A lower electrode assembly and ion beam etching machine

Abstract

The application discloses a lower electrode assembly and an ion beam etching machine, and the lower electrode assembly comprises a plurality of pressing rings (1), an electrode plate (2) and a fixing ring (5). The plurality of pressing rings (1) are arranged above the electrode plate (2) in a circumferential interval, each pressing ring (1) is arranged on the fixing ring (5) through a rotatable push rod (3) arranged correspondingly, and an end of the pressing ring (1) forms a pressing part matched with a wafer to be processed. The pressing ring (1) can be driven to rotate by the rotatable push rod (3) so as to adjust the radial distance of the pressing part relative to the center of rotation of the lower electrode. By the application, the phenomenon that a manipulator collides with the pressing ring during transmission can be prevented; the contact area with the wafer is reduced by using the pressing edge at the vertex of each pressing ring, the yield of wafer etching can be effectively improved; meanwhile, the pressing adaptation of wafers of different sizes can be adapted, the application has good adaptability, the operation time can be effectively reduced on the basis of reducing the cost.

Description

Technical Field

[0001] This invention relates to the field of semiconductor processing equipment technology, specifically to a lower electrode assembly and ion beam etching machine for use with multi-size wafers. Background Technology

[0002] Etching is a crucial process in semiconductor processing, microelectronics manufacturing, and LED production. As the integration density of semiconductor devices increases, the requirements for dimensional control during production also become more stringent, leading to ever-higher demands for etching precision. Common etching methods include dry etching and wet etching. Compared to wet etching, dry etching offers advantages such as better anisotropy, higher selectivity, process controllability, better repeatability, and no chemical waste pollution. Dry etching can be further categorized into photoelectrolysis etching, vapor phase etching, plasma etching, and ion beam etching.

[0003] Ion beam etching utilizes the principle of glow discharge to decompose argon gas into argon ions. These argon ions are accelerated by an anolyte electric field and physically bombard the sample surface to achieve etching. It can be widely used to etch various metals and their alloys, as well as non-metals, oxides, nitrides, carbides, semiconductors, polymers, ceramics, infrared materials, and superconductors. The lower electrode structure is the core structure of ion beam etching, serving to support, cool, and rotate the wafer. The design of the lower electrode assembly plays a crucial role in ion beam etching and directly affects wafer yield.

[0004] Current technologies for fixing wafers on the lower electrode stage mainly include two methods: mechanical clamping rings and electrostatic chucks. Compared to mechanical clamping rings, electrostatic chucks can effectively improve yield, significantly reduce breakage rate, and improve etching uniformity, but their cost is higher, and subsequent maintenance costs are also higher. Therefore, mechanical clamping rings are still widely used. When processing wafers of different sizes, it is necessary to purchase additional equipment or change the lower electrode to adapt to the corresponding wafer size.

[0005] In view of this, there is an urgent need to optimize the structure of the lower electrode assembly of existing ion beam etching machines to make it suitable for wafer processing of different sizes. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a multi-size compatible lower electrode assembly and an ion beam etching machine. Through improvements and optimizations to the lower electrode assembly, it can be applied to the processing of wafers of different sizes and effectively improve operational efficiency.

[0007] The present invention provides a lower electrode assembly for an ion beam etching machine, comprising multiple pressure rings, an electrode plate, and a fixing ring; the multiple pressure rings are circumferentially spaced above the electrode plate, each pressure ring is mounted on the fixing ring by a corresponding rotatable push rod, and the end of the pressure ring forms a pressing portion adapted to the wafer to be processed; the pressure ring can be rotated by the rotatable push rod to adjust the radial distance of its pressing portion relative to the rotation center of the lower electrode.

[0008] Optionally, the rotatable push rod passes through the electrode plate and is connected to the fixed ring.

[0009] Optionally, the rotatable push rod includes a rotating shaft and a fixed shaft nested inside and outside. The fixed shaft is cylindrical and its bottom is fixedly connected to the fixed ring. The pressure ring is fixed to the upper end of the rotating shaft and drives the pressure ring to rotate through the rotating shaft.

[0010] Optionally, it also includes a drive component that drives the rotating shaft to rotate via a transmission mechanism.

[0011] Optionally, the drive component includes a plurality of servo motors corresponding to the plurality of pressure rings, and the output end of each servo motor is connected to the corresponding rotating shaft via a belt.

[0012] Optionally, the rotating shaft is provided with a gear structure, and the cylindrical wall of the fixed shaft is provided with an opening so that the belt can be adapted to the gear structure on the rotating shaft through the opening.

[0013] Optionally, the rotatable push rod further includes a bushing and a bearing, the bushing being nested between the rotating shaft and the fixed shaft; the bearing being fixedly disposed at the bottom of the fixed shaft and located between the rotating shaft and the fixed shaft.

[0014] Optionally, it also includes a plurality of circumferentially spaced ejector pin mechanisms, each ejector pin mechanism including a first ejector pin and a second ejector pin, wherein the second ejector pin is positioned relative to the first ejector pin and close to the rotation center of the stage; both the second ejector pin and the first ejector pin extend through the through hole of the electrode plate and can move up and down under the drive of the fixing ring.

[0015] Optionally, the first ejector pin and the second ejector pin are connected by a transition plate, wherein the second ejector pin is fixed on the transition plate by a second ejector pin pressure plate, and the first ejector pin is fixed on the fixing ring by a first ejector pin pressure plate.

[0016] The present invention also provides an ion beam etching machine, including a lower electrode assembly, wherein the lower electrode assembly is the lower electrode assembly as described above.

[0017] In response to existing technologies, this invention proposes a structural optimization design for the adaptability of the lower electrode assembly. Specifically, it includes multiple independently adjustable pressure rings, which are circumferentially spaced above the electrode plate. Each pressure ring is mounted on a fixed ring via a corresponding rotatable push rod, and the end of the pressure ring forms a pressing part adapted to the wafer to be processed. It can be rotated by the corresponding rotatable push rod to adjust the radial distance of its pressing part relative to the rotation center of the lower electrode. Compared to the circular clamping ring used in transmission, this solution divides the clamping ring's functional structure into multiple circumferentially spaced parts, preventing the robotic arm from impacting the clamping ring during transport. By utilizing the clamping edge at the apex of each clamping ring, the solution effectively addresses the low utilization rate of traditional clamping rings with excessive clamping edges, reducing the contact area between the clamping ring and the wafer and thus significantly improving wafer etching yield. Simultaneously, each clamping ring rotates relative to the electrode plate, allowing its apex to adapt to clamping different sized wafers. This eliminates the need for opening cavities to replace the lower electrode or purchasing additional machines of different sizes, providing excellent adaptability and greatly reducing costs and related operation time.

[0018] In an optional embodiment of the present invention, the rotatable push rod includes a rotating shaft and a fixed shaft nested together. The fixed shaft is cylindrical and its bottom is fixedly connected to a fixed ring. A pressure ring is fixed to the upper end of the rotating shaft and drives its rotation via the rotating shaft. Furthermore, the driving component includes multiple servo motors corresponding to the multiple pressure rings. The output end of each servo motor is connected to the corresponding rotating shaft via a belt. The structure is simple and reliable, and has good operability.

[0019] In another optional embodiment of the present invention, the ejector mechanism includes a first ejector and a second ejector, with the second ejector positioned relative to the first ejector and close to the center of rotation of the wafer stage. That is, the second ejector is suitable for small-sized wafers, and the first ejector is suitable for large-sized wafers. In practical applications, for small-sized wafers, the second ejector provides reliable support, meeting the corresponding process requirements; simultaneously, for large-sized wafers exhibiting a tendency to slide, the second ejector provides simultaneous support, preventing wafer slippage or even falling from affecting the process results. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the lower electrode assembly described in the specific embodiment;

[0021] Figure 2 for Figure 1 A cross-sectional view of the rotatable push rod shown;

[0022] Figure 3 for Figure 1 A schematic diagram of the rotary joint shown in the figure;

[0023] Figure 4 for Figure 1 A cross-sectional view of the magnetohydrodynamic shaft shown;

[0024] Figure 5 for Figure 1 A schematic diagram of the structure of the vacuum electrode shown;

[0025] Figure 6 for Figure 1 A schematic diagram of the ejector mechanism shown in the figure;

[0026] Figure 7 Based on Figure 1 The diagram shows the workflow of the lower electrode assembly.

[0027] In the picture:

[0028] 1. Pressure ring, 2. Electrode plate, 3. Rotatable push rod, 301. Rotating shaft, 302. Fixed shaft, 303. Bushing, 304. Bearing, 305. Opening, 306. Gear structure, 4. Ejector pin, 401. First ejector pin, 402. Transition plate, 403. Second ejector pin pressure plate, 404. First ejector pin pressure plate, 405. Fixed ring, 5. Belt, 6. Servo motor, 7. Cylinder, 8. Magnetofluid shaft, 9. Circular hole, 901. Through hole, 902. Large swing piece, 10. Motor, 11. Rotary joint, 12. Stepped hole, 1201. Vacuum electrode, 13. Ceramic body, 1301. Wire connector, 1302. Wire connector, 1303. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] The lower electrode assembly is the core structure of ion beam etching, used to support, cool, and rotate the wafer. Before etching, the wafer needs to be reliably fixed on the wafer stage of the lower electrode. A typical method is to use a mechanical clamping ring. However, due to the limitations of the existing mechanical clamping ring structure, it cannot be used for processing wafers of different sizes. It is necessary to purchase different specifications of equipment or replace the lower electrode to process wafers of corresponding sizes.

[0031] Based on this, embodiments of this application provide a lower electrode assembly shared by multiple wafer sizes, which uses a mechanical clamping ring to clamp the wafer. Dividing the traditional circular clamping ring into multiple circumferentially spaced parts prevents the robotic arm from impacting the clamping ring during transport. Utilizing the edge clamping at the apex of each clamping ring effectively solves the problem of low utilization rate due to excessive edge clamping in traditional clamping rings. Simultaneously, each clamping ring rotates relative to the electrode plate so that its apex can adapt to clamping different sized wafers.

[0032] Without loss of generality, this embodiment is based on the lower electrode assembly shared by multiple wafer sizes shown in the figure, which has three pressure rings that can rotate relative to the electrode plate, and a pressing portion is formed at the apex of each pressure ring to press the wafer to be processed. Please refer to... Figure 1 The figure is a schematic diagram of the overall structure of the lower electrode assembly shared by multiple wafer sizes as described in this embodiment.

[0033] like Figure 1 As shown, the lower electrode assembly mainly includes a pressure ring 1, an electrode plate 2, a rotatable push rod 3, a ejector pin 4, a fixing ring 5, a belt 6, a servo motor 7, a cylinder 8, a magnetohydrodynamic shaft 9, a large swing component 10, a motor 11, and a rotary joint 12.

[0034] In actual operation, the upper part of the large ornament 10 is the vacuum side, and the lower part is the atmospheric side. After the entire assembly is completed, both the upper and lower surfaces of the large ornament 10 can be sealed using sealing rings or other sealing methods, thus isolating the vacuum side from the atmospheric side. It is understandable that different methods can be used in specific implementations based on the sealing relationship established by the large ornament 10, which will not be elaborated upon in this paper.

[0035] Each pressure ring 1 is equipped with a servo motor 7 that provides rotational driving force. For the actual size of the wafer to be processed, the rotation angle of the servo motor 7 can be controlled to drive the internal shaft of the rotatable push rod 3 to rotate, further driving the pressure ring 1 to rotate, thereby adjusting the end vertex of the pressure ring 1 into position. It can be understood that as the rotation angle of the pressure ring 1 changes, the radial distance from its end vertex to the rotation center of the lower electrode stage can be adjusted to accommodate wafers of different sizes. After adjustment, the wafer processing workflow begins.

[0036] The pressure ring 1 shown in the figure is arc-shaped to minimize the impact on the wafer surface to be processed. Of course, in other specific implementations, the pressure ring 1 can be a straight section or other structural forms.

[0037] In addition, the material of the pressure ring 1 can be selected according to actual needs, and should have characteristics such as high temperature resistance, light weight, and resistance to ion beam bombardment, such as, but not limited to, using aluminum alloy pressure ring.

[0038] It should be noted that in this embodiment, each pressure ring 1 is independently driven by a corresponding servo motor 7. Of course, in other specific applications, each pressure ring 1 can also be driven by a servo motor as a driving component (not shown in the figure), and at the same time, the driving force is transmitted to the rotatable push rod 3 of each pressure ring 1 in conjunction with the planetary gear transmission mechanism.

[0039] The rotatable push rod 3 includes a rotating shaft 301 and a fixed shaft 302 nested together. A bushing 303 is provided between the rotating shaft 301 and the fixed shaft 302. The rotating shaft 301 is connected to the belt 6 for transmission and rotates relative to the fixed shaft 302 under the drive of the servo motor 7. Please refer to [further details omitted]. Figure 1 and Figure 2 ,in, Figure 2 for Figure 1 The cross-sectional view of the rotatable push rod shown.

[0040] The rotatable push rod 3 passes entirely through the electrode plate 2, and its fixed shaft 302 is fixed at its bottom to the fixed ring 5 below the electrode plate 2. The pressure ring 1 is fixed to the upper end of the rotating shaft 301 to support the pressure ring 1 and drive its rotation. Figure 1 As shown, the fixing ring 5 is located below the electrode plate 2, and can drive the rotatable push rod 3 and the pressure ring 1 to move up and down under the action of the cylinder 8, so as to realize the pressing or loosening operation of the wafer to be processed.

[0041] Of course, in other specific applications, the rotatable push rod 3 can also be located beside the electrode plate 2, rather than being limited to the assembly method shown in the figure that passes through the electrode plate 2.

[0042] like Figure 2 As shown, a gear structure 306 is provided on the rotating shaft 301, which is used for transmission connection with the belt 6; the fixed shaft 302 is cylindrical, and correspondingly, an opening 305 is provided on its side wall at a position radially opposite to the gear structure 306, so that the belt 6 can be adapted to the gear structure 306 on the rotating shaft 301 through the opening 305. A gear structure adapted to the belt 6 can also be provided on the output end of the servo motor 7 (not shown in the figure), thereby establishing belt transmission.

[0043] In other specific implementations, the gear structure on the rotating shaft 301 can also be located at its shaft end, that is, the rotating shaft 301 extends out of the bottom end of the fixed shaft 302. In this way, there is no need to open an opening on the fixed shaft 302 for the belt to pass through. In addition, the parts of the rotating shaft 301 and the output end of the servo motor 7 that establish the above-mentioned transmission connection with the belt 6 are not limited to being set as gear structures. Specifically, they can be in the form of a shaft or a pulley. In other words, as long as the rotational driving force output by the servo motor 7 can be transmitted to the rotating shaft 301 via the belt 6, it is within the scope of protection claimed in this application.

[0044] In this embodiment, bearings 304 are also provided at the bottom of the rotating shaft 301 and the fixed shaft 302 to establish a good rotational relationship between the rotating shaft 301 and the fixed shaft 302, and the wear between the two can be reduced and lubricated by the bushing 303 spaced between the rotating shaft 301 and the fixed shaft 302.

[0045] Here, the bearing 304 can be fixed to the bottom of the fixed shaft 302 by welding or interference fit, and the rotating shaft 301 is connected to the bearing 304 to achieve axial positioning between the rotating shaft 301 and the fixed shaft 302.

[0046] In this embodiment, the rotary joint 12 is located on the atmospheric side, and cooling water and back heat are introduced from outside the conduit into the electrode plate 2 through the rotary joint 12. It is understood that the aforementioned functional structure for cooling the wafer during the etching process can be implemented based on existing technology, and therefore will not be elaborated further here. Please refer to [link to relevant documentation] for details. Figure 3 The figure shows a schematic diagram of the rotary joint.

[0047] like Figure 3 As shown, the rotary joint 12 has a stepped hole 1201 at the opposite end to the magnetofluid shaft 9. This hole is used to house the vacuum electrode 13 connected to the magnetofluid shaft 9, and allows the vacuum electrode 13 to be pressed tightly by the stepped surface of the stepped hole 1201 when fixed to the magnetofluid shaft, thus achieving a sealing effect. Please refer to [further details omitted]. Figure 4 The image is Figure 1 The cross-sectional view of the magnetohydrodynamic shaft shown.

[0048] As shown in Figure 4, a circular hole 901 is provided at the opposite end of the magnetofluid shaft 9 and the rotary joint 12. The circular hole 901 is used to place the vacuum electrode 13 connected to the rotary joint 12. That is, a part of the structure of the vacuum electrode 13 is placed in the stepped hole 1201 of the rotary joint 12, and another part of the structure is placed in the circular hole 901 of the magnetofluid shaft 9. At the same time, the magnetofluid shaft 9 also has two through holes 902 that communicate with the circular hole 901. The two through holes 902 are formed by extending axially from the circular hole 901 and then radially, respectively, to guide the wires connected to the vacuum electrode 13 and guide the wires to the outside of the magnetofluid shaft 9, that is, the vacuum side, thereby realizing the functional requirement of introducing the wires from the atmospheric side to the vacuum side.

[0049] Please see also Figure 5 The figure shows Figure 1 The diagram shows the structure of the vacuum electrode 13.

[0050] like Figure 5 As shown, the vacuum electrode 13 includes an insulated ceramic body 1301. Two wire connectors 1302 and 1303 for each electrode are located on opposite sides of the ceramic body 1301. Wire connector 1302 connects to one side of the magnetofluidic shaft 9, and wire connector 1303 connects to the other side of the rotary joint, enabling the transmission of wires from the atmospheric side to the rotating electrode in the vacuum. The vacuum electrode 13 is mounted between the magnetofluidic shaft 9 and the rotary joint 12. The rotary joint 12 tightly presses the vacuum electrode 13 onto the magnetofluidic shaft 9, and a sealing ring provides a seal.

[0051] In other specific implementations, the vacuum electrode 13 can also be directly welded to the magnetofluid shaft 9, which can greatly reduce the risk of leakage. Using the above connection method, fixing the vacuum electrode 13 between the magnetofluid shaft 9 and the rotary joint 12 can keep the wires in the magnetofluid shaft 9 in a vacuum, and the area is statically sealed, which greatly reduces the probability of excessive leakage at this point.

[0052] Meanwhile, the relevant cables of the servo motor 7 can be connected to the wire connector 1301 or the wire connector 1302. In this way, when the motor 11 controls the electrode plate 2 to rotate through the magnetofluid shaft 9, the cable, servo motor 7, vacuum electrode 13, magnetofluid shaft 9, and rotary joint 12 rotate synchronously, thereby avoiding the cable from getting tangled due to relative movement between the cable and the cable connection parts.

[0053] Furthermore, to improve the reliability of the robotic arm's wafer placement operation, the ejector mechanism 4 in this embodiment includes a first ejector 401 and a second ejector 402, which are also described in detail below. Figure 6 The figure shows Figure 1 The diagram shows the structure of the ejector pin mechanism.

[0054] like Figure 6 As shown, the first ejector pin 401 and the second ejector pin 402 are integral structures, and the two are connected by a transition plate 403. The second ejector pin 402 is fixed on the transition plate 403 by the second ejector pin pressure plate 404. The entire ejector pin mechanism is fixed on the fixing ring 5 by the first ejector pin pressure plate 405 on the first ejector pin 401.

[0055] Both the first ejector pin 401 and the second ejector pin 402 can extend through vias in the electrode plate 2 to abut against the bottom surface of the wafer to be processed. Figure 1 As shown, relative to the first ejector pin 401, the second ejector pin 402 is located on the side close to the center of rotation of the stage. In other words, the second ejector pin 402 is suitable for small-sized wafers, such as, but not limited to, 200mm wafers, while the first ejector pin 401 is suitable for large-sized wafers, such as, but not limited to, 150mm and 100mm wafers.

[0056] Here, for small-sized wafers, the second ejector pin 402 can provide reliable support to meet the corresponding process requirements; at the same time, when large-sized wafers tend to slide, the second ejector pin 402 can provide support simultaneously to prevent the wafer from sliding or even falling off, which would affect the process results.

[0057] In specific implementation, the number of ejector mechanisms 4 can be determined according to the overall design requirements of the equipment. For example, but not limited to, at least three ejector mechanisms 4 are configured with circumferential intervals to meet the functional requirements of circumferential uniform load bearing.

[0058] Of course, in other specific implementations, the first ejector pin 401 and the second ejector pin 402 can also adopt a separate structure and be independently set on the fixing ring 5, which can also be adapted to wafers of different sizes to be processed.

[0059] The following is combined Figure 7 Briefly describe the working process of the lower electrode assembly described in this embodiment.

[0060] like Figure 7 As shown, perform the following preparatory steps before starting:

[0061] S01, Select the corresponding wafer size. This can be done through the operation interface. Enter the size of the wafer to be processed.

[0062] S02, by controlling the rotation angle of the servo motor 7, the belt drives the rotating shaft 301 inside the push rod 3 to rotate, adjusting the pressure ring 1 to a position that matches the size of the wafer, so that its apex can adapt to the clamping fit of wafers of different sizes.

[0063] Then, the formal workflow begins. The specific process steps are as follows:

[0064] S1, the robotic arm carries the wafer into the process chamber; in this embodiment, the traditional circular pressure ring is divided into multiple circumferentially spaced parts to prevent the robotic arm from impacting the pressure ring during the transfer process.

[0065] S2, the robotic arm descends and places the wafer on the ejector pin 4; here, the precise alignment between the wafer to be processed and the center of the lower electrode stage can be finely adjusted and compensated by program control, without the need for cavity adjustment, which can effectively improve work efficiency.

[0066] S3, the robotic arm retracts into the transmission chamber;

[0067] S4, under the action of cylinder 8, the fixed ring 5 descends relative to the electrode plate 2;

[0068] S5, the ejector pin 4 and the pressure ring 1 descend under the drive of the fixing ring 5, pressing the wafer to be processed; in this embodiment, the edge pressing at the apex of each pressure ring is used to effectively solve the disadvantage of low effective utilization rate caused by excessive edge pressing of traditional pressure rings.

[0069] S6, begin processing;

[0070] S7. After the process is completed, the fixed ring 5 rises under the action of the cylinder 8.

[0071] S8, the ejector pin 5 and the pressure ring 1 rise under the action of the fixing ring 5, lifting the wafer;

[0072] S9, the robotic arm enters the process chamber;

[0073] S10, the robotic arm rises and removes the wafer;

[0074] S11, the robotic arm retracts into the transmission chamber;

[0075] S12, remove the wafer that has completed the process and put in a new wafer to be processed.

[0076] When it is necessary to change to a wafer of a different size, the steps S01 and S02 for adjusting the wafer size need to be repeated. After adjusting the position of the pressure ring 1, the corresponding operation for the wafer to be processed can be performed. With this setup, the working position of the pressure ring 1 is adjusted by software control, eliminating the need to open the cavity to replace the lower electrode, which reduces equipment costs and significantly reduces operation time.

[0077] In addition to the aforementioned lower electrode assembly, this embodiment also provides an ion beam etching machine, which includes the aforementioned lower electrode assembly, to be suitable for processing wafers of different sizes. It should be understood that other functions of this ion beam etching machine are not the core inventive points of this application, and can be implemented by those skilled in the art based on existing technology; therefore, they will not be described further herein.

[0078] This solution allows for the clamping operation of wafers of different sizes. The working position of each clamping ring is adjusted and controlled via a program, eliminating the need for opening a cavity to replace the lower electrode or purchasing additional equipment of different sizes. It offers good adaptability, significantly reducing costs and operation time. Furthermore, this implementation scheme, by adapting the end apex of the clamping ring to the wafer surface, reduces the contact area between the clamping ring and the wafer, effectively improving wafer etching yield.

[0079] It should be noted that the above embodiments provided in this implementation have compatible rotary joints and magnetohydrodynamic shafts, and their specific functional implementation is not limited to the structural form shown in the figure. As long as the core concept is consistent with this solution, it is within the scope of protection claimed in this application.

[0080] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lower electrode assembly for use in an ion beam etching machine, characterized in that, It includes multiple pressure rings (1), electrode plates (2) and fixing rings (5); The plurality of pressure rings (1) are arranged circumferentially above the electrode plate (2). Each pressure ring (1) is mounted on the fixed ring (5) by a corresponding rotatable push rod (3), and the end of the pressure ring (1) forms a pressing part adapted to the wafer to be processed. The pressure ring (1) can be driven to rotate by the rotatable push rod (3) to adjust the radial distance of its pressing part relative to the rotation center of the lower electrode. It also includes multiple circumferentially spaced ejector pin mechanisms (4), each ejector pin mechanism (4) including a first ejector pin (401) and a second ejector pin (402), and the second ejector pin (402) is positioned close to the rotation center of the stage relative to the first ejector pin (401); both the second ejector pin (402) and the first ejector pin (401) extend through the through hole of the electrode plate (2) and can move up and down under the action of the fixing ring (5).

2. The lower electrode assembly according to claim 1, characterized in that, The rotatable push rod (3) passes through the electrode plate (2) and is connected to the fixed ring (5).

3. The lower electrode assembly according to claim 1 or 2, characterized in that, The rotatable push rod (3) includes a rotating shaft (301) and a fixed shaft (302) nested inside and outside. The fixed shaft (302) is cylindrical and its bottom is fixedly connected to the fixed ring (5). The pressure ring (1) is fixed at the upper end of the rotating shaft (301) and drives the pressure ring (1) to rotate through the rotating shaft (301).

4. The lower electrode assembly according to claim 3, characterized in that, It also includes a drive component that drives the rotating shaft (301) to rotate via a transmission mechanism.

5. The lower electrode assembly according to claim 4, characterized in that, The drive component includes a plurality of servo motors (7) corresponding to the plurality of pressure rings (1), and the output end of each servo motor (7) is connected to the corresponding rotating shaft (301) via a belt (6).

6. The lower electrode assembly according to claim 5, characterized in that, The rotating shaft (301) is provided with a gear structure (306), and the cylindrical wall of the fixed shaft (302) is provided with an opening (305) so that the belt (6) can be adapted to the gear structure (306) on the rotating shaft (301) through the opening (305).

7. The lower electrode assembly according to claim 3, characterized in that, The rotatable push rod (3) also includes a bushing (303) and a bearing (304). The bushing (303) is nested between the rotating shaft (301) and the fixed shaft (302). The bearing (304) is fixedly disposed at the bottom of the fixed shaft (302) and is located between the rotating shaft (301) and the fixed shaft (302).

8. The lower electrode assembly according to claim 1, characterized in that, The first ejector pin (401) and the second ejector pin (402) are connected by a transition plate (403). The second ejector pin (402) is fixed on the transition plate (403) by a second ejector pin pressure plate (404), and the first ejector pin (401) is fixed on the fixing ring (5) by a first ejector pin pressure plate (405).

9. An ion beam etching machine, comprising a lower electrode assembly, characterized in that, The lower electrode assembly is the lower electrode assembly according to any one of claims 1 to 8.

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