TWI759887B - Plasma processing device, lower electrode assembly, electrostatic chuck - Google Patents

Abstract

The invention discloses a plasma processing device, a lower electrode assembly thereof, and an electrostatic chuck, wherein the electrostatic chuck is used to support a substrate to be processed in a reaction chamber of the plasma processing device, and the electrostatic chuck comprises a surface extending through the electrostatic chuck to The lower surface is used to pass a plurality of air holes for cooling gas between the electrostatic chuck and the substrate to be processed; at least one hole plug is filled in the air hole; Through holes, the inner diameter of the through holes is smaller than the inner diameter of the air holes. In the present invention, at least one hole plug is filled in the air hole of the electrostatic chuck, and a plurality of through holes are arranged on the hole plug, so as to ensure the temperature uniformity of the substrate on the electrostatic chuck, and further avoid the electrostatic chuck. The dissociation of the cooling gas in the pores causes the inner wall of the pores to be broken down, and impurity particles are generated in the pores.

Description

Plasma processing device, lower electrode assembly, electrostatic chuck

The present invention relates to the field of semiconductor processing equipment, in particular to a plasma processing device and its lower electrode assembly and electrostatic chuck.

In the plasma treatment process, electrostatic chucks are often used to fix, support and transport substrates to be processed. The electrostatic chuck is arranged in the reaction chamber, which uses electrostatic attraction instead of mechanical means to fix the substrate, which can reduce the possible mechanical loss to the substrate, and make the electrostatic chuck and the substrate completely contact, which is conducive to heat conduction. During the reaction, the reaction gas is introduced into the reaction chamber, and radio frequency power is applied to the reaction chamber. Usually, the radio frequency power is applied to the base below the electrostatic chuck. The radio frequency power mainly includes the radio frequency source power and the radio frequency bias power. The source power and the radio frequency bias power work together to ionize the reaction gas to generate plasma, and the plasma reacts with the substrate to complete the process of the substrate.

In the plasma treatment process, in order to prevent the substrate from overheating, a cooling gas such as helium is often used to remove the heat on the substrate. In order to achieve the above purpose, the electrostatic chuck is usually provided with a plurality of air holes to pass cooling gas such as helium gas between the electrostatic chuck and the substrate to remove the heat on the substrate. However, in the actual reaction process, it is found that the inner wall of the air hole of the electrostatic chuck is easily broken down, thereby generating impurity particles in the air hole, and finally contaminating the substrate.

In the plasma treatment process, the plasma etching process is very sensitive to temperature, and the temperature control is very strict. It is necessary to precisely control the temperature, and the temperature uniformity directly affects the etching uniformity. Therefore, how to ensure that the cooling gas diffuses evenly on the surface of the electrostatic chuck, and then ensures the uniformity of the substrate on the electrostatic chuck. In the case of temperature uniformity, it is a technical problem to be solved by the present invention to avoid the dissociation of cooling gas in the pores of the electrostatic chuck, and the breakdown of the inner wall of the pores and the generation of impurity particles in the pores.

The purpose of the present invention is to provide a plasma processing device, its lower electrode assembly, and an electrostatic chuck, so as to prevent the cooling gas such as helium in the air holes of the electrostatic chuck from being ionized or broken down under the action of radio frequency power to generate plasma , while ensuring the temperature uniformity of the substrate on the electrostatic chuck.

In order to achieve the above object, the present invention provides an electrostatic chuck for supporting a substrate to be processed in a reaction chamber of a plasma processing device, which comprises passing through the upper surface to the lower surface of the electrostatic chuck for feeding the electrostatic chuck. A plurality of air holes through which cooling gas is passed between the disc and the substrate to be processed; at least one hole plug is filled in the air hole; smaller than the inner diameter of the air hole.

In the above electrostatic chuck, when the number of hole plugs in the air hole is one, the aspect ratio of the through hole is greater than 10.

In the above electrostatic chuck, the diameter of the through hole is 0.5mm~3mm.

In the above electrostatic chuck, when the number of hole plugs in the air hole is plural, the hole plugs are arranged in layers, and the through holes of the hole plugs of two adjacent layers are arranged in alignment or in a staggered arrangement.

In the above electrostatic chuck, the diameter of the through hole is 10 μm˜3 mm.

In the above electrostatic chuck, the number of through holes on each hole plug is 2-50.

In the above electrostatic chuck, one or more hole plugs are completely or partially filled into the air holes.

In the above electrostatic chuck, the material of the hole plug is ceramic.

In the above electrostatic chuck, the through hole is obtained by machining or laser drilling.

In the above electrostatic chuck, the distance between the diameter of the through hole and the adjacent through hole is controllable.

The present invention also provides a lower electrode assembly, which includes the above-mentioned electrostatic chuck, a base for supporting the electrostatic chuck is arranged below the electrostatic chuck, an adhesive layer is arranged between the electrostatic chuck and the base, and the electrostatic chuck is provided with a base for supporting the electrostatic chuck. The air holes on the chuck go down through the adhesive layer and extend to a certain depth in the base.

In the above-mentioned lower electrode assembly, the base is provided with cooling pipes for conveying cooling gas and communicating with the air holes.

The present invention also provides a plasma processing device, which comprises: a reaction chamber, wherein the above-mentioned lower electrode assembly is arranged in the reaction chamber.

Compared with the prior art, the present invention has the following beneficial effects: The hole plug provided by the invention is convenient for machining or laser drilling, and the uniformity of the diameter of the through hole on the hole plug and the distance between the through holes is controllable in processing, and the surface of the electrostatic chuck is realized by the cooling gas. The diffusion distribution is uniform, which in turn ensures the temperature uniformity of the substrate on the electrostatic chuck.

On the one hand, the present invention inserts a hole plug with a plurality of through holes into the air holes of the existing electrostatic chuck. Since the through holes on the hole plug are much smaller than the existing air hole diameter, under the condition of a constant cooling gas supply pressure , compared with the cooling gas pressure in the existing air hole, the cooling gas pressure in the through hole of the hole plug will be significantly reduced, and then the distance d between the poles and the product Pd of the air pressure P are adjusted to the left of the lowest point of the helium Paschen curve, so that the cooling The breakdown voltage that the gas can withstand is significantly increased, preventing the cooling gas from breaking down the inner wall of the gas hole due to dissociation.

On the other hand, the hole plug through hole with a significantly reduced pore size is not easy to make the plasma generated by the ionization of the reactive gas penetrate from the gas hole to form an electrical circuit, so as to avoid the dissociation of the cooling gas in the gas hole caused by this, and finally cause the electrostatic chuck. The problem that the inner wall of the air hole is broken down. Further, when the number of hole plugs in the air hole is one, the depth-to-width ratio of the through hole is preferably greater than 10, so that the plasma generated by the ionization of the reactive gas is not easy to penetrate the hole plug, and the length, depth and width will further significantly increase the probability of ion collision. Catching electrons or losing electrons will cause the plasma to be extinguished, avoiding the problem of breakdown of the inner wall of the electrostatic chuck air hole caused by this. Further, when the number of hole plugs in the air hole is plural, the through holes of the hole plugs of two adjacent layers can be aligned, or they can be staggered and fixed to form a labyrinth structure. The characteristics of movement, so as to achieve the purpose of preventing the plasma generated by the ionization of the reaction gas from passing through the hole plug, cutting off the possible electrical circuit, and avoiding the dissociation or breakdown of the cooling gas in the gas hole.

To sum up, in the present invention, at least one hole plug is filled in the air hole of the electrostatic chuck, and the hole plug is provided with a plurality of through holes with controllable spacing and diameter, so as to ensure the diffusion of cooling gas on the surface of the electrostatic chuck. Evenly distributed, thus ensuring the temperature uniformity of the substrate on the electrostatic chuck, it further avoids the breakdown of the inner wall of the air hole caused by the dissociation of the cooling gas in the air hole of the electrostatic chuck, and the generation of impurity particles in the air hole. question.

1: Electrostatic chuck

2: Base

3: Adhesive layer

11: Air holes

12: hole plug

13: Through hole

21: Cooling pipes

22: Cavity

1 is a schematic diagram of the dissociation of helium gas inside the air hole in the lower electrode assembly; FIG. 2 is a Paschen curve diagram of helium gas; FIG. 3 is a schematic structural diagram of an embodiment of a hole plug in the present invention; Another embodiment of the hole plug is a schematic view of the structure of the individual and combined state; FIG. 5 is a schematic view of the structure of an embodiment of the lower electrode assembly of the present invention.

The present invention will be further described below with reference to the accompanying drawings through specific embodiments. These embodiments are only used to illustrate the present invention and not to limit the protection scope of the present invention.

In the process of realizing the present invention, the inventor found that the reason for the breakdown of the inner wall of the air hole 11 of the electrostatic chuck 1 in the prior art lies in the following two aspects:

(1) During the reaction process, the air holes 11 on the electrostatic chuck 1 will be directly under the action of radio frequency power, thereby causing the cooling gas such as helium inside the air holes 11 to be ionized or broken down under the action of the radio frequency power. Plasma, the plasma reacts with the inner wall material, and produces a corrosion effect on the inner wall of the air hole 11, and at the same time, some impurity particles are generated in the air hole 11, which will further pollute the substrate.

(2) During the reaction process, the plasma generated by the ionization of the reactive gas will also pass through the air hole 11 on the electrostatic chuck 1, and finally form an electrical circuit, which will also cause the ionization or ionization of the cooling gas such as helium in the air hole 11. It is broken down, so that the inner wall of the air hole 11 is easily broken down, thereby generating impurity particles in the air hole 11, and finally contaminating the substrate.

FIG. 1 shows a schematic diagram of a lower electrode assembly. As shown in FIG. 1 , there is a base 2 under the reaction chamber in the plasma processing apparatus. The base 2 is used to support the electrostatic chuck 1 and simultaneously serves as the lower electrode of the reaction An adhesive layer 3 is arranged between the electrodes and the electrostatic chuck. The electrostatic chuck 1 contains a DC electrode (not shown in the figure) which is connected to the DC power supply and uses the Coulomb force generated by static electricity to firmly adsorb the substrate to be processed on the static electricity. on chuck 1. The lower electrode assembly shown in the present invention is suitable for any plasma processing apparatus that needs to control the temperature of the processing substrate, such as capacitively coupled plasma processing apparatus and inductively coupled plasma processing apparatus. When the lower electrode assembly is applied to a capacitively coupled plasma processing device, the plasma processing device further includes an upper electrode installed at the top of the reaction chamber and corresponding to the lower electrode, and the upper electrode usually simultaneously serves as a gas distribution plate for inputting reaction gas. After partial or full application of RF energy to the upper and lower electrodes, power on and off Plasma will be generated between the poles to perform plasma treatment on the substrate, and the gas between the two poles of the electric field will undergo gas breakdown and dissociation under a certain pressure.

Figure 2 shows the Paschen curve of helium, that is, the relationship between the breakdown voltage U (unit: volt) of helium gas and the product Pd (unit: Torr·cm) of the distance d between the two poles and the gas pressure P (unit: Torr·cm). It can be seen from the curve that both the distance between the two poles and the air pressure are factors that determine the breakdown voltage in the air hole 11 on the electrostatic chuck 1 . When the Pd value of helium is between 1-2 Torr·cm, its breakdown voltage is the lowest. To increase the breakdown voltage of the gas to make it difficult for the gas to be broken down or ionized, the Pd value can be reduced so that it falls into the nearly vertical curve segment at the left end of the curve.

Based on the above content, in view of the reason (1) that the inner wall of the air hole 11 is broken down, the idea adopted in the present invention is to adjust the product of the distance between the two poles and the air pressure to the lowest value of the helium Paschen curve by reducing the pressure P in the air hole 11 Click to the left to increase the breakdown voltage that the cooling gas can withstand. In addition, in view of the reason (2) that the inner wall of the air hole 11 is broken down, the idea adopted in the present invention is to prevent the plasma generated by the ionization of the reactive gas from penetrating from the air hole 11, thereby forming an electrical circuit, resulting in the cooling gas in the air hole 11. dissociation, to avoid the problem of breakdown of the inner wall of the air hole 11 of the electrostatic chuck 1 caused by this.

Based on the above inventive idea, the present invention provides an electrostatic chuck 1 for supporting a substrate to be processed in a reaction chamber of a plasma processing device. A plurality of air holes 11 for passing cooling gas between the electrostatic chuck 1 and the substrate to be processed; at least one hole plug 12 is filled in the air hole 11; There are a plurality of through holes 13 on the surface, and the inner diameter of the through holes 13 is smaller than the inner diameter of the air holes 11 .

In this embodiment, by inserting the hole plug 12 with a plurality of through holes 13 into the air holes 11 of the existing electrostatic chuck 1 , since the through holes 13 on the hole plug 12 are much smaller than the existing air holes 11, the When the cooling gas supply pressure is constant, the cooling gas pressure in the through hole 13 will be significantly reduced relative to the cooling gas pressure in the existing air hole 11, and then the product Pd of the distance d between the two poles and the air pressure P is adjusted to helium Paschen. On the left side of the lowest point of the curve, the breakdown voltage that the cooling gas can withstand is significantly increased, which prevents the cooling gas from breaking down the inner wall of the air hole 11 due to dissociation. At the same time, the through-holes 13 with significantly reduced pore diameters are not easy for the plasma generated by the ionization of the reactive gas to pass through the air holes 11 to form an electrical circuit, so as to avoid the dissociation of the cooling gas in the air holes 11 caused by this, and finally cause the electrostatic chuck 1 The problem that the inner wall of the air hole 11 is broken down. In addition, in the semiconductor manufacturing process, the plasma etching process is very sensitive to temperature, and the temperature control is very strict. It is necessary to precisely control the temperature, and the temperature uniformity directly affects the etching uniformity. The hole plug 12 provided by the present invention is convenient for machining. By processing a plurality of through holes 13 with controllable spacing and diameter on the hole plug 12, the uniform diffusion and distribution of the cooling gas on the surface of the electrostatic chuck 1 is realized, thereby ensuring the Temperature uniformity of the substrate on the electrostatic chuck 1 .

Considering the controllability of actual machining and the particularity of the plasma treatment process, the material of the hole plug 12 provided by the present invention is preferably selected from ceramics, so as to achieve the diameter of the through hole 13 under the condition of satisfying the plasma treatment process And the gap between the through holes 13 is easier to control. The number of the through holes 13 on each hole plug 12 provided by the present invention is preferably 2-50. The processing quantity of the through holes 13 on the hole plug 12 should not be too small, otherwise the cooling gas flowing in is too small and the substrate on the electrostatic chuck 1 cannot be sufficiently cooled; the processing quantity of the through holes 13 on the hole plug 12 should not be too much, otherwise additional processing will be added The complexity of the invention does not further significantly increase the technical purpose to be achieved by the present invention. In addition, in the air hole 11 of each electrostatic chuck 1, one or more hole plugs 12 can be completely or partially filled, which can avoid the problem of the inner wall of the air hole 11 of the electrostatic chuck 1 being broken down.

As shown in FIG. 3 , in a preferred embodiment, when the number of hole plugs 12 in the air hole 11 is one, the aspect ratio of the through hole 13 is preferably greater than 10, so that the plasma generated by the ionization of the reaction gas is not easily permeable. The length, depth and width of the hole plug 12 will further significantly increase the probability of ion collision. Catching electrons or losing electrons will cause the plasma to be extinguished, thereby avoiding the problem of breakdown of the inner wall of the air hole 11 of the electrostatic chuck 1. exist On this basis, the diameter of the through hole 13 on the hole plug 12 is preferably 0.5 mm˜3 mm. The selection of the outer diameter of less than 3 mm is more beneficial to prevent the plasma generated by gas ionization from passing through the hole plug 12, thereby preventing the electrostatic chuck 1 from being broken down due to the formation of an electrical circuit. In this embodiment, since a hole plug 12 with a plurality of through holes 13 is arranged in the air hole 11 , and the inner diameter of the through hole 13 is smaller than that of the air hole 11 , the plasma discharge phenomenon that may occur in the air hole 11 is effectively reduced. The smaller the diameter of the through hole 13 is, the better the high voltage resistance capability of the electrostatic chuck is improved. Due to the limitation of traditional machining, it is difficult to machine the through hole 13 below 0.5 mm to a larger depth.

As shown in FIG. 4A to FIG. 4E , in another preferred embodiment, the number of hole plugs 12 in the air hole 11 is set to a plurality, and at this time, a plurality of hole plugs 12 can be stacked to fill the air holes. 11 required height. In addition to selecting the traditional machining method, the present invention can also use a laser device to drill holes on the ceramic hole plug 12, which can realize the processing of holes with a diameter of less than 0.5 mm, up to a micro hole of 10 μm. The diameter is preferably 10 μm to 3 mm. However, the thickness of the hole plug 12 made of ceramic material is limited by laser drilling and the like, and the processing of the hole plug 12 with a thickness exceeding 3 mm cannot be realized. A plurality of hole plugs 12 can be designed, and a plurality of through holes 13 are distributed in an array on each hole plug 12 , which are finally stacked and inserted into the air holes 11 of the electrostatic chuck 1 . The through holes 13 of the hole plugs 12 of each layer can be aligned or arranged in a staggered manner and fixed in position to form a labyrinth structure as shown in FIG. 4D to FIG. 4E , using the feature that the plasma can only move linearly, so as to prevent the reaction gas The purpose of the ionized plasma penetrates the hole plug 12 , cuts off possible electrical circuits, and prevents the cooling gas in the air hole 11 from dissociating or being broken down. The hole plug 12 in the electrostatic chuck 1 provided in this embodiment adopts a gas circuit with a special labyrinth structure, which effectively and completely blocks the electric circuit of the plasma generated by the ionization of the reaction gas.

As shown in FIG. 5 , the present invention also provides a lower electrode assembly, which includes the above-mentioned electrostatic chuck 1 , a base 2 for supporting the electrostatic chuck is arranged below the electrostatic chuck 1 , the electrostatic chuck 1 and the base are An adhesive layer 3 is arranged between 2 , and the air holes 11 on the electrostatic chuck 1 penetrate the adhesive layer 3 downward and extend to a certain depth of the base 2 . Since the air hole 11 of the electrostatic chuck 1 in this embodiment is filled with one or a plurality of stacked The hole plug 12 described above. In this embodiment, by processing a plurality of through holes 13 on the hole plug 12, on the basis of realizing uniform diffusion and distribution of the cooling gas on the surface of the electrostatic chuck 1, the air pressure in the through holes 13 is significantly reduced, and the distance between the two poles d and The product Pd of the air pressure P is adjusted to the left of the lowest point of the helium Paschen curve, so that the breakdown voltage that the cooling gas can withstand is significantly increased, and the resulting breakdown of the cooling gas to the inner wall of the air hole 11 due to dissociation is avoided; Taking advantage of the fact that the plasma can only move linearly and will be extinguished due to excessive collisions during the movement, the plasma generated by the ionization of the reaction gas is blocked from passing through the pores 11 to form an electrical circuit, thereby avoiding the cooling gas caused by this. The problem of breakdown of the inner wall of the air hole 11 due to dissociation.

Further, the base 2 is provided with a cooling pipe 21 for conveying cooling gas and communicating with the air hole 11 , which only needs to be obtained by machining in the base 2 without additional piping arrangement, which greatly reduces the complexity of the lower electrode assembly. . Furthermore, a cavity 22 can be arranged between the cooling pipe 21 and the air hole 11 to stabilize the pressure of the cooling gas, which is more beneficial to realize the uniform diffusion and distribution of the cooling gas on the surface of the electrostatic chuck 1, thereby ensuring the electrostatic chuck 1 Temperature uniformity on the substrate is achieved to promote uniformity of substrate etching.

The present invention also provides a plasma processing device, which comprises: a reaction chamber, wherein the above-mentioned lower electrode assembly is arranged in the reaction chamber. Based on the same reason, the plasma processing apparatus provided by the present invention can avoid the problem of impurity particles being generated in the pores due to the breakdown of the inner walls of the pores caused by dissociation of the cooling gas in the pores of the electrostatic chuck.

The hole plug 12 provided by the present invention is convenient for machining. By machining a plurality of through holes 13 with controllable spacing and diameter on the hole plug 12, the cooling gas can be evenly diffused and distributed on the surface of the electrostatic chuck 1, thereby ensuring static electricity. Temperature uniformity of the substrate on the chuck 1.

On the one hand, in the present invention, the hole plug 12 having a plurality of through holes 13 is inserted into the air hole 11 of the existing electrostatic chuck 1. Since the through hole 13 on the hole plug 12 is much smaller than the diameter of the existing air hole 11, the cooling When the gas supply pressure is constant, the cooling gas pressure in the through hole 13 will be significantly reduced relative to the cooling gas pressure in the existing air hole 11, and then the distance d between the two poles and the product Pd of the gas pressure P are adjusted to the value of the helium Paschen curve. To the left of the lowest point, the breakdown voltage that the cooling gas can withstand is significantly increased, which prevents the cooling gas from penetrating the inner wall of the air hole 11 due to dissociation.

On the other hand, the through holes 13 with significantly reduced pore size are not easy for the plasma generated by the ionization of the reactive gas to pass through the pores 11 to form an electrical circuit, so as to avoid the dissociation of the cooling gas in the pores 11 caused by this, and eventually lead to electrostatic jamming. The problem that the inner wall of the air hole 11 of the disk 1 is broken down. Further, when the number of hole plugs 12 in the air hole 11 is one, the aspect ratio of the through hole 13 is preferably greater than 10, so that the plasma generated by the ionization of the reaction gas is not easy to pass through the hole plug 12, and the length, depth and width will further significantly increase the ion The probability of collision, the capture of electrons or the loss of electrons will lead to the extinction of the plasma, which avoids the problem that the inner wall of the air hole 11 of the electrostatic chuck 1 is broken down. Furthermore, when the number of the hole plugs 12 in the air hole 11 is plural, the through holes 13 of the hole plugs 12 of the two adjacent layers can be aligned or arranged in a staggered manner to form a labyrinth structure, which can only move linearly by using the plasma. Therefore, the purpose of preventing the plasma generated by the ionization of the reaction gas from penetrating the hole plug 12 is realized, and the possible electrical circuit is cut off, so as to avoid dissociation or breakdown of the cooling gas in the gas hole 11 .

To sum up, in the present invention, at least one hole plug is filled in the air hole of the electrostatic chuck, and the hole plug is provided with a plurality of through holes, so as to ensure that the cooling gas diffuses and distributes evenly on the surface of the electrostatic chuck, thereby ensuring static electricity. When the temperature of the substrate on the chuck is uniform, the problem that the inner wall of the air hole is broken down due to the dissociation of the cooling gas in the air hole of the electrostatic chuck and the generation of impurity particles in the air hole is further avoided. Compared with other porous materials, the hole plug made by the present invention has more uniform distribution of through holes and is not easy to be blocked.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be construed as limiting the present invention. in the technical field of Various modifications and substitutions to the present invention will be apparent to those of ordinary skill after reading the foregoing. Therefore, the protection scope of the present invention should be defined by the appended claims.

1: Electrostatic chuck

2: Base

3: Adhesive layer

11: Air holes

12: hole plug

21: Cooling pipes

22: Cavity

Claims (10)

An electrostatic chuck is used for supporting a substrate to be processed in a reaction chamber of a plasma processing device, which comprises passing through the upper surface to the lower surface of the electrostatic chuck for feeding the electrostatic chuck and the substrate to be processed. A plurality of air holes through which cooling gas is passed between; each of the plurality of air holes is filled with at least one hole plug; the hole plug is provided with a plurality of through holes passing through the upper surface to the lower surface of the hole plug, the The inner diameter of each of the plurality of through holes is smaller than the inner diameter of each of the plurality of air holes; wherein when the number of hole plugs in each of the plurality of air holes is plural, the hole plugs are arranged in layers , each of the plurality of through holes of the hole plugs of two adjacent layers is aligned or arranged in a staggered manner. The electrostatic chuck according to claim 1, wherein each of the plurality of through holes has a diameter of 10 μm˜3 mm. The electrostatic chuck according to claim 1, wherein the number of the plurality of through holes on each hole plug is 2-50. The electrostatic chuck of claim 1, wherein one or more of the hole plugs are completely or partially filled into each of the plurality of air holes. The electrostatic chuck according to claim 1, wherein the material of the hole plug is ceramic. The electrostatic chuck according to claim 1, wherein the plurality of through holes are obtained by machining or laser drilling. The electrostatic chuck according to claim 1, wherein the distance between the diameter of each of the plurality of through holes and each of the adjacent through holes is controllable. A lower electrode assembly, comprising the electrostatic chuck as described in any one of claim 1 to claim 7, a base for supporting the electrostatic chuck is arranged below the electrostatic chuck, the electrostatic chuck An adhesive layer is arranged between the base and the electrostatic chuck, and a plurality of air holes on the electrostatic chuck penetrate downward through the adhesive layer and extend to a certain depth of the base. The lower electrode assembly according to claim 8, wherein the base is provided with a cooling pipe which conveys cooling gas and communicates with the plurality of air holes. A plasma processing device, comprising: a reaction chamber, the lower electrode assembly according to claim 8 is arranged in the reaction chamber.

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