Plasma potential sensor

Abstract

To provide a plasma potential sensor capable of increasing flexibility in installing the same.SOLUTION: A disclosed plasma potential sensor 10 is a plasma potential sensor 10 that is configured to be attached to the inner wall of a chamber 103 provided in plasma processing equipment 100 for detecting the potential of plasma generated in the chamber 103. The plasma potential sensor 10 includes: a first main surface 11 that is attached to the inner wall of chamber 103; a second main surface 12 located on the opposite side of the first main surface 11 facing the plasma when in use: a plate-shaped conductive detection electrode 13; a signal leader line 14 connected to the detection electrode 13; a protective layer 15 that has insulation properties and covers the first main surface 11 side of each of the detection electrode 13 and the signal leader line 14.SELECTED DRAWING: Figure 2

Description

Technical Field

[0006] , ,

[0001] The present disclosure relates to a plasma potential sensor.

Background Art

[0002] In various processes for manufacturing electronic components and circuit boards, a plasma processing apparatus that generates plasma in a processing chamber to etch or clean the surface of an object to be processed is used. In order to determine whether plasma discharge is occurring normally in the processing chamber, there is a configuration in which a probe electrode for measuring plasma potential is provided on the side wall of the processing chamber. The probe electrode detects charges or potentials induced in response to changes in plasma discharge.

[0003] For example, in Patent Document 1, there is proposed a window-type probe having a conductive support member provided with an opening in at least a part of a surface facing plasma, and a dielectric member installed in the opening of the conductive support member, and a probe electrode provided on one side surface of the dielectric member.

[0004] The charges or potentials of the probe electrode are usually converted into digital values by an analog-digital converter (ADC), and it is determined whether abnormal discharge has occurred by mathematically processing the time-series data of the digital values.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the probe electrode (or plasma potential sensor) described in Patent Document 1 needs to be installed in the opening of the conductive support member, making it difficult to freely install it at any location within the processing chamber. In this situation, one of the objectives of this disclosure is to increase the degree of freedom in installing the plasma potential sensor. [Means for solving the problem]

[0007] One aspect of the present disclosure relates to a plasma potential sensor. The plasma potential sensor is configured to be attachable to the inner wall of a chamber provided by a plasma processing apparatus, and detects the potential of a plasma generated in the chamber, and comprises: a first main surface attached to the inner wall of the chamber; a second main surface located on the opposite side of the first main surface and facing the plasma during use; a conductive plate-shaped detection electrode; a signal lead wire connected to the detection electrode; and a protective layer that is insulating and covers the first main surface side of the detection electrode and the signal lead wire, respectively. [Effects of the Invention]

[0008] According to this disclosure, the degree of flexibility in installing plasma potential sensors can be increased. [Brief explanation of the drawing]

[0009] [Figure 1] This is a conceptual diagram showing a cross-sectional view of the schematic structure of an example of a plasma processing apparatus in which the plasma potential sensor according to this disclosure is used. [Figure 2] This figure shows a plasma potential sensor according to Embodiment 1, where (a) is a plan view and (b) is a cross-sectional view along line II-II. [Figure 3] This figure shows a plasma potential sensor according to Embodiment 2, where (a) is a plan view and (b) is a cross-sectional view along line III-III. [Figure 4] This figure shows a plasma potential sensor according to Embodiment 3, where (a) is a plan view and (b) is a cross-sectional view along line IV-IV. [Figure 5]This is a circuit diagram showing an example of a detection circuit connected to a plasma potential sensor according to Embodiment 3. [Modes for carrying out the invention]

[0010] An embodiment of the plasma potential sensor relating to this disclosure will be described below with examples. However, this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are obtained.

[0011] The plasma potential sensor according to this disclosure is configured to be attachable to the inner wall of a chamber in a plasma processing apparatus and detects the potential of the plasma generated in the chamber. The plasma processing apparatus may be, for example, a plasma etching apparatus, a plasma cleaning apparatus, a plasma dicer, a plasma ashing apparatus, or a plasma CVD apparatus. The plasma potential sensor according to this disclosure comprises a first main surface, a second main surface, a detection electrode, a signal lead line, and a protective layer.

[0012] The first main surface is a main surface attached to the inner wall of the chamber. The first main surface may be attached to the inner wall of the chamber by means of, for example, adhesive, bonding, or fitting. The first main surface may be exposed to the outside of the plasma potential sensor. The first main surface may or may not be flat.

[0013] The second principal surface is the principal surface located opposite the first principal surface. The second principal surface faces the plasma in the chamber when the plasma potential sensor is in use. The second principal surface may be exposed to the outside of the plasma potential sensor. The second principal surface may or may not be flat. The second principal surface may or may not be parallel to the first principal surface.

[0014] The detection electrode is a conductive plate-shaped electrode. The shape of the detection electrode may be, for example, a rectangular plate, but is not limited to this. The detection electrode may be made of the same material as the material that makes up the inner wall of the chamber (e.g., aluminum or stainless steel), or it may be made of other conductive material (e.g., copper or aluminum). When using the plasma potential sensor, the detection electrode can induce a charge corresponding to the potential of the plasma generated in the chamber.

[0015] The signal lead wire is connected to the detection electrode. The signal lead wire may be conductive. The constituent material of the signal lead wire may be the same as or different from the constituent material of the detection electrode. The signal lead wire may be integrated with or separate from the detection electrode. The signal lead wire may be narrower than the detection electrode when viewed from a direction perpendicular to the surface of the detection electrode. The signal lead wire may be connected to an electrical circuit that processes the signal of the charge induced at the detection electrode, for example.

[0016] The protective layer is insulating. The protective layer may be made of, for example, glass or an insulating resin. The protective layer covers the first main surface side of each of the detection electrode and the signal lead wire. The outer surface of the protective layer may constitute the first main surface of the plasma potential sensor. The protective layer may have a shape that conforms to the outer shape of each of the detection electrode and the signal lead wire.

[0017] A plasma potential sensor having the above configuration can be mounted in any available space on the inner wall (or side wall) of the chamber of a plasma processing apparatus in order to detect the potential of the plasma generated within the chamber. Therefore, the plasma potential measurement position can be set according to the user's requirements without changing the configuration of the plasma processing apparatus.

[0018] The protective layer may also cover the second major surface sides of each of the detection electrode and the signal lead-out wire. At this time, the outer surface of the protective layer may constitute the second major surface of the plasma potential sensor. In this configuration, the surfaces of the detection electrode and the signal lead-out wire facing the plasma are covered by the protective layer. Therefore, the detection electrode and the signal lead-out wire can be protected from the plasma.

[0019] The plasma potential sensor may further include an auxiliary electrode provided inside the protective layer on the second major surface side of the signal lead-out wire, covering at least a part of the signal lead-out wire when viewed from the second major surface side, and being electrically insulated from the signal lead-out wire. By providing such an auxiliary electrode, mutual interference between the plasma and the signal lead-out wire can be suppressed. Specifically, the influence of the charge signal induced in the detection electrode by the influence from the plasma to the signal lead-out wire and the influence on the state of the plasma by the influence from the signal lead-out wire to the plasma are suppressed by the auxiliary electrode. A predetermined voltage may be applied to the auxiliary electrode. The predetermined voltage may be, for example, the same as the voltage applied to the side wall of the chamber, or may be a ground voltage.

[0020] The detection electrode may be exposed to the outside on the second major surface side. At this time, the surface of the detection electrode constitutes the second major surface of the plasma potential sensor. The detection electrode is preferably made of the same material as the constituent material of the inner wall of the chamber. In this case, when viewed from inside the chamber (or from the plasma side), the detection electrode behaves as if it were a part of the inner wall of the chamber. Therefore, in the installation area of the plasma potential sensor, it is possible to suppress a local influence on the plasma caused by the sensor.

[0021] The plasma potential sensor may further include a guard electrode provided inside the protective layer on the first major surface side of the detection electrode and the signal lead-out wire, covering the detection electrode and the signal lead-out wire when viewed from the first major surface side, and being electrically insulated from the detection electrode and the signal lead-out wire. By providing such a guard electrode, the influence of the back capacitance formed between the detection electrode and the inner wall of the chamber can be reduced, and the detection accuracy of the plasma potential sensor can be improved.

[0022] The guard electrode may be virtually short-circuited with the detection electrode. According to this configuration, the potential of the detection electrode and the potential of the guard electrode become equal to each other, and the flow of charge between the above-mentioned back capacitance and the detection electrode is suppressed. Therefore, almost all of the charges induced in the detection electrode can be sent to the signal lead wire and thus to an electric circuit or the like connected to the end thereof, and the detection accuracy of the plasma potential sensor can be further enhanced.

[0023] Note that the guard electrode being virtually short-circuited with the detection electrode means that the potential of the guard electrode is controlled to be the same as that of the detection electrode with respect to the potential variation of the detection electrode. However, different from a normal short circuit, it is not necessarily the case that current flows from the detection electrode toward the guard electrode or from the guard electrode toward the detection electrode, and the current flowing through the detection electrode can be controlled independently of the current flowing through the guard electrode.

[0024] The guard electrode may be virtually short-circuited with the detection electrode via an operational amplifier. The operational amplifier may include a current mirror circuit configured by combining a plurality of transistors. The operational amplifier may be composed of an IC chip commercially available as a general operational amplifier circuit.

[0025] As described above, according to the present disclosure, the freedom in installing the plasma potential sensor can be enhanced. Furthermore, according to the present disclosure, it is possible to enhance the detection accuracy of the plasma potential sensor.

[0026] Hereinafter, an example of a plasma potential sensor according to this disclosure will be specifically described with reference to the drawings. The components of the example plasma potential sensor described below can be the components described above. The components of the example plasma potential sensor described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiments. Among the components of the example plasma potential sensor described below, components that are not essential to the plasma potential sensor according to this disclosure may be omitted. Note that the figures shown below are schematic and do not accurately reflect the actual shape and number of components.

[0027] Embodiment 1 Embodiment 1 of this disclosure will now be described. The plasma potential sensor 10 of this embodiment is used in a plasma processing apparatus 100 that generates plasma, which is the target of plasma potential detection. Below, the plasma processing apparatus 100 will be described first, followed by the plasma potential sensor 10.

[0028] (Plasma treatment device) The plasma processing apparatus comprises a processing chamber, an electrode section provided in the processing chamber on which the object to be processed is placed, and a high-frequency power supply section that applies high-frequency power to the electrode section. When plasma generating gas is supplied to the processing chamber and high-frequency power is applied to the electrode section, plasma is generated in the processing chamber. The generated plasma can be used, for example, for etching or cleaning the surface of the object to be processed placed on the electrode section. The plasma processing apparatus is connected to a detection circuit for detecting the plasma potential. The output of the detection circuit is connected to a signal analysis unit. The signal analysis unit detects the plasma potential based on the output of the detection circuit and determines whether the generated plasma is normal or not based on the detected plasma potential.

[0029] Figure 1 is a conceptual diagram showing a cross-sectional view of the schematic structure of a plasma processing apparatus 100 in which plasma, the target of plasma potential detection, is generated. The processing chamber 103a is formed by sealing a chamber (vacuum chamber) 103, which is composed of a horizontal base portion 101 and a lid portion 102. The lid portion 102 is arranged to be able to move up and down by a lifting mechanism (not shown). When the lid portion 102 descends and comes into contact with the upper surface of the base portion 101, the chamber 103 becomes sealed. At this time, a sealing member 104 is interposed between the lid portion 102 and the base portion 101, thereby ensuring that the processing chamber 103a is sealed. In the processing chamber 103a, the object to be processed 109 is subjected to plasma processing. An opening 101a is provided in the base portion 101, and an electrode portion 105 is fitted in via an insulating member 106 so as to close the opening 101a. The upper surface of the electrode portion 105 is covered with an insulating layer 107. A guide member 108 for positioning the object to be processed 109 is positioned on the upper surface of the insulating layer 107.

[0030] A through hole 101b is formed around the periphery of the opening 101a of the base portion 101. A conduit 111 is inserted into the through hole 101b, and a vent valve 112, a gas supply valve 113, a vacuum valve 114, and a vacuum gauge 115 are connected to the conduit 111. A gas supply unit 116 and a vacuum pump 117 are further connected to the gas supply valve 113 and the vacuum valve 114, respectively. By opening the vacuum valve 114 and operating the vacuum pump 117, the gas in the processing chamber 103a is discharged, creating a reduced pressure state. The vacuum level in the processing chamber 103a is measured by the vacuum gauge 115. On the other hand, when the gas supply valve 113 is opened, plasma generation gas is supplied to the processing chamber 103a from the gas supply unit 116. The gas supply unit 116 has a built-in flow rate adjustment mechanism, which adjusts the flow rate of the plasma generation gas supplied to the processing chamber 103a. When the vent valve 112 is opened, air is supplied into the processing chamber 103a.

[0031] The electrode section 105 is electrically connected to the high-frequency power supply section 119 via a matching unit 118. Meanwhile, the lid section 102 is grounded to the grounding section 110. When plasma generation gas is supplied into the processing chamber 103a and the high-frequency power supply section 119 is operated, a high-frequency voltage is applied between the electrode section 105 and the lid section 102. This generates plasma in the processing chamber 103a. The matching unit 118 matches the impedance between the plasma discharge circuit (not shown) that generates the plasma and the high-frequency power supply section 119. The vent valve 112, gas supply valve 113, vacuum valve 114, vacuum gauge 115, gas supply section 116, vacuum pump 117, and high-frequency power supply section 119 are controlled by the device control section 124 within the control unit 120. That is, the device control section 124 has a normal operation control function to execute the plasma processing operation. The control unit 120 is connected to the display section 130, the input section 140, and the detection circuit 200. The display unit 130 shows the results of the abnormality detection performed by the signal analysis unit 121, which will be described later. The input unit 140 receives input such as the process recipe.

[0032] In this example, a plasma potential sensor 10 is attached to the inner wall (side wall) of the chamber 103 by adhesive. The configuration of the plasma potential sensor 10 will be described in detail later. The plasma potential sensor 10 and the detection circuit 200 constitute a plasma potential measuring device.

[0033] When a plasma discharge occurs in the processing chamber 103a, a potential and charge corresponding to the state of the plasma are induced in the detection electrode 13 (described later) of the plasma potential sensor 10. The charge induced in the detection electrode 13 is sent as an analog signal to the detection circuit 200, where it is converted into a digital signal or amplified. The digital signal or amplified analog signal is sent to the signal analysis unit 121 of the control unit 120. Based on the received signal, the signal analysis unit 121 determines whether the state of the plasma is normal or not. If it is determined that the state of the plasma is not normal and is in an abnormal discharge state, retry processing, cumulative plasma processing, maintenance determination, etc., may be performed. Note that it is not necessary for all of the retry processing, cumulative plasma processing, and maintenance determination to be performed; one or more of these processes may be performed.

[0034] The device control unit 124, although not shown in the figures, may also include a processing history storage unit, a retry processing unit, an accumulated plasma processing unit, and a maintenance determination function unit. That is, in addition to the normal operation control functions described above, the device control unit 124 can determine the state of plasma discharge in the processing chamber 103a based on the abnormal discharge detection result by the signal analysis unit 121 and reset the plasma processing. The determination of the plasma discharge state and the resetting of the plasma processing can be performed by the retry processing unit, the accumulated plasma processing unit, and the maintenance determination unit. The processing history storage unit stores the time change of the signal from the detection circuit 200, which is temporarily recorded in memory, and the intermediate data required by the signal analysis unit 121 to determine the detection of abnormal discharge, as processing history data from the plasma processing device 100. This makes it possible to obtain detailed processing history data for the object 109 processed by the plasma processing device 100, ensuring traceability for quality control and production control.

[0035] (Plasma potential sensor) The plasma potential sensor 10 is a device for detecting the potential of the plasma generated in the chamber 103 of the plasma processing apparatus 100. The plasma potential sensor 10 may have enough flexibility to deform along the shape of the inner wall of the chamber 103. As shown in Figure 2, the plasma potential sensor 10 comprises a first main surface 11, a second main surface 12, a detection electrode 13, a signal lead line 14, and a protective layer 15.

[0036] The first main surface 11 is a main surface attached to the inner wall of the chamber 103. In this embodiment, the first main surface 11 is attached to the inner wall of the chamber 103 by adhesive, but is not limited to this. The first main surface 11 is exposed to the outside of the plasma potential sensor 10. The first main surface 11 is flat.

[0037] The second main surface 12 is a main surface located on the opposite side of the first main surface 11. The second main surface 12 faces the plasma in the chamber 103 when the plasma potential sensor 10 is in use. The second main surface 12 is exposed to the outside of the plasma potential sensor 10. The second main surface 12 is flat. The second main surface 12 is parallel to the first main surface 11.

[0038] The detection electrode 13 is a conductive rectangular plate-shaped electrode. When the plasma potential sensor 10 is used, the detection electrode 13 can induce a charge corresponding to the potential of the plasma generated in the chamber 103. The signal of the induced charge is sent to the detection circuit 200 via the signal lead line 14.

[0039] The signal lead wire 14 is connected to the detection electrode 13. The signal lead wire 14 is formed integrally with the detection electrode 13 and is conductive. As shown in Figure 2(a), the signal lead wire 14 is narrower than the detection electrode 13 when viewed from a direction perpendicular to the surface of the detection electrode 13. The width of the signal lead wire 14 may be, for example, 10% or more and 30% or less of the width of the detection electrode 13. The thickness of the signal lead wire 14 is equal to the thickness of the detection electrode 13, as shown in Figure 2(b), but is not limited to this. The signal lead wire 14 may have a connection portion (not shown) that is electrically connected to the detection circuit 200. This connection portion may be exposed to the outside of the plasma potential sensor 10.

[0040] The protective layer 15 is insulating. In this embodiment, the protective layer 15 is made of glass, but is not limited to this. The protective layer 15 covers the first main surface 11 side of each of the detection electrode 13 and the signal lead line 14. The protective layer 15 has a shape that conforms to the outer shape of each of the detection electrode 13 and the signal lead line 14. The protective layer 15 also covers the second main surface 12 side of each of the detection electrode 13 and the signal lead line 14. However, although not shown in the figures, the protective layer 15 does not have to cover the second main surface 12 side of each of the detection electrode 13 and the signal lead line 14. In other words, the detection electrode 13 and the signal lead line 14 may be exposed to the outside on the second main surface 12 side.

[0041] Embodiment 2 Embodiment 2 of this disclosure will now be described. The plasma potential sensor 10 of this embodiment differs from Embodiment 1 in that it includes an auxiliary electrode 16. The differences from Embodiment 1 will be mainly described below.

[0042] As shown in Figure 3, the plasma potential sensor 10 includes an auxiliary electrode 16 provided on the second main surface 12 side of the signal lead wire 14. The auxiliary electrode 16 is provided inside the protective layer 15 on the second main surface 12 side of the signal lead wire 14, and covers at least a portion of the signal lead wire 14 when viewed from the second main surface 12 side, while being insulated from the signal lead wire 14. As shown in Figure 3(a), the auxiliary electrode 16 is wider than the signal lead wire 14 when viewed from a direction perpendicular to the surface of the detection electrode 13. The width of the auxiliary electrode 16 may be, for example, 100% or more and 150% or less of the width of the signal lead wire 14. A ground voltage may be applied to the auxiliary electrode 16, for example, by being electrically connected to the cover portion 102. The auxiliary electrode 16 does not have to cover the detection electrode 13 when viewed from the second main surface 12 side.

[0043] Embodiment 3 Embodiment 3 of this disclosure will now be described. The plasma potential sensor 10 of this embodiment differs from Embodiment 1 in that it includes a guard electrode 17. The differences from Embodiment 1 will be mainly described below.

[0044] As shown in Figure 4, the plasma potential sensor 10 includes a guard electrode 17 provided on the first main surface 11 side of the detection electrode 13. The guard electrode 17 is provided on the first main surface 11 side of both the detection electrode 13 and the signal lead wire 14, and covers the entire detection electrode 13 and the signal lead wire 14 as viewed from the first main surface 11 side, while being electrically insulated from both.

[0045] As shown in Figure 5, the detection circuit 200 comprises a first operational amplifier 202 and a second operational amplifier 204. The guard electrode 17 is virtually short-circuited with the detection electrode 13 via the first operational amplifier 202. The first operational amplifier 202 is an example of an operational amplifier.

[0046] The non-inverting input terminal of the first operational amplifier 202 is connected to the detection electrode 13 via wiring 151 and signal lead line 14. The output terminal of the first operational amplifier 202 is connected to the guard electrode 17 via wiring 152. The output terminal of the first operational amplifier 202 is also connected to the inverting input terminal of the first operational amplifier 202 without a feedback resistor. As a result, the first operational amplifier 202 constitutes a non-inverting amplifier circuit with a gain of 1, and the detection electrode 13 connected to the non-inverting input terminal of the first operational amplifier 202 and the guard electrode 17 connected to the inverting input terminal of the first operational amplifier 202 are virtually short-circuited.

[0047] Due to the virtual short-circuit effect of the operational amplifier, the potential of the inverting input terminal of the first operational amplifier 202 connected to the guard electrode 17 operates to be the same as the potential of the non-inverting input terminal of the first operational amplifier 202 connected to the detection electrode 13.

[0048] The inverting input terminal of the second operational amplifier 204 is connected to the signal lead line 14 (detection electrode 13) via resistor R1. The non-inverting input terminal of the second operational amplifier 204 is grounded. The output terminal of the second operational amplifier 204 is connected to the inverting input terminal of the second operational amplifier 204 via feedback resistor R2. As a result, the second operational amplifier 204 forms an inverting amplifier circuit, and the amplified voltage of the potential of the detection electrode 13 is output to the output terminal of the second operational amplifier 204. The output voltage is sent to the signal analysis unit 121 of the control unit 120.

[0049] In the second operational amplifier 204, a capacitor C1 (not shown) may be connected between the output terminal and the inverting input terminal instead of the feedback resistor R2. In this case, the second operational amplifier 204 constitutes an integrating circuit, amplifying the amount of charge induced at the detection electrode 13, and a voltage corresponding to the amplified amount of charge is output to the output terminal. [Industrial applicability]

[0050] This disclosure can be used in plasma potential sensors. [Explanation of Symbols]

[0051] 10: Plasma potential sensor 11: First main surface 12: Second main surface 13: Detection electrode 14: Signal lead wire 15:Protective layer 16:Auxiliary electrode 17: Guard electrode 100: Plasma processing equipment 101: Base section 101a: Opening 101b: Through hole 102: Lid part 103: Chamber 103a: Processing Room 104: Sealing material 105: Electrode part 106: Insulating material 107: Insulating layer 108: Guide member 109: Object to be processed 110: Grounding part 111: Pipeline 112: Vent valve 113: Gas supply valve 114: Vacuum valve 115: Vacuum gauge 116: Gas Supply Department 117: Vacuum pump 118: Matching box 119: High frequency power supply section 120: Control Unit 121: Signal analysis section 124: Device Control Unit 130: Display section 140: Input section 151,152: Wiring 200: Detection circuit 202: First operational amplifier (operational amplifier) 204: Second operational amplifier

Claims

1. A plasma potential sensor configured to be attachable to the inner wall of a chamber in a plasma processing apparatus, for detecting the potential of the plasma generated in the chamber, A first main surface attached to the inner wall of the chamber, A second main surface located on the opposite side of the first main surface and facing the plasma during use, A conductive plate-shaped detection electrode, A signal lead wire connected to the detection electrode, A protective layer that is insulating and covers the first main surface side of each of the detection electrode and the signal lead line, Equipped with, The protective layer also covers the second main surface side of each of the detection electrode and the signal lead line. A plasma potential sensor further comprising an auxiliary electrode provided inside the protective layer on the second main surface side of the signal lead wire, electrically insulated from the signal lead wire, and covering at least a portion of the signal lead wire as viewed from the second main surface side.

2. A plasma potential sensor configured to be attachable to the inner wall of a chamber of a plasma processing apparatus, for detecting the potential of plasma generated in the chamber, A first main surface attached to the inner wall of the chamber, A second main surface located on the opposite side of the first main surface and facing the plasma during use, A conductive plate-shaped detection electrode, A signal lead wire connected to the detection electrode, A protective layer that is insulating and covers the first main surface side of each of the detection electrode and the signal lead line, Equipped with, The detection electrode is a plasma potential sensor that is exposed to the outside on the second main surface side.

3. A plasma potential sensor configured to be attachable to the inner wall of a chamber of a plasma processing apparatus, for detecting the potential of plasma generated in the chamber, A first main surface attached to the inner wall of the chamber, A second main surface located on the opposite side of the first main surface and facing the plasma during use, A conductive plate-shaped detection electrode, A signal lead wire connected to the detection electrode, A protective layer that is insulating and covers the first main surface side of each of the detection electrode and the signal lead line, Equipped with, A plasma potential sensor further comprising a guard electrode provided inside the protective layer on the first main surface side of the detection electrode and the signal lead wire, which is electrically insulated from the detection electrode and the signal lead wire and covers the detection electrode and the signal lead wire when viewed from the first main surface side.

4. The plasma potential sensor according to claim 3, wherein the guard electrode is virtually short-circuited with the detection electrode.

5. The plasma potential sensor according to claim 4, wherein the guard electrode is virtually short-circuited with the detection electrode via an operational amplifier.

6. A plasma potential sensor configured to be attachable to the inner wall of a chamber in a plasma processing apparatus, for detecting the potential of the plasma generated in the chamber, A first main surface is attached to the inner wall of the chamber by being glued, A second main surface located on the opposite side of the first main surface and facing the plasma during use, A conductive plate-shaped detection electrode, A signal lead wire connected to the detection electrode, A protective layer made of insulating resin, which has insulating properties and covers the first main surface side of each of the detection electrode and the signal lead line, Equipped with, A plasma potential sensor having flexibility that allows it to deform along the inner wall of the chamber.

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