A plasma processing device

Abstract

This invention discloses a plasma processing device, including a process cavity and a radio frequency (RF) cavity. The process cavity contains a base supporting a substrate, and the RF cavity contains an RF component connected to an RF source to excite plasma. The RF cavity also contains a valve assembly, the outlet of which is directly connected to the inlet of the process cavity to shorten the gas path length. The valve assembly includes a valve body and a fiber optic position detection unit. The fiber optic position detection unit includes an fiber optic unit and a fiber optic amplifier. The fiber optic unit is mounted on the valve body to detect the valve's open / closed state, and the fiber optic amplifier is located outside the RF cavity. This invention uses fiber optic position detection to replace traditional electromagnetic sensors, utilizing the characteristic that optical signal transmission is unaffected by electromagnetic interference. This fundamentally solves the problem of strong electromagnetic fields in the RF cavity interfering with valve position detection, ensuring stable detection without electromagnetic shielding, reducing the failure rate, and improving equipment reliability and operational stability.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor manufacturing technology, and specifically to a plasma processing device. Background Technology

[0002] In plasma processing equipment, the location of the inlet valve affects the inlet response speed. To improve the inlet response speed, one approach is to shorten the flow path at the rear end of the inlet valve and install it closer to the process chamber. Another approach, to reduce the space occupied by the inlet valve, is to place it within the radio frequency chamber. However, after a period of operation, it was found that the failure rate of the inlet valve was higher than the baseline value. Therefore, how to improve the service life of the inlet valve while shortening the gas path length by placing the valve assembly closer to the process chamber has become a pressing issue. Utility Model Content

[0003] To solve the above problems, the present invention adopts the following technical solution: A plasma processing device includes a process cavity and a radio frequency (RF) cavity. The process cavity contains a base to support a substrate, and the RF cavity contains an RF component electrically connected to an RF source. The RF source feeds RF energy into the process cavity through the RF component to excite plasma within the process cavity to process the substrate. The RF cavity also contains a valve assembly, the outlet of which is connected to the inlet of the process cavity. The valve assembly includes a valve body and a fiber optic position detection unit. The fiber optic position detection unit includes an fiber optic unit and a fiber optic amplifier. The fiber optic unit is mounted on the valve body and is used to detect the valve's open / closed state. The fiber optic amplifier is located outside the RF cavity.

[0004] This invention directly places the valve assembly inside the radio frequency cavity, with the outlet of the valve assembly directly connected to the inlet of the process cavity. This significantly shortens the gas path length between the valve assembly and the process cavity, eliminating intermediate connecting pipes. This allows gas to quickly enter the process cavity after the valve is opened and to be quickly cut off after the valve is closed, thus achieving rapid gas supply switching and meeting the stringent requirements of advanced processes such as atomic layer etching and atomic layer deposition for gas switching rates.

[0005] Furthermore, this invention abandons the traditional electromagnetic position sensor solution and adopts a fiber optic position detection unit. Utilizing the physical characteristic that optical signals are completely unaffected by electromagnetic interference when transmitted through optical fibers, it fundamentally eliminates the influence of radio frequency electromagnetic fields on the position detection signal. The fiber optic unit does not rely on electronic circuits for detection; it is purely optical. Even when fully exposed to strong radio frequency electromagnetic fields, it will not be affected by any interference. The detection signal is transmitted through the optical fiber to a fiber optic amplifier located outside the radio frequency cavity for processing. All susceptible electronic components in the entire detection chain are kept away from radio frequency interference sources, thus achieving stable and reliable detection of the valve position within the radio frequency cavity without the need for any electromagnetic shielding structure. This improves detection reliability, reduces the valve assembly failure rate, and simplifies the equipment structure. Compared to electromagnetic shielding methods, it reduces the number of parts, lowers manufacturing costs, and reduces maintenance difficulty.

[0006] The radio frequency (RF) component includes an RF coil, with a hermetically sealed dielectric window separating the process cavity and the RF cavity. This structure is suitable for inductively coupled plasma (ICP) or transformer-coupled plasma (VCP) processing equipment, where the RF coil couples RF energy into the process cavity through the dielectric window to generate plasma. By placing the valve assembly within the RF cavity of this structure and employing a fiber optic position detection unit, interference from the high-intensity alternating electromagnetic field generated by the RF coil on position detection can be completely avoided.

[0007] The valve assembly includes a first valve arranged around the radio frequency coil. The first valve is arranged circumferentially around the radio frequency coil, which facilitates the uniform distribution of multiple valve assemblies and helps to achieve uniform gas distribution within the process chamber.

[0008] The valve assembly includes a second valve located inside the RF coil. This second valve, positioned in the central region of the RF coil, allows for central gas supply, further shortening the gas path length and improving the response speed of gas supply switching. This central gas supply scheme is particularly suitable for process scenarios requiring prioritized gas supply to the central region of the substrate or the formation of a centrally symmetrical gas flow field.

[0009] The radio frequency (RF) component includes an upper electrode, which hermetically isolates the process cavity and the RF cavity. This structure is suitable for capacitively coupled plasma (FCP) processing equipment, where the upper electrode acts as one plate of a capacitor, forming a capacitive coupling with the base. RF energy is fed into the process cavity to excite and generate CCP plasma. By placing the valve assembly within the RF cavity of this structure and employing a fiber optic position detection unit, interference from the strong alternating electric field generated by the upper electrode on position detection can be completely avoided.

[0010] The valve body comprises a pneumatic diaphragm valve, which includes a valve stem and a diaphragm. Driven by an actuator, the valve stem moves the diaphragm to open and close the valve. The pneumatic diaphragm valve offers excellent response speed, achieving millisecond-level opening and closing, making it particularly suitable for the rapid gas switching requirements of atomic layer processes. The diaphragm is made of a nickel-cobalt alloy, exhibiting excellent fatigue resistance and corrosion resistance.

[0011] The fiber optic unit includes a transmitter and a receiver, which are located on opposite sides of the valve stem's movement path. A light-shielding plate is mounted on the valve stem. As the valve stem moves to different positions, the light-shielding plate blocks or opens the optical path to detect the valve's open / closed state. This through-beam fiber optic detection solution is simple and reliable in structure, with no mechanical contact, no wear, and a long service life. The light-shielding plate moves synchronously with the valve stem, ensuring accurate positioning and high detection precision, enabling precise determination of whether the valve has reached the predetermined open or closed position.

[0012] The fiber optic unit employs a reflective detection structure, with its end facing the reflective surface on the valve stem. The valve's open / closed state is detected by sensing changes in the intensity of the reflected light. This reflective approach requires only a single fiber, resulting in less installation space and making it particularly suitable for space-constrained applications. The reflective surface can be directly machined onto the valve stem or diaphragm, eliminating the need for additional light-shielding components and further simplifying the structure.

[0013] The fiber optic unit is connected to the fiber optic amplifier via fiber optic cables, which pass through a sealed connector on the RF cavity housing and extend to the outside of the RF cavity.

[0014] The process chamber is equipped with an air intake ring that surrounds the sidewalls of the chamber. The air intake ring has multiple air inlets, and the valve assembly includes multiple air intake valves, which are installed on the air intake ring and correspond one-to-one with each air inlet. This structure minimizes air intake delay and ensures uniform gas distribution within the process chamber, improving the uniformity of the process. Furthermore, since each air inlet corresponds to an independent air intake valve, independent control of the air intake volume in different areas can be achieved, further enhancing the flexibility and precision of the process. Each air intake valve is equipped with an independent fiber optic position detection unit, and all detection signals are collected via their respective fiber optic cables to an external fiber optic amplifier array for centralized processing.

[0015] This invention directly places the valve assembly within the radio frequency cavity, with its outlet directly connected to the inlet of the process cavity. This eliminates intermediate connecting pipes, significantly shortening the gas path length and enabling rapid gas supply switching. This meets the gas switching rate requirements of advanced processes such as atomic layer etching and atomic layer deposition. By replacing traditional electromagnetic sensors with fiber optic position detection units, the invention leverages the physical characteristic that optical signals are completely unaffected by electromagnetic interference during transmission in optical fibers. This fundamentally eliminates the influence of strong electromagnetic fields within the radio frequency cavity on the position detection signal. The stability of the detection signal can be guaranteed without any electromagnetic shielding structure, significantly reducing the valve failure rate. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope of this utility model. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the plasma processing device in one embodiment of the present invention; Figure 2 This is an enlarged schematic diagram of the valve assembly in one embodiment of the present invention; Figure 3 This is a schematic diagram of the plasma processing device in another embodiment of the present invention; Figure 4 This is a schematic diagram of the plasma processing device in another embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: W-Substrate, 1-Process cavity, 2-RF cavity, 21-Housing, 3-Base, 4-RF component, 5-RF source, 6-Valve assembly, 6a-First valve, 6b-Second valve, 8-Dielectric window, 9-Upper electrode, 10-Inlet ring, 11-Inlet port, 20-Exhaust port, 41-RF coil, 42-RF feed rod, 61-Valve body, 62-Fiber optic unit, 63-Fiber optic amplifier, 64-Fiber optic cable, 65-Sealed connector. Detailed Implementation

[0019] The specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings. The technical solution of this utility model can be implemented in many different forms and is not limited to the specific embodiments described herein. The purpose of providing these specific embodiments is to enable a more thorough and comprehensive understanding of the disclosure of this utility model.

[0020] This invention fully utilizes the space of the radio frequency cavity by placing the intake valve inside the cavity, avoiding the extra radial space occupation caused by the intake valve protruding from the cavity. However, this leads to a new problem: the failure rate of the intake valve is found to be higher than the benchmark value.

[0021] Research revealed that the primary cause of the increased intake valve failure rate is electromagnetic interference. The intake valve is installed within a radio frequency (RF) cavity, where the RF components generate high-intensity RF electromagnetic fields during operation, reaching strengths of hundreds of volts per meter. This strong alternating electromagnetic field causes severe electromagnetic interference to nearby electronic components.

[0022] Traditional intake valves commonly employ electromagnetic position detection solutions, including Hall effect sensors, inductive proximity switches, and photoelectric sensors. These sensors all contain sensitive electronic circuit components, such as Hall effect elements, operational amplifiers, comparators, and signal conditioning circuits. In strong radio frequency electromagnetic fields, these electronic components are severely interfered with: First, the electromagnetic field induces high-frequency noise voltage on the sensor's signal lines, causing signal distortion and incorrect switching status signals; second, the strong electromagnetic field may directly couple into the sensor's internal circuitry, causing the circuit's operating point to shift, resulting in malfunctions or even lock-up; in the most severe cases, the high-frequency induced voltage may exceed the electronic components' withstand voltage limit, causing permanent physical damage.

[0023] To effectively avoid electromagnetic interference from radio frequency electromagnetic fields on valve assemblies while shortening the gas path length by placing valve assemblies close to the process cavity, this invention provides a plasma processing device using fiber optic position detection. This device replaces traditional electromagnetic sensors with fiber optic position detection units, utilizing the physical characteristic that fiber optic signal transmission is unaffected by electromagnetic interference. This fundamentally solves the problem of interference from strong electromagnetic fields in the radio frequency cavity on valve position detection. The stability of the detection signal can be guaranteed without additional electromagnetic shielding structures, significantly reducing the valve assembly failure rate. At the same time, it simplifies the equipment structure and reduces manufacturing costs.

[0024] like Figure 1 As shown, in one embodiment, the plasma processing equipment mainly includes two parts: a process chamber 1 and a radio frequency chamber 2. The process chamber 1 is a sealed space for plasma processing. Generally, the process chamber 1 has an exhaust port 20 for connecting a vacuum pumping component to maintain a vacuum state in the process chamber 1 during the process. A base 3 is provided inside the process chamber 1 to support the substrate W to be processed. In some embodiments, the base 3 may also be equipped with a heating unit, a rotation drive mechanism, or a bias radio frequency feed structure according to process requirements to achieve functions such as heating, rotating, or applying bias radio frequency power to the substrate W.

[0025] The radio frequency (RF) cavity 2 is arranged adjacent to the process cavity 1. In this embodiment, the RF cavity 2 is located above the process cavity 1. In other embodiments, the RF cavity 2 can also be arranged on the side of the process cavity 1 according to the overall layout requirements of the equipment. The valve assembly 6 is arranged inside the RF cavity 2, and the outlet end of the valve assembly 6 is directly connected to the inlet 11 of the process cavity 1, completely eliminating intermediate connecting pipes and minimizing the gas path length. Compared with the traditional remote installation scheme of the inlet valve, the shortening of the gas path length in this embodiment directly leads to an increase in gas switching speed.

[0026] The RF cavity 2 houses an RF component 4, which is electrically connected to an external RF source 5 via an RF feed rod 42. The RF energy generated by the RF source 5 is fed into the process cavity 1 through the RF component 4, ionizing the process gas within the process cavity 1 to generate plasma, thereby performing plasma processing processes such as etching and deposition on the substrate W. The output power of the RF source 5 is typically several hundred watts to several kilowatts, and the electromagnetic field strength generated inside the RF cavity 2 can reach several hundred volts per meter.

[0027] A valve assembly 6 is installed within the RF cavity 2. This valve assembly 6 controls the on / off state and flow rate of the process gas. Because the valve assembly 6 is directly located within the RF cavity 2, its outlet is directly connected to the inlet 11 of the process cavity 1, thus minimizing intermediate gas paths. When the valve assembly 6 is open, the process gas can quickly enter the process cavity 1 through the inlet 11; when the valve assembly 6 is closed, the gas supply can be quickly cut off, leaving no residual gas and not affecting subsequent processes. This rapid gas supply switching capability is beneficial for improving the process efficiency and yield of processes such as atomic layer etching and atomic layer deposition.

[0028] like Figure 2 As shown, valve assembly 6 includes a valve body 61 and a fiber optic position detection unit. The fiber optic position detection unit includes a fiber optic unit 62 and a fiber optic amplifier 63. The fiber optic unit 62 is mounted on the valve body 61 and is used to detect the valve's open / closed state. The fiber optic unit 62 does not rely on electronic circuitry for detection; it uses purely optical detection and is therefore completely unaffected by radio frequency electromagnetic fields. It can operate normally even when directly exposed to a strong electromagnetic field. The fiber optic unit 62 is connected to the fiber optic amplifier 63 via a fiber optic cable 64. The fiber optic cable 64 passes through a sealed connector 65 on the housing 21 of the radio frequency cavity 2 and extends to the outside of the radio frequency cavity 2. The fiber optic amplifier 63 is located in an electrical control cabinet outside the radio frequency cavity 2, and all electronic circuits operate in an interference-free environment.

[0029] like Figure 1As shown, in one embodiment, the RF component 4 includes an RF coil 41, and the process cavity 1 and the RF cavity 2 are hermetically separated by a dielectric window 8. The dielectric window 8 is made of an insulating material that allows the RF electromagnetic field to pass through. In some embodiments, the dielectric window 8 may be made of quartz, ceramic, or other suitable insulating materials. The dielectric window 8 also ensures the vacuum seal of the process cavity 1. The alternating electromagnetic field generated by the RF coil 41 is coupled into the process cavity 1 through the dielectric window 8, ionizing the process gas in the process cavity 1 and generating inductively coupled plasma or transformer-coupled plasma. When the RF coil 41 is operating, the intensity of the alternating electromagnetic field generated around it is the highest. Traditional electromagnetic sensors installed in this area are susceptible to interference, while fiber optic detection schemes have relatively high detection accuracy in this area.

[0030] like Figure 1 As shown, in one embodiment, the valve assembly includes a first valve 6a arranged around the radio frequency coil 41. The first valves 6a are uniformly arranged circumferentially along the radio frequency coil 41, and the number can be set to 8, 12 or more depending on the process requirements. This arrangement facilitates the uniform distribution of multiple first valves 6a circumferentially, which is beneficial for achieving uniform gas supply and distribution within the process chamber 1 and improving the uniformity of process processing. Each first valve 6a is equipped with an independent optical fiber unit 62, and all optical fiber cables 64 are routed along the inner wall of the radio frequency chamber 2 and led out to the outside through a unified sealed connector panel.

[0031] like Figure 3 As shown, in another embodiment, the valve assembly includes a second valve 6b located inside the RF coil 41. The second valve 6b is positioned in the central region of the RF coil 41, with its outlet directly connected to the inlet at the center of the process cavity. This arrangement allows for central gas supply while further shortening the gas path length and improving the response speed of gas supply switching. The central gas supply scheme is particularly suitable for process scenarios requiring uniform gas supply to the central region of the substrate W, and can also be used in conjunction with the surrounding first valve 6a to achieve center-edge coordinated gas supply.

[0032] like Figure 4 As shown, in another embodiment, the RF component 4 includes an upper electrode 9, which hermetically isolates the process cavity 1 and the RF cavity 2. The upper electrode 9 is made of a conductive metal material and serves as one plate of a capacitor, forming a capacitive coupling with the base 3. The alternating electric field generated by the upper electrode 9 ionizes the process gas in the process cavity 1, generating capacitively coupled plasma. The alternating electric field generated when the upper electrode is working can also cause serious interference to electromagnetic sensors, while the fiber optic detection scheme is immune to electric field interference.

[0033] like Figure 2As shown, in one embodiment, the valve body 61 includes a pneumatic diaphragm valve. The pneumatic diaphragm valve has a diaphragm inside, and the valve stem, driven by an actuator, moves the diaphragm to open and close the gas passage. The actuator is a pneumatic actuator. Pneumatic diaphragm valves have advantages such as no stuffing box, good sealing performance, low flow resistance, and corrosion resistance, making them particularly suitable for the high vacuum and highly corrosive process gas environments in semiconductor manufacturing. They also have excellent response speed, achieving millisecond-level opening and closing. The pneumatic diaphragm valve can use any known technology, such as commercially available ALD valves, which will not be elaborated upon here.

[0034] For example, the diaphragm can be made of nickel-cobalt alloy, which has excellent fatigue resistance and corrosion resistance. The valve seat is made of PFA material, which has excellent chemical inertness and sealing performance. The valve body is made of SUS316L stainless steel, and the surfaces in contact with the gas are electropolished to a surface roughness Ra of less than 0.3 μm, minimizing particle generation and gas adsorption.

[0035] In one embodiment, the fiber optic unit 62 employs a through-beam detection structure, including a transmitter and a receiver. The transmitter and receiver are respectively located on opposite sides of the valve stem's movement path, and a light-shielding plate is provided on the valve stem. When the valve stem moves to the closed position, the light-shielding plate is positioned between the transmitter and receiver, blocking the optical path, and the receiver does not receive an optical signal; the fiber optic amplifier outputs a valve-closed status signal. When the valve stem moves to the open position, the light-shielding plate moves away from the optical path, the receiver receives the optical signal, and the fiber optic amplifier outputs a valve-open status signal. This through-beam detection scheme has a simple and reliable structure, high detection accuracy, and strong anti-interference capability.

[0036] In another embodiment, the fiber optic unit 62 employs a reflective detection structure. The end of the fiber optic unit 62 is positioned facing a reflective surface on the valve stem. This reflective surface can be directly machined onto the end face of the valve stem or it can be a reflective sheet mounted on the valve stem. When the valve stem moves to different positions, the distance between the reflective surface and the end of the fiber optic unit changes, causing a change in the intensity of the reflected light. The fiber optic amplifier determines the valve's open / closed state by detecting the change in the intensity of the reflected light. This reflective approach requires only a single fiber for detection, resulting in less installation space and making it particularly suitable for space-constrained applications.

[0037] Of course, the fiber optic unit and fiber optic amplifier can be any existing solution, such as commercially available fiber optic probe products, which will not be elaborated here.

[0038] For example, the fiber optic cable 64 can be made of high-temperature resistant special optical fiber. The fiber optic cable 64 is covered with a stainless steel braided protective layer, which has good mechanical strength and wear resistance. The sealing connector 65 adopts a vacuum sealing structure, including a compression nut, a sealing washer, and an optical fiber pass-through component, which ensures that the fiber optic cable can pass smoothly through the cavity wall while maintaining the high vacuum environment of the radio frequency cavity.

[0039] In one embodiment, the fiber optic amplifier 63 can be installed inside the electrical control cabinet of the equipment, outside the range of radio frequency interference. The fiber optic amplifier 63 internally includes a laser diode driving circuit, a photodiode receiving circuit, a signal amplification and filtering circuit, a threshold comparison circuit, and an output interface circuit. All electronic circuits operate in a clean, interference-free environment, ensuring high signal processing accuracy. The fiber optic amplifier 63 supports both NPN and PNP output modes and can directly drive relays or be connected to a PLC control system. The fiber optic amplifier 63 is also equipped with a digital display window that can display the currently received light intensity value and threshold setting value in real time, facilitating installation, debugging, and fault diagnosis. The fiber optic amplifier 63 can have automatic calibration and automatic threshold tracking functions, compensating for changes in fiber loss over long-term use and ensuring detection reliability.

[0040] like Figure 1 As shown, in one embodiment, the fiber optic unit 62 is located within the axial range of the RF component 4 along the axial direction of the RF cavity 2. This arrangement fully utilizes the free space above and below the RF component 4 to arrange the valve component 6, minimizing the overall space occupied by the device. However, in this compact layout, the fiber optic unit 62 is located in the region with the strongest RF electromagnetic field and is close to the RF coil 41, resulting in the most severe electromagnetic interference. Traditional electromagnetic sensors cannot function properly in this environment, exhibiting a high false alarm rate and even permanent damage. In contrast, the fiber optic detection solution, due to its inherent anti-electromagnetic interference characteristics, can maintain extremely high detection accuracy in this environment without any shielding measures.

[0041] like Figure 1 As shown, in one embodiment, the process chamber 1 is provided with an air intake ring 10, which surrounds the side wall of the process chamber 1. The air intake ring 10 has multiple air inlets 11 for supplying air to the process chamber 1. The valve assembly includes multiple air intake valves, which are installed on the air intake ring 10 and correspond one-to-one with the air inlets 11. The outlet of each air intake valve is directly connected to the corresponding air inlet 11, minimizing air intake delay, greatly shortening the gas path length, and enabling rapid air supply switching. Simultaneously, this structure allows for uniform gas distribution within the process chamber 1, improving the uniformity of the process. Since each air inlet 11 corresponds to an independent air intake valve, independent control of the air intake volume in different areas can be achieved, further improving the flexibility and accuracy of the process. Each air intake valve is equipped with an independent fiber optic unit 62, and all fiber optic cables 64 converge to a fiber optic amplifier array outside the radio frequency cavity 2, enabling centralized detection and management of the status of multiple valves.

[0042] The sensor can be installed at any angle around the valve without fixed positions, eliminating the need for positioning slots or pins. This design significantly reduces manufacturing and assembly complexity, while also providing greater flexibility in the overall equipment layout, allowing for adjustments to the fiber optic cable routing based on available space. After installation, sensor calibration is required, adjusting the fiber optic amplifier's detection threshold to ensure accurate and reliable detection.

[0043] This utility model is not limited to the specific embodiments described above. Any modifications made by those skilled in the art based on the above concept without creative effort shall fall within the protection scope of this utility model.

Claims

1. A plasma processing device, characterized in that, The system includes a process cavity and a radio frequency (RF) cavity. The process cavity contains a base to support a substrate, and the RF cavity contains an RF component electrically connected to an RF source. The RF source feeds RF energy into the process cavity through the RF component to excite plasma within the process cavity to process the substrate. The radio frequency cavity is equipped with a valve assembly. The outlet of the valve assembly is connected to the inlet of the process cavity. The valve assembly includes a valve body and a fiber optic position detection unit. The fiber optic position detection unit includes a fiber optic unit and a fiber optic amplifier. The fiber optic unit is located on the valve body and is used to detect the opening and closing state of the valve. The fiber optic amplifier is located outside the radio frequency cavity.

2. The plasma processing equipment as described in claim 1, characterized in that, The radio frequency component includes a radio frequency coil, and the process cavity and the radio frequency cavity are hermetically separated by a dielectric window.

3. The plasma processing equipment as described in claim 2, characterized in that, The valve assembly includes a first valve disposed around the radio frequency coil.

4. The plasma processing equipment as described in claim 2, characterized in that, The valve assembly includes a second valve located inside the radio frequency coil.

5. The plasma processing apparatus as described in claim 1, characterized in that, The radio frequency component includes an upper electrode, and the process cavity and the radio frequency cavity are hermetically separated by the upper electrode.

6. The plasma processing apparatus as described in claim 1, characterized in that, The valve body includes a pneumatic diaphragm valve, which includes a valve stem and a diaphragm. The valve stem drives the diaphragm to move under the drive of the actuator to open and close the valve.

7. The plasma processing apparatus as described in claim 6, characterized in that, The optical fiber unit includes a transmitter and a receiver, which are respectively located on both sides of the valve stem's movement path. The valve stem is equipped with a light-shielding plate. When the valve stem moves to different positions, the light-shielding plate blocks or opens the optical path to detect the valve's open / closed state.

8. The plasma processing apparatus as described in claim 6, characterized in that, The optical fiber unit adopts a reflective detection structure, with the end of the optical fiber unit facing the reflective surface on the valve stem. The valve opening / closing status is detected by detecting changes in the intensity of the reflected light.

9. The plasma processing apparatus as described in claim 1, characterized in that, The optical fiber unit is connected to the optical fiber amplifier via an optical fiber cable, which passes through a sealed connector on the RF cavity housing and extends to the outside of the RF cavity.

10. The plasma processing apparatus as described in claim 1, characterized in that, The process chamber is provided with an air intake ring, which surrounds the side wall of the process chamber and has multiple air inlets. The valve assembly includes multiple air intake valves, which are installed on the air intake ring and are configured to correspond one-to-one with the air inlets.

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