A lower electrode assembly, a method of installing the same, and a plasma processing apparatus

Abstract

The application provides a lower electrode assembly for carrying a substrate to be processed, comprising a carrying base and a peripheral ring assembly surrounding the carrying base, wherein the peripheral ring assembly comprises a focusing ring surrounding the substrate and the carrying base, an insertion ring below the focusing ring and surrounding the carrying base, and a first elastic ring between the peripheral ring assembly and the carrying base, wherein the first elastic ring is provided with protrusions on the side close to the carrying base and / or the side close to the peripheral ring assembly. The elastic ring structure can ensure the safe use of the lower electrode assembly in a large working temperature range. Compared with the prior art, the technical scheme of the application improves the consistency and simplicity of the plasma processing equipment.

Description

Technical Field

[0001] This invention relates to the field of plasma etching technology, and more particularly to a plasma processing technology applicable to a wide operating temperature range under high radio frequency power. Background Technology

[0002] Microfabrication of semiconductor substrates is a well-known technique used to manufacture, for example, semiconductors, flat panel displays, light-emitting diodes (LEDs), and solar cells. A crucial step in microfabrication is the plasma processing step, which takes place inside a reaction chamber where process gases are introduced. An radio frequency (RF) source, coupled to the reaction chamber via inductance and / or capacitance, excites the process gases to form and maintain plasma. Inside the reaction chamber, the exposed substrate is supported by a lower electrode assembly and held in a fixed position by a clamping force to ensure substrate safety and a high yield rate during the process.

[0003] The lower electrode assembly includes not only an electrostatic chuck for fixing the substrate and a base for supporting the electrostatic chuck, but also an edge ring assembly surrounding the base. During the substrate manufacturing process, the lower electrode assembly is used not only to support and fix the substrate, but also to control the temperature, electric field distribution, etc. of the substrate.

[0004] In the prior art, aluminum is commonly used as the material for the base, while the material of the insertion ring surrounding the base is usually ceramic. Since the thermal expansion coefficients of the two are quite different, in order to ensure that the base can work in a wide temperature range, a certain gap must be set between the insertion ring and the base to accommodate the thermal expansion and contraction of the base.

[0005] As substrate processing precision increases, the radio frequency (RF) power applied to the reaction cavity also increases. High RF power can easily cause discharges within the confined space of the reaction cavity, damaging the substrate and its peripheral components, and seriously threatening the stability and safety of the lower electrode assembly. Therefore, a solution is urgently needed to adapt to plasma processing with a wide operating temperature range under the ever-increasing RF power environment. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention provides a lower electrode assembly for supporting a substrate to be processed, comprising a support base and an edge ring assembly surrounding the support base. The edge ring assembly includes: a focusing ring surrounding the substrate and the support base; and an insertion ring located below the focusing ring and surrounding the support base. A first elastic ring is disposed between the edge ring assembly and the support base, and the first elastic ring has a plurality of protrusions on one side facing the support base and / or one side facing the edge ring assembly.

[0007] Optionally, a second elastic ring is provided around the periphery of the first elastic ring, and the second elastic ring has a plurality of protrusions on the side of the first elastic ring and / or the side of the edge ring assembly.

[0008] Optionally, the first elastic ring has a plurality of first protrusions on the side near the edge ring assembly, and the second elastic ring has a plurality of second protrusions on the side near the first elastic ring, wherein the first protrusions and the second protrusions are located in horizontal planes at different heights.

[0009] Optionally, the first elastic ring may have several third protrusions on the side near the bearing base.

[0010] Optionally, the first protrusion and the third protrusion are located in horizontal planes at different heights.

[0011] Optionally, at least one of the first protrusion, the second protrusion, and the third protrusion is a continuous annular structure.

[0012] Optionally, at least one of the first protrusion, the second protrusion, and the third protrusion is a discontinuous strip structure.

[0013] Optionally, the lateral protrusion width of the first protrusion, the second protrusion, and the third protrusion is between 0.1mm and 0.5mm.

[0014] Optionally, the longitudinal protrusion height of the first protrusion, the second protrusion, and the third protrusion is between 0.1 mm and 1 mm.

[0015] Optionally, the number of protrusions on each side of the first elastic ring and the second elastic ring is less than or equal to 5.

[0016] Optionally, the edge ring assembly has a recessed portion on the inner side near the bearing base, and the second elastic ring is at least partially located within the recessed portion.

[0017] Optionally, the edge ring assembly has a recessed portion on the inner side near the bearing base, and the first elastic ring is at least partially located within the recessed portion.

[0018] Optionally, the second elastic ring does not have a protrusion on the side near the edge ring assembly.

[0019] Optionally, the first elastic ring and the second elastic ring are at least one of hard rubber, epoxy resin or Teflon.

[0020] Optionally, the protrusions divide the gap between the support base and the edge ring assembly into multiple sub-gap gaps, which may decrease as the temperature of the support base increases.

[0021] Furthermore, the present invention also discloses a plasma processing device, including a vacuum reaction chamber, characterized in that: a lower electrode assembly is disposed within the vacuum reaction chamber, and the lower electrode assembly includes the features described above.

[0022] Optionally, the support base includes a metal base and an electrostatic chuck located above the metal base.

[0023] Optionally, the operating temperature range of the vacuum reaction chamber is -60 degrees Celsius to 200 degrees Celsius.

[0024] Optionally, when the operating temperature range of the vacuum reaction chamber is lower than room temperature, several protrusions of the first elastic ring are tightly attached to the outer wall of the support base or to the inner wall of the edge ring assembly, so as to divide the gap between the edge ring assembly and the support base into two mutually isolated sub-gap.

[0025] Optionally, the vacuum reaction chamber further includes an upper electrode assembly, which includes a gas spray head for delivering process gas into the vacuum reaction chamber.

[0026] Optionally, an insulating window is provided above the vacuum reaction chamber, and an inductor coil is provided above the insulating window.

[0027] Furthermore, the present invention also discloses a method for installing a lower electrode assembly, comprising the following steps:

[0028] The first elastic ring and the second elastic ring are meshed together to form an elastic ring assembly, wherein the first elastic ring and the second elastic ring have the features described above.

[0029] A support base is provided, and the elastic ring assembly is disposed around the support base;

[0030] An edge ring assembly is mounted on the outside of the elastic ring assembly.

[0031] Optionally, the installation method is performed at room temperature, wherein the room temperature range is 20 degrees Celsius to 30 degrees Celsius.

[0032] Optionally, at room temperature, the protrusion of the elastic ring assembly near the support base contacts the support base, and the side near the edge ring assembly contacts the edge ring.

[0033] The advantages of this invention are as follows: This invention provides a lower electrode assembly and plasma processing equipment with a large operating temperature range. At least one elastic ring is provided between the edge ring assembly and the support base, and several protrusions are provided on the sidewall of the elastic ring. When the plasma reaction chamber has a high operating temperature, the elastic ring expands significantly due to its higher coefficient of thermal expansion than the support base, and the elastic ring is easily deformed. The protrusions on the sidewall are compressed, which can fully fill the gap between the edge ring assembly and the support base, protecting the edge ring assembly from cracking. When the plasma reaction chamber has a low operating temperature, the various components expand and contract with temperature changes, the gap between the support base and the edge ring assembly increases, the elastic ring returns to its original shape, and the protrusions divide the large gap between the support base and the edge ring assembly into several sub-gap gaps and block plasma from entering, increasing the breakdown voltage that the lower electrode assembly can withstand. The elastic ring structure of this invention can ensure the safe use of the lower electrode assembly within a large operating temperature range. Compared with the prior art, which requires replacing elastic rings of different thicknesses for different operating temperature ranges, the technical solution of this invention improves the consistency and simplicity of the plasma processing equipment. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram of a capacitively coupled plasma processing device is shown.

[0036] Figure 2 A magnified view showing the location of the elastic ring;

[0037] Figure 3 A magnified view of the location of the elastic ring in a high-temperature environment is shown.

[0038] Figure 4 A schematic diagram of a cross-sectional structure of an elastic ring is shown;

[0039] Figure 5 A three-dimensional structural schematic diagram of an elastic ring is shown;

[0040] Figure 6 A partial schematic diagram of the lower electrode assembly with two elastic rings is shown;

[0041] Figure 7 A partial schematic diagram of a lower electrode assembly with two elastic rings is shown in a high-temperature environment.

[0042] Figure 8 A partial schematic diagram of the lower electrode assembly with two elastic rings in a low-temperature environment is shown.

[0043] Figure 9 A schematic diagram of an elastic ring assembly consisting of two meshing elastic rings is shown.

[0044] Figure 10 A schematic diagram of an inductively coupled plasma processing device is shown. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Figure 1 A schematic diagram of a capacitively coupled plasma processing device is shown, including a vacuum-ejectable reaction chamber enclosed by an outer wall 10. The reaction chamber is used to process a substrate 103. Inside the reaction chamber is a lower electrode assembly, used to support the substrate while controlling factors affecting substrate processing, such as substrate temperature and electric field. The lower electrode assembly includes a support base, which includes a metal base 101 and an electrostatic chuck 102 located above the metal base. The metal base 101 contains a temperature control device for controlling the temperature of the substrate above it. The electrostatic chuck 102 supports the substrate 103 and has a DC electrode inside. This DC electrode generates DC adsorption between the back of the substrate and the support surface of the electrostatic chuck to fix the substrate. A focusing ring 50 and an insertion ring 40 located below the focusing ring 50 are arranged around the base and the electrostatic chuck. The focusing ring 50 and the insertion ring 40 constitute an edge ring assembly, which is used to adjust the temperature and electric field distribution in the edge region of the substrate. An elastic ring 100 is disposed between the edge ring assembly and the support base. This elastic ring fills the gap between the edge ring assembly and the support base, preventing plasma discharge within the gap. A plasma confinement ring 108 is disposed around the edge ring assembly, located between the edge ring assembly and the reaction chamber sidewall 105. This confinement ring 108 confines the plasma within the reaction region while allowing gas to pass through. A grounding ring 109, located below the plasma confinement ring, provides electric field shielding to prevent plasma leakage. A bias RF power supply typically applies a bias RF signal to the lower electrode assembly to control the plasma bombardment direction within the reaction chamber. The lower electrode assembly disclosed in this invention can be used for, for example... Figure 1 The capacitively coupled plasma processing device shown.

[0047] exist Figure 1 The capacitively coupled plasma processing apparatus shown includes an upper electrode assembly in addition to the lower electrode assembly. The upper electrode assembly includes a gas spray head 60 for introducing process gas from a gas supply device into the reaction chamber. A high-frequency radio frequency power source applies a high-frequency radio frequency signal to at least one of the upper or lower electrode assemblies to form a radio frequency electric field between the upper and lower electrode assemblies, thereby exciting the process gas in the reaction chamber into plasma and realizing plasma processing of the substrate to be processed.

[0048] Figure 1 The illustrated capacitively coupled plasma processing device can handle substrate etching using various processes. Different processes typically require different reaction chamber temperatures, and the thermal expansion and contraction of components within the reaction chamber vary at different temperatures. The metal base 101 in the support base is primarily made of aluminum alloy, nickel alloy, or other metal materials, while the insertion ring 40 of the edge ring assembly is primarily made of ceramic. When the temperature rises, the thermal expansion of the metal base exceeds that of the insertion ring. If the gap between the edge ring assembly and the support base is small, the expansion of the metal base can easily crack the insertion ring, causing component damage. Conversely, if the gap between the edge ring assembly and the support base is set to accommodate the expansion of the metal base at high temperatures, a larger gap can easily lead to plasma ignition when the temperature inside the reaction chamber decreases, also damaging the components.

[0049] Therefore, the present invention provides a lower electrode assembly that can support a wide operating temperature range. Figure 2 A partially enlarged view showing the location of the elastic ring is provided. In this invention, an elastic ring 100 is disposed between the edge ring assembly 70 and the support base 108. The elastic ring has several protrusions on the side near the support base and / or the side near the edge ring assembly 70. In this embodiment, several protrusions 110 are shown on the side near the support base, and several protrusions 120 are shown on the side near the edge ring assembly 70. When the elastic ring 100 is installed at room temperature, the protrusions 110 and 120 contact the outer wall of the support base and the inner wall of the edge ring assembly, respectively. As the temperature inside the reaction chamber increases, the support base expands outward due to heat. Simultaneously, because the elastic ring also expands due to heat, the protrusions 110 and 120 are compressed against the support base 108 and the edge ring assembly, forming... Figure 3The state is shown. When the temperature decreases, the three components cool and retract, and the protrusions 110 and 120 of the elastic ring recover. When plasma enters the support base 108 and the edge ring assembly, the protrusions can extend the plasma's path, increase the probability of plasma collision, and thus annihilate the charged plasma. At the same time, the elastic ring 100 divides the gap between the support base and the edge ring assembly into two sub-gap gaps. According to Pareto's law, the breakdown voltage in a space is inversely proportional to the gap in that space. The smaller the gap, the greater the voltage that the space can withstand. Therefore, when the two elastic rings of this invention divide a large gap into two sub-gap gaps, the voltage that the lower electrode assembly can withstand is greatly increased. This is beneficial for protecting the lower electrode assembly even when the elastic ring contracts in a low-temperature environment. Compared with an elastic ring without protrusions, the probability of discharge in the gap can be reduced, thus adapting to lower temperature process environments. The lower electrode assembly disclosed in this invention can be safely used in an operating temperature range of -60 degrees Celsius to 200 degrees Celsius.

[0050] In this invention, the protrusions can both obstruct plasma passage during low-temperature processes and reserve space for thermal expansion at high temperatures, thereby increasing the operating temperature range of the lower electrode assembly. Compared to an elastic ring that is flat on both sides, the operating temperature range can be increased by setting a protrusion on only one side. Of course, setting protrusions on both sides can further increase the operating temperature range.

[0051] Figure 4 A cross-sectional structural schematic diagram of an elastic ring 100 is shown. In this invention, the protrusion height and width of protrusions 110 and 120 need to be limited. We label the longitudinal protrusion height of protrusion 110 as h1 and the transverse protrusion width as h2. The height range of h1 is 0.1 mm to 1 mm, and the width range of h2 is 0.1 mm to 0.5 mm. The height and width should not be too small, firstly because small-sized protrusions are difficult to process, and secondly because if the protrusion size is too small, it is equivalent to a flat sidewall, which cannot achieve the purpose of this invention. The height range of h1 is preferably less than 1 mm. If the protrusion height h1 is too high, it may be difficult to flatten the protrusion at high temperatures. If the protrusion cannot be flattened and is consumed in the gap between the sidewall of the elastic ring and the bearing base, the elastic ring will be squeezed outward, causing the edge ring assembly to crack. Meanwhile, if the protrusion width h2 is too long, a larger gap needs to be set between the edge ring assembly and the support base at room temperature to accommodate the elastic ring. Increasing the gap will lead to a higher probability of discharge. Therefore, in this invention, the height range of h1 is set to 0.1 mm to 1 mm, and the width range of h2 is set to 0.1 mm to 0.5 mm. In this invention, the height and width of protrusions 110 and 120 can be inconsistent, but preferably, the height and width ranges of protrusions 110 and 120 are within the ranges of h1 and h2 described above.

[0052] Figure 5 A three-dimensional structural schematic diagram of an elastic ring is shown. In this embodiment, protrusions are provided on both sides of the elastic ring. Protrusion 110 is located on the inner side of the elastic ring and surrounds the bearing base, while protrusion 120 is located on the outer side of the elastic ring and is surrounded by an edge ring assembly. In this embodiment, protrusions 110 and 120 are continuous annular protrusions. In another embodiment, protrusions 110 and 120 can also be set as discontinuous strip-shaped protrusions. The number of protrusions on each side can be the same or different. In this invention, optionally, the number of protrusions on each side is less than or equal to 5. If the number of protrusions on one side is too large, it may result in an excessively high density of protrusions. When the bearing base and the elastic ring expand due to heat, the protrusions cannot be flattened, which can be understood as increasing the thickness of the elastic ring, leaving no space for deformation. At this time, the elastic ring expands outward, causing the edge ring assembly to crack. Therefore, preferably, the number of protrusions on each side is less than or equal to 5. For the same reason, protrusions 110 and 120 are preferably arranged on horizontal planes at different heights. This avoids the elastic ring from expanding laterally and ensures that protrusions of the same lateral width can accommodate greater elastic deformation, thus preventing the edge ring assembly from cracking.

[0053] To further improve the operating temperature range of the lower electrode assembly Figure 6 A partial schematic diagram of a lower electrode assembly with two elastic rings is shown. In this embodiment, components identical to those in the previous embodiment are referred to by the same reference numerals. In this embodiment, the elastic ring assembly 200 includes a first elastic ring 210 and a second elastic ring 220, wherein the first elastic ring 210 surrounds the bearing base 108, the second elastic ring 220 surrounds the first elastic ring 210, and an edge ring assembly surrounds the second elastic ring. In this embodiment, a first protrusion 211 is provided on the outer side of the first elastic ring, and a second protrusion 222 is provided on the inner side of the second elastic ring. The first protrusion 211 and the second protrusion 222 are located on horizontal planes at different heights, and can overlap and interlock during installation to form an engaging configuration. Optionally, after the first protrusion 211 and the second protrusion 222 are assembled, a height difference h3 should be left between adjacent protrusions, such as... Figure 9 As shown, this is to allow space for deformation when protrusions 211 and 222 are compressed, and the height difference can be greater than 0.1 mm.

[0054] In this embodiment, a plurality of protrusions 213 are also provided on the inner side of the first elastic ring 210 to increase the operating temperature range of the lower electrode assembly. A recess 45 for accommodating the elastic ring assembly is provided on the inner side of the edge ring assembly. The elastic ring assembly is at least partially located within the recess, and the top wall of the recess can shield the elastic ring assembly to reduce plasma bombardment. Due to the recess, plasma has difficulty entering the gap between the second elastic ring 220 and the edge ring assembly. Therefore, to control the gap width between the edge ring assembly and the support base, no protrusions are provided on the outer side of the second elastic ring 220 to allow it to fit snugly against the inner wall of the edge ring assembly.

[0055] In this embodiment, the top wall of the recess 45 at least partially covers the second elastic ring 220. In another embodiment, the top wall of the recess 45 may also at least partially cover the first elastic ring 210. The recess may be provided only on the inner wall of the insertion ring 40, or it may be provided on the inner walls of both the insertion ring 40 and the focusing ring 50 as needed. Furthermore, the shape of the insertion ring is not limited to the shape shown in the figure.

[0056] The installation of the lower electrode assembly is typically performed at room temperature, generally between 20 and 30 degrees Celsius, for example, 25 degrees Celsius. During room temperature installation, the first and second elastic rings are first meshed and assembled into an elastic ring assembly. This elastic ring assembly is then fitted around the outer perimeter of the support base, and finally, the edge ring assembly is placed around the elastic ring assembly. During room temperature installation, the third protrusion 213 of the elastic ring assembly contacts the outer wall of the support base, and the flat outer wall of the elastic ring assembly fits snugly against the inner wall of the recess 45 of the edge ring assembly, effectively controlling the gap between the support base and the edge ring assembly.

[0057] When the process temperature inside the reaction chamber is higher than room temperature, the metal base 101, the first elastic ring 210, and the second elastic ring 220 expand due to heat, compressing the protrusions on the elastic ring assembly. When the process temperature reaches a high temperature, such as around 180 degrees Celsius, the protrusions are completely compressed, reaching... Figure 7 As shown, the deformation of the elastic ring assembly and the metal base is mainly absorbed by the gap formed by the lateral width of the protrusion. Therefore, the elastic ring assembly and the metal base will not expand laterally, thus preventing them from squeezing the edge ring assembly outwards and effectively ensuring the safe use of the edge ring assembly. In this embodiment, the lateral width h2 of the protrusion is 0.2 mm and the longitudinal height h1 is 0.35 mm, which can withstand a high temperature of approximately 180 degrees Celsius. Adjusting the lateral width and longitudinal height of the protrusion can achieve safe use at a process temperature of approximately 200 degrees Celsius.

[0058] When the process temperature inside the reaction chamber is below room temperature, the metal base 101, the first elastic ring 210, and the second elastic ring 220 shrink due to the cold. When the process temperature reaches -60 degrees Celsius, it can achieve the following: Figure 8 As shown, the first and second elastic rings divide the gap between the edge ring assembly and the support base into three sub-gap intervals: the gap between the first elastic ring and the support base, the gap between the first and second elastic rings, and the gap between the second elastic ring and the inner wall of the recess 45. According to Pareto's law, the breakdown voltage within a space is inversely proportional to the gap in that space; the smaller the gap, the greater the voltage that can be withstood within the space. Therefore, when the two elastic rings of this invention divide a large gap into three sub-gap intervals, the voltage that the lower electrode assembly can withstand is greatly increased. This is beneficial for protecting the lower electrode assembly even when the elastic rings contract in low-temperature environments.

[0059] in Figure 8 The elastic ring 210 near the base may not have a protrusion facing the outer wall of the base, but only a protrusion facing the second elastic ring 220. This structure can also avoid high voltage discharge, while reserving expansion space for the base and each elastic ring.

[0060] In this embodiment, the parameter settings for the lateral width h2 and longitudinal height h1 of the protrusion are the same as described above. Figure 4 The limitations are the same, so they will not be repeated here.

[0061] The technical solution of the lower electrode assembly disclosed in this invention, by providing a protrusion on at least one side of the elastic ring, can increase the operating temperature range of the lower electrode assembly. The gap formed by the lateral width of the protrusion provides space for deformation in high-temperature environments. In low-temperature environments, the protrusion can divide the gap between the edge ring assembly and the support base into sub-gap spaces. At the same time, the protrusion also acts as an obstacle in the plasma passage path, promoting plasma annihilation and further reducing the probability of plasma ignition. Therefore, the elastic ring structure of this invention can ensure the safe use of the lower electrode assembly within a wider operating temperature range. Compared with the prior art, which requires replacing elastic rings of different thicknesses for different operating temperature ranges, the technical solution of this invention improves the consistency and simplicity of plasma processing equipment.

[0062] The lower electrode assembly described above can also be used for, for example Figure 10In the inductively coupled plasma processing apparatus shown, in this embodiment, the lower electrode assembly has the structure described above, which will not be repeated here. In addition, an insulating window 130 is provided above the reaction chamber, and an inductor coil 140 is provided above the insulating window. A high-frequency radio frequency power supply 145 applies a radio frequency signal to the inductor coil 140, causing the inductor coil 140 to generate an alternating magnetic field, inducing an alternating electric field within the reaction chamber, thereby achieving plasma dissociation of the process gas entering the reaction chamber. In this embodiment, the process gas can be injected into the reaction chamber from the side wall, or a gas injection port can be provided on the insulating window to accommodate the process gas. A bias radio frequency power supply is applied to the lower electrode assembly through a bias radio frequency matching to control the energy distribution of the plasma.

[0063] The lower electrode assembly disclosed in this invention is not limited to the plasma processing apparatuses of the two embodiments described above, but can also be applied to other plasma processing apparatuses, which will not be elaborated here.

[0064] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A lower electrode assembly for supporting a substrate to be processed, comprising a support base and an edge ring assembly surrounding the support base, the edge ring assembly comprising: A focusing ring is disposed around the substrate and the support base; An insertion ring, located below the focusing ring, is disposed around the support base; characterized in that... A first elastic ring is provided between the edge ring assembly and the support base. The first elastic ring has a plurality of protrusions on the side facing the support base and the side facing the edge ring assembly. The plurality of protrusions divide the gap between the support base and the edge ring assembly into a plurality of sub-gap gaps, which can decrease as the temperature of the support base increases.

2. The lower electrode assembly as described in claim 1, characterized in that: A second elastic ring is arranged around the periphery of the first elastic ring, and the second elastic ring has a plurality of protrusions on the side of the first elastic ring and / or the side of the edge ring assembly.

3. The lower electrode assembly as described in claim 2, characterized in that: The first elastic ring has a plurality of first protrusions on the side near the edge ring assembly, and the second elastic ring has a plurality of second protrusions on the side near the first elastic ring. The first protrusions and the second protrusions are located in horizontal planes at different heights.

4. The lower electrode assembly as described in claim 3, characterized in that: The first elastic ring has several third protrusions on the side near the bearing base.

5. The lower electrode assembly as described in claim 4, characterized in that: The first protrusion and the third protrusion are located in horizontal planes at different heights.

6. The lower electrode assembly as described in claim 4, characterized in that: At least one of the first protrusion, the second protrusion, and the third protrusion is a continuous annular structure.

7. The lower electrode assembly as described in claim 4, characterized in that: At least one of the first protrusion, the second protrusion, and the third protrusion is a discontinuous band structure.

8. The lower electrode assembly as described in claim 4, characterized in that: The lateral protrusion width of the first protrusion, the second protrusion, and the third protrusion is between 0.1mm and 0.5mm.

9. The lower electrode assembly as described in claim 4, characterized in that: The longitudinal protrusion height of the first protrusion, the second protrusion, and the third protrusion is between 0.1 mm and 1 mm.

10. The lower electrode assembly as described in claim 2, characterized in that: The number of protrusions on each side of the first elastic ring and the second elastic ring is less than or equal to 5.

11. The lower electrode assembly as described in claim 2, characterized in that: The edge ring assembly has a recessed portion on the inner side near the bearing base, and the second elastic ring is at least partially located within the recessed portion.

12. The lower electrode assembly as claimed in claim 11, characterized in that: The edge ring assembly has a recessed portion on the inner side near the bearing base, and the first elastic ring is at least partially located within the recessed portion.

13. The lower electrode assembly as described in claim 11 or 12, characterized in that: The second elastic ring does not have a protrusion on the side near the edge ring assembly.

14. The lower electrode assembly as claimed in claim 2, characterized in that: The first elastic ring and the second elastic ring are at least one of hard rubber, epoxy resin or Teflon.

15. A plasma processing apparatus, comprising a vacuum reaction chamber, characterized in that: The vacuum reaction chamber is provided with a lower electrode assembly as described in any one of claims 1-14.

16. The plasma processing apparatus as described in claim 15, characterized in that: The supporting base includes a metal base and an electrostatic chuck located above the metal base.

17. The plasma processing apparatus as described in claim 15, characterized in that: The operating temperature range of the vacuum reaction chamber is -60 degrees Celsius to 200 degrees Celsius.

18. The plasma processing apparatus as described in claim 15, characterized in that: When the operating temperature range of the vacuum reaction chamber is lower than room temperature, several protrusions of the first elastic ring are in close contact with the outer wall of the support base or the inner wall of the edge ring assembly, so as to divide the gap between the edge ring assembly and the support base into two mutually isolated sub-gap.

19. The plasma processing apparatus as described in claim 15, characterized in that: The vacuum reaction chamber also includes an upper electrode assembly, which includes a gas spray head for supplying process gas into the vacuum reaction chamber.

20. The plasma processing apparatus as described in claim 15, characterized in that: An insulating window is provided above the vacuum reaction chamber, and an inductor coil is provided above the insulating window.

21. A method for installing a lower electrode assembly, characterized in that: Includes the following steps: The first and second elastic rings as described in any one of claims 2-14 are meshed and assembled into an elastic ring assembly; A support base is provided, and the elastic ring assembly is disposed around the support base; An edge ring assembly is mounted on the outside of the elastic ring assembly.

22. The installation method as described in claim 21, characterized in that: The installation method is performed at room temperature, which is between 20 and 30 degrees Celsius.

23. The installation method as described in claim 22, characterized in that: At room temperature, the protrusion of the elastic ring assembly near the support base contacts the support base, and the side near the edge ring assembly contacts the edge ring.

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