bottom in the vertical direction of the dielectric ring 7. The electric field sensors 14a and 14d are positioned opposite each other in the circumferential direction. The electric field sensors 14b and 14e are positioned opposite each other in the circumferential direction. The electric field sensors 14c and 14f are positioned opposite each other in the circumferential direction.

[0066] Electric field sensors 14a to 14f are inserted from the outer surface of processing vessel 1 into through-holes penetrating the sidewall of processing vessel 1, and are attached to dielectric ring 7 so that their tips abut or are pressed into the outer surface of dielectric ring 7. Electric field sensors 14a to 14c contact dielectric ring 7 from the same direction. Similarly, electric field sensors 14d to 14f contact dielectric ring 7 from the same direction. Since electric field sensor 14 is provided in a position close to plasma, it has heat resistance of 100°C or higher.

[0067] 5, the TM mode in the column where m is 0 has a uniform concentric electric field distribution. Therefore, the concentric electric field distribution of the standing wave cannot be detected by the difference between the sensor values ​​of four or more electric field sensors 14 arranged circumferentially around the outer surface of the dielectric ring 7. Therefore, the plasma processing apparatus 100A detects the concentric electric field distribution of the standing wave by measuring the difference between the sensor values ​​of four or more electric field sensors 14 arranged circumferentially around the outer surface of the dielectric ring 7. eff Three or more electric field sensors 14 are arranged vertically within an area of ​​1 / 4 of the area.

[0068] Three or more electric field sensors 14 arranged vertically detect the effective wavelength λ of VHF. eff By detecting the electric field (voltage) at positions arranged within an area 1 / 4 of the area, the control device 20 can estimate the electric field distribution of one VHF wavelength. This allows the control device 20 to detect the concentric electric field distribution of the standing wave by calculating the difference between the sensor values ​​of three or more electric field sensors 14 arranged vertically. This allows the control device 20 to determine which of the concentric distribution modes, TM mode 0 (TM(0,1)), TM(0,2), or TM(0,3), is present.

[0069] For example, the determination of the TM mode will be described below assuming that three electric field sensors 14a, 14b, and 14c output sensor values ​​projecting the electric field at the center, the middle point between the center and the periphery, and the periphery of a TM mode concentric distribution. If the sensor values ​​detected by electric field sensors 14a, 14b, and 14c are 0.7, 1, and 1, respectively, the control device 20 can detect that the electric field distribution is TM mode 0 based on the differences between the sensor values. If the sensor values ​​detected by electric field sensors 14a, 14b, and 14c are 0.8, 0.3, and 0.5, respectively, the control device 20 can detect that the electric field distribution is TM(0,2) based on the differences between the sensor values. If the sensor values ​​detected by electric field sensors 14a, 14b, and 14c are 0.8, 0.4, and 0.2, respectively, the control device 20 can detect that the electric field distribution is TM(0,3) based on the differences between the sensor values. Note that the sensor values ​​described here are merely examples and are not limiting.

[0070] If the difference between the sensor values ​​of the electric field sensors 14 indicates an electric field distribution of TM mode 0, the control device 20 can determine that the plasma state is normal. On the other hand, if the difference between the sensor values ​​of the electric field sensors 14 indicates an electric field distribution other than TM mode 0, the control device 20 can determine that the plasma state is abnormal. If the plasma state is determined to be abnormal, the control device 20 may perform control to stop the VHF output and abort the process.

[0071] However, it is sufficient to arrange three or more electric field sensors 14 in the vertical direction. When three electric field sensors 14a, 14b, and 14c are arranged in the vertical direction, electric field sensors 14d, 14e, and 14f do not need to be arranged.

[0072] As shown in Figure 13, when electric field sensors 14a-14c and electric field sensors 14d-14f are arranged in a 3:3 configuration, control device 20 detects the concentric electric field distribution of the standing wave from the difference between the sensor values ​​of vertically arranged electric field sensors 14a-14c. Control device 20 also detects the concentric electric field distribution of the standing wave from the difference between the sensor values ​​of vertically arranged electric field sensors 14d-14f. This allows control device 20 to detect bias in the electric field distribution in the radial direction of substrate W from the sensor values ​​output from three or more electric field sensors 14. Furthermore, the circumferential electric field distribution can be detected by at least one combination of electric field sensors 14a and 14d, electric field sensors 14b and 14e, or electric field sensors 14c and 14f.

[0073] The electric field sensors 14a to 14c may be arranged in a 3:1 ratio to any of the electric field sensors 14d to 14f. In this case, the control device 20 detects the concentric electric field distribution of the standing wave from the difference between the sensor values ​​of the electric field sensors 14a to 14c. In addition, the control device 20 detects the circumferential electric field distribution of the standing wave using the electric field sensors 14c and 14f.

[0074] For example, suppose that the sensor values ​​detected by the electric field sensors 14c and 14f are 0.5 and 0.9, respectively. If a preset threshold indicating bias in the electric field distribution is 0.2, the control device 20 may determine that the difference between these sensor values ​​is equal to or greater than the threshold, and therefore that the tilt of the mounting table 3 has caused bias in the plasma.

[0075] In this way, the plasma processing apparatus 100A may further include electric field sensors 14 arranged in the circumferential direction corresponding to at least one of the three or more electric field sensors 14 arranged in the vertical direction. The control device 20 can detect, for example, the tilt of the mounting table 3 based on the sensor values ​​output from the electric field sensors 14 arranged in the circumferential direction. If the mounting table 3 is tilted, the spread of the plasma changes depending on the bias voltage applied to the mounting table 3. If the sensor value detected by electric field sensor 14f is greater than that of electric field sensor 14c, the plasma intensity is stronger on the electric field sensor 14f side than on the electric field sensor 14c side. Therefore, the control device 20 may determine that the tilt of the mounting table 3 causes the plasma intensity to fluctuate, resulting in a bias in the plasma.

[0076] [Effects of the second embodiment] In this way, the plasma processing apparatus 100A can detect the concentric electric field distribution of the standing wave using three or more vertical electric field sensors 14. Furthermore, the plasma processing apparatus 100A can detect the tilt of the mounting table 3 and the bias of the plasma by arranging electric field sensors 14 in the circumferential direction corresponding to at least one of the three or more vertical electric field sensors 14.

[0077] Furthermore, the plasma processing apparatus 100A may have three or more electric field sensors 14 arranged in the circumferential direction corresponding to at least one of the three or more vertical electric field sensors 14. In this way, the plasma processing apparatus 100A has three or more electric field sensors 14 in the vertical direction and four or more electric field sensors 14 in the circumferential direction, thereby achieving the effects of the first embodiment and the second embodiment.

[0078] [Third embodiment] Next, a plasma processing apparatus according to a third embodiment of the present disclosure will be described with reference to Fig. 15. Fig. 15 is a schematic cross-sectional view showing an example of the plasma processing apparatus according to the third embodiment.

[0079] In the plasma processing apparatus 100B according to the third embodiment, three or more electric field sensors 14 are positioned along the propagation direction of the VHF wave propagating through the waveguide 9, and the effective wavelength λ of the VHF wave is eff The electric field sensors 14 are arranged within an area that is ¼ of the area of ​​the plasma processing apparatus 100B. Other configurations of the plasma processing apparatus 100B are the same as those of the plasma processing apparatus 100A according to the second embodiment. Therefore, in the plasma processing apparatus 100B, only the arrangement of the electric field sensors 14 will be described, and a description of the other configurations will be omitted.

[0080] The plasma processing apparatus 100B has three or more electric field sensors 14 arranged in the propagation direction of the VHF wave propagating through the waveguide 9. In the example of Fig. 15, the propagation direction of the VHF wave propagating through the waveguide 9 is along the sidewall of the processing chamber 1, and the three electric field sensors 14a to 14c are arranged along the sidewall of the processing chamber 1 in a direction corresponding to the effective wavelength λ eff Each will be placed within an area of ​​1 / 4 of the original.

[0081] The three electric field sensors 14a, 14b, and 14c are arranged in the same circumferential position on the inner surface of the processing vessel 1 and in the vertical direction from top to bottom on the side wall of the processing vessel 1. The three electric field sensors 14d, 14e, and 14f are arranged in the same circumferential position on the inner surface of the processing vessel 1 and in the vertical direction from top to bottom on the side wall of the processing vessel 1. The electric field sensors 14a and 14d are positioned opposite each other in the circumferential direction. The electric field sensors 14b and 14e are positioned opposite each other in the circumferential direction. The electric field sensors 14c and 14f are positioned opposite each other in the circumferential direction.

[0082] The three electric field sensors 14a, 14b, and 14c are inserted into through-holes that penetrate the sidewall of processing vessel 1 from the outer surface of processing vessel 1, and are attached so that their tips are positioned along the inner surface of processing vessel 1 and exposed to waveguide 9. Electric field sensors 14a to 14c are exposed to waveguide 9 from the same direction. Similarly, electric field sensors 14d to 14f are attached so that they are exposed to waveguide 9 from the same direction. Since electric field sensor 14 is located close to plasma, it has heat resistance of 100°C or more. Electric field sensor 14 detects the electric field of the standing wave on the surface of waveguide 9.

[0083] [Effects of the third embodiment] In this way, the plasma processing apparatus 100B can detect the concentric electric field distribution of the standing wave propagating through the dielectric ring 7 by using three or more electric field sensors 14 in the vertical direction. Furthermore, the plasma processing apparatus 100B can detect the tilt of the mounting table 3 and the bias of the plasma by arranging electric field sensors 14 in the circumferential direction corresponding to at least one of the three or more electric field sensors 14 in the vertical direction.

[0084] Furthermore, the plasma processing apparatus 100B has a dielectric ring 7 having an effective wavelength λ of VHF. eff If there is not enough thickness to mount three or more electric field sensors 14 in the vertical direction within an area of ​​¼ of the dielectric ring 7, three or more electric field sensors 14 can be mounted on the waveguide 9 adjacent to the dielectric ring 7. This makes it possible to detect the concentric electric field distribution of the standing wave propagating through the waveguide 9.

[0085] Furthermore, by combining four or more circumferential electric field sensors 14 and three or more vertical electric field sensors 14, the state of plasma generated from the processing gas using high frequency power in the VHF or UHF band can be detected with even greater accuracy.

[0086] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0087] Furthermore, the following supplementary notes are disclosed regarding the above-described embodiment. <Additional Notes> (1) a processing chamber disposed within the processing vessel; a mounting table located within the processing chamber and on which a substrate is placed; an upper electrode facing the mounting table; a waveguide located along the upper electrode and through which high frequency power in the VHF band or UHF band propagates; a dielectric ring separating the processing chamber from the waveguide; four or more electric field sensors positioned in the circumferential direction of the dielectric ring; the four or more electric field sensors are arranged at positions such that, when a reference position is 0, the angles formed by a line connecting the center of the dielectric ring to one of the four or more electric field sensors and a line connecting the center of the dielectric ring to each of the four or more electric field sensors are represented by 0, (t1·π / 2+π / 6), (t2·π / 2+2π / 6), and (t3·π / 2+3π / 6), where t1, t2, and t3 are integers including 0. (2) t1, t2 and t3 are 0, The plasma processing apparatus according to (1), wherein the four or more electric field sensors are positioned in the circumferential direction at intervals of π / 6 within the area of ​​0 to π / 2 angles. (3) At least one of t1, t2, and t3 is 1 or greater; The plasma processing apparatus according to (1), wherein the four or more electric field sensors are positioned in the circumferential direction and distributed in two or more areas among the four areas where the angles are 0 to π / 2, π / 2 to π, π to 3π / 2, and 3π / 2 to 2π. (4) The plasma processing apparatus according to any one of (1) to (3), wherein four or more of the electric field sensors are in contact with the dielectric ring. (5) The plasma processing apparatus according to any one of (1) to (4), further comprising a control device that detects bias in the electric field distribution in the circumferential direction of the substrate based on sensor values ​​output from four or more of the electric field sensors. (6) the plasma processing apparatus further includes a high-frequency power supply connected to the mounting table and applying a bias voltage to the mounting table; The plasma processing apparatus according to (5), wherein the control device detects bias in the bias voltage based on sensor values ​​output from four or more of the electric field sensors. (7) a processing chamber disposed within the processing vessel; a mounting table located within the processing chamber and on which a substrate is placed; an upper electrode facing the mounting table; a waveguide located along the upper electrode and through which high frequency power in the VHF band or UHF band propagates; a dielectric ring separating the processing chamber from the waveguide; and three or more electric field sensors positioned along the propagation direction of the high frequency power propagating through the dielectric ring or the waveguide and arranged within an area of ​​¼ of the effective wavelength of the VHF or UHF band high frequency. (8) The plasma processing apparatus according to (7), wherein the three or more electric field sensors contact the dielectric ring from the same direction. (9) The plasma processing apparatus according to (7), wherein three or more of the electric field sensors are exposed to the waveguide from the same direction. (10) The plasma processing apparatus according to any one of (7) to (9), further comprising a control device that detects bias in the electric field distribution in the radial direction of the substrate based on sensor values ​​output from three or more of the electric field sensors. (11) further comprising an electric field sensor located in the circumferential direction of the dielectric ring with respect to at least one of the three or more electric field sensors, The plasma processing apparatus according to (10), wherein the control device detects the tilt of the mounting table based on sensor values ​​output from a plurality of electric field sensors positioned in a circumferential direction of the dielectric ring. [Explanation of symbols]

[0088] 1: Processing container 2: Lid 3: Mounting table 5:Top electrode 7: Dielectric ring 9: Waveguide 10: Matching box 11:VHF power supply 12:High frequency power supply 14: Electric field sensor 20: Control device 100, 100A, 100B: Plasma treatment device U: Processing room W: Substrate

Claims

1. a processing chamber disposed within the processing vessel; a mounting table located within the processing chamber and on which a substrate is placed; an upper electrode facing the mounting table; a waveguide located along the upper electrode and through which high frequency power in the VHF band or the UHF band propagates; a dielectric ring separating the processing chamber from the waveguide; four or more electric field sensors positioned in a circumferential direction of the dielectric ring, The four or more electric field sensors are configured such that, when a reference position is set to 0, an angle formed by a line connecting the center of the dielectric ring and one of the four or more electric field sensors and a line connecting the center of the dielectric ring and each of the four or more electric field sensors is within a range of 0 to (t １ ・π / 2+π / 6) and (t ２ ・π / 2+2π / 6) and (t ３ π / 2+3π / 6), and t １ , t ２ and t ３ is an integer including 0.

2. t １ , t ２ and t ３ is 0, 2. The plasma processing apparatus according to claim 1, wherein the four or more electric field sensors are positioned in the circumferential direction at intervals of π / 6 within the area of ​​0 to π / 2 angles.

3. t １ , t ２ and t ３ At least one of them is greater than or equal to 1, 2. The plasma processing apparatus according to claim 1, wherein the four or more electric field sensors are positioned in a circumferential direction and distributed in two or more of four areas where the angles are 0 to π / 2, π / 2 to π, π to 3π / 2, and 3π / 2 to 2π.

4. The plasma processing apparatus of claim 1 , wherein four or more of the electric field sensors contact the dielectric ring.

5. 5. The plasma processing apparatus according to claim 1, further comprising a control device that detects bias in the electric field distribution in the circumferential direction of said substrate based on sensor values ​​output from four or more of said electric field sensors.

6. the plasma processing apparatus further includes a high-frequency power supply connected to the mounting table and applying a bias voltage to the mounting table; 6. The plasma processing apparatus according to claim 5, wherein the control device detects the bias of the bias voltage based on sensor values ​​output from four or more of the electric field sensors.

7. a processing chamber disposed within the processing vessel; a mounting table located within the processing chamber and on which a substrate is placed; an upper electrode facing the mounting table; a waveguide located along the upper electrode and through which high frequency power in the VHF band or the UHF band propagates; a dielectric ring separating the processing chamber from the waveguide; and three or more electric field sensors positioned along the propagation direction of the high frequency power propagating through the dielectric ring or the waveguide and arranged within an area of ​​¼ of the effective wavelength of the VHF or UHF band high frequency.

8. The plasma processing apparatus according to claim 7 , wherein three or more of the electric field sensors contact the dielectric ring from the same direction.

9. The plasma processing apparatus according to claim 7 , wherein three or more of the electric field sensors are exposed to the waveguide from the same direction.

10. 10. The plasma processing apparatus according to claim 7, further comprising a control device that detects bias in the electric field distribution in the radial direction of the substrate based on sensor values ​​output from three or more of the electric field sensors.

11. further comprising an electric field sensor located in a circumferential direction of the dielectric ring with respect to at least any of the three or more electric field sensors; 11. The plasma processing apparatus according to claim 10, wherein the control device detects the tilt of the mounting table based on sensor values ​​output from a plurality of electric field sensors positioned in a circumferential direction of the dielectric ring.

Images