Lower electrode assembly and plasma processing device thereof

Abstract

The utility model discloses a lower electrode assembly and a plasma processing device thereof, and the lower electrode assembly comprises a pedestal which is provided with a first through hole, and the first through hole is communicated with a gas source; the dielectric layer is arranged on the base, the top surface of the dielectric layer is used for bearing a wafer, a second through hole is formed in the dielectric layer, a spiral plug is arranged in the second through hole, an arc-shaped gas channel is formed in the spiral plug or between at least part of the side wall of the spiral plug and the side wall of the second through hole, and the arc-shaped gas channel is provided with a gas inlet communicated with the first through hole; and an air outlet communicating with the top space of the dielectric layer. The lower electrode assembly has the advantages that the walking path of gas is lengthened through the spiral plug, the gas discharge path is increased, meanwhile, the collision probability of charged particles and the side wall of the gas channel is increased through the arc-shaped gas channel, the collision extinguishing probability of the charged particles is increased, the phenomenon of through hole breakdown or arc ignition of the dielectric layer is avoided, and the service life of the lower electrode assembly is prolonged. And the stability of the environment in the cavity is ensured.

Description

Technical Field

[0001] The utility model relates to the field of semiconductor equipment, in particular to a lower electrode assembly and a plasma processing device thereof. Background Art

[0002] In the production process of semiconductor chips, a large amount of micro-machining is required, among which the commonly used micro-machining processes include plasma etching, physical vapor deposition, chemical vapor deposition and other methods. The process of micro-machining manufacturing is often accompanied by plasma-assisted processes. These processes are generally carried out in a vacuum reaction chamber. Among them, the plasma etching process in the plasma-assisted process is the key process for processing the wafer into the designed pattern. The working principle of the plasma etching process is generally to introduce a reaction gas containing an appropriate etchant or deposition source gas into the vacuum reaction chamber, and then input radio frequency energy into the vacuum reaction chamber to activate the reaction gas to ignite or maintain the plasma, and then process the semiconductor substrate.

[0003] During the entire plasma etching process, the reaction environment for wafer processing is very harsh. Factors such as the stability of the process environment in the reaction chamber, the flow and distribution of the process gas, the heating temperature field of the wafer, and the pressure distribution in the reaction chamber are all crucial. They directly or indirectly determine the quality of wafer surface treatment. However, in actual applications, it is usually difficult to ensure the stability of the process environment in the chamber. This may be due to factors such as changes in the RF environment in the chamber. For example, during the process, the electrostatic chuck will be subjected to a large partial pressure in a high-power operating environment. The gas in the pores of the electrostatic chuck may be ionized under the action of the partial pressure, resulting in pore wall breakdown. Severe cases may also cause problems such as electrostatic chuck discharge, resulting in instability of the process environment in the chamber and affecting the processing effect of the wafer surface. Therefore, it is necessary to improve the existing equipment.

[0004] It is to be understood that the above statements merely provide background technology related to the present invention and do not necessarily constitute prior art. Utility Model Content

[0005] Based on the above-mentioned technical problems, the purpose of the utility model is to provide a lower electrode assembly and a plasma processing device thereof, wherein the lower electrode assembly has an arc-shaped gas channel in the second through hole of the dielectric layer through a spiral plug, and the arc-shaped gas channel lengthens the travel path of the gas in the second through hole, thereby increasing the gas discharge path. At the same time, the arc-shaped gas channel increases the collision probability of charged particles with the side walls of the gas channel, thereby increasing the probability of charged particles being extinguished by collision, which helps to avoid through-hole breakdown or arc ignition in the dielectric layer, thereby ensuring the stability of the environment in the cavity.

[0006] In order to achieve the above object, the utility model is implemented through the following technical solutions:

[0007] A lower electrode assembly, comprising:

[0008] A base having a first through hole, wherein the first through hole is connected to a gas source;

[0009] A dielectric layer is arranged on the base, and its top surface is used to support the wafer. The dielectric layer is provided with a second through hole, and a spiral plug is arranged in the second through hole. An arc-shaped gas channel is provided between the interior of the spiral plug and / or at least a part of the side wall of the spiral plug and the side wall of the second through hole, and the gas channel has an air inlet connected to the first through hole, and an air outlet connected to the top space of the dielectric layer.

[0010] Optionally, the arc-shaped gas passage is a gas passage extending in a spiral shape.

[0011] Optionally, the spiral plug comprises a plurality of spiral blocks arranged from top to bottom, each of the spiral blocks is provided with an arcuate sub-channel running through the top and bottom thereof, and the arcuate sub-channels in adjacent spiral blocks are interconnected to form the arcuate gas channel.

[0012] Optionally, the arc-shaped gas channel includes a first gas channel and a second gas channel, a through hole is opened on the spiral plug to form the first gas channel, the second gas channel is formed between the side wall of the spiral plug and the side wall of the second through hole, and the first gas channel is connected to the second gas channel.

[0013] Optionally, the side wall of the second through hole is an arc-shaped plane structure, and an arc-shaped groove is provided on the side wall of the screw plug, and the arc-shaped gas channel is formed between the arc-shaped groove on the side wall of the screw plug and the side wall of the second through hole.

[0014] Optionally, an arc-shaped groove is formed on the side wall of the second through hole, and an arc-shaped groove is formed on the side wall of the spiral plug, and the arc-shaped gas channel is formed between the arc-shaped groove on the side wall of the spiral plug and the arc-shaped groove on the side wall of the second through hole.

[0015] Optionally, the spiral plug includes a first structure and a second structure, the first structure is arranged around the second structure, the outer wall of the second structure is provided with an arc groove, and the inner wall of the first structure is provided with an arc groove, and when the first structure and the second structure are combined, the arc-shaped gas channel is formed between the arc groove of the first structure and the arc groove of the second structure.

[0016] Optionally, the arc-shaped groove is a groove extending in a spiral shape.

[0017] Optionally, the bottom surface of the screw plug is flush with the bottom surface of the dielectric layer;

[0018] Alternatively, a bottom surface of the screw plug protrudes from a bottom surface of the dielectric layer.

[0019] Optionally, a gas groove is formed on the top surface of the dielectric layer, and a top opening of the arc-shaped gas channel is connected to the gas groove.

[0020] Optionally, the top surface of the screw plug is flush with the bottom surface of the gas groove;

[0021] Alternatively, the top surface of the screw plug protrudes from the bottom surface of the gas groove.

[0022] Optionally, a porous plug is provided in the first through hole.

[0023] Optionally, there is a gap between the bottom surface of the screw plug and the top surface of the porous plug.

[0024] Optionally, the channel width of the arc-shaped gas channel is less than or equal to 1 mm.

[0025] Optionally, the channel width of the arc-shaped gas channel is 0.5% to 10% of the aperture of the second through hole.

[0026] Optionally, the area of ​​the top contour of the screw plug is greater than or equal to the area of ​​the bottom contour thereof.

[0027] Optionally, the dielectric layer and the base are connected via an adhesive layer.

[0028] Optionally, the screw plug and the dielectric layer are fixed by sintering or bonding.

[0029] Optionally, the screw plug is made of insulating material.

[0030] Optionally, the screw plug is made of ceramic material or polymer material.

[0031] Optionally, the dielectric layer is made of ceramic material.

[0032] Optionally, a plasma processing device comprises:

[0033] Vacuum reaction chamber;

[0034] The aforementioned lower electrode assembly is arranged in the vacuum reaction chamber.

[0035] Optionally, also include:

[0036] The upper electrode assembly is arranged opposite to the lower electrode assembly, and the upper electrode assembly comprises a gas spray plate, in which a gas supply channel is provided, and the gas spray plate is connected to a gas supply device.

[0037] Optionally, also include:

[0038] A radio frequency power supply is used to provide radio frequency energy to the vacuum reaction chamber.

[0039] Optionally, the lower electrode assembly includes a base having a first through hole and a dielectric layer having a second through hole, the first through hole is connected to the second through hole, and the first through hole is connected to a cooling gas source.

[0040] Compared with the prior art, the utility model has the following advantages:

[0041] In a lower electrode assembly and a plasma processing device thereof of the utility model, a spiral plug is arranged in the second through hole of the dielectric layer of the lower electrode assembly, and the spiral plug is used to lengthen the travel path of the gas in the second through hole, thereby effectively increasing the gas discharge path. At the same time, the arc-shaped gas channel increases the collision probability of charged particles with the side wall of the gas channel, thereby increasing the probability of charged particles being extinguished by collision, which helps to avoid through hole breakdown or arc ignition in the dielectric layer, thereby ensuring the stability of the environment in the cavity.

[0042] Furthermore, the arc-shaped gas channel in the second through hole of the dielectric layer is a gas channel extending in a spiral shape. The arc-shaped gas channel enables the gas to be transported in a spiral air intake manner at the second through hole, further increasing the gas travel path. At the same time, the gas channel with a spiral maze structure can further increase the collision probability between the charged particles and the side walls of the gas channel, thereby increasing the probability of the charged particles being extinguished by collision, which can greatly reduce the breakdown of the inner wall of the through hole, and help to ensure the service life of the electrostatic suction cup and the stability of the environment in the cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of a plasma processing device of the utility model;

[0044] Figure 2 Schematic diagram of Paschen curves for various gases;

[0045] Figure 3 It is a partially enlarged schematic diagram of an existing lower electrode assembly;

[0046] Figure 4 for Figure 3 Schematic diagram of the discharge path of the lower electrode assembly;

[0047] Figure 5 It is a partially enlarged schematic diagram of a lower electrode assembly of the utility model;

[0048] Figure 6 for Figure 5 Schematic diagram of the discharge path of the lower electrode assembly;

[0049] Figure 7 It is a three-dimensional structural schematic diagram of a screw plug of the utility model;

[0050] Figure 8 This is a structural schematic diagram of a screw plug of the utility model;

[0051] Fig. 9 for Figure 8 A bottom view of the screw plug in FIG.

[0052] Fig.10 It is a partial enlarged schematic diagram of another lower electrode assembly of the utility model;

[0053] Fig.11 It is a partially enlarged schematic diagram of another lower electrode assembly of the utility model. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0055] It should be noted that, in this article, the terms "include", "comprises", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "includes..." or "comprising..." do not exclude the existence of other elements in the process, method, article or terminal device including the elements.

[0056] It should be noted that the drawings are all in very simplified form and use inaccurate ratios, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present utility model.

[0057] like Figure 1As shown, it is a schematic diagram of a plasma processing device of the utility model, and the plasma processing device comprises: a vacuum reaction chamber 100, which is surrounded by a reaction chamber body and a chamber end cover 101, and the reaction chamber body is usually made of metal material, and comprises a chamber side wall 102 and a chamber bottom wall 103. A wafer transfer port 104 is provided on the chamber side wall 102, and the wafer transfer port 104 is used to realize the transfer of wafer W between the inside and outside of the vacuum reaction chamber 100. The vacuum reaction chamber 100 comprises a lower electrode assembly 110, which is arranged at the bottom of the vacuum reaction chamber 100, and the lower electrode assembly 110 comprises an electrostatic chuck, and the electrostatic chuck comprises a base 111 and a dielectric layer 112 arranged on the base 111, and the top surface of the dielectric layer 112 is used to carry the wafer W, and the wafer W to be processed introduced into the vacuum reaction chamber 100 through the wafer transfer port 104 is placed on the top surface of the dielectric layer 112. Furthermore, the vacuum reaction chamber 100 further includes an upper electrode assembly 120 disposed opposite to the lower electrode assembly 110, and the space between the upper electrode assembly 120 and the lower electrode assembly 110 is a processing area for processing the surface of the wafer W. The upper electrode assembly 120 includes a gas spray plate 121, and a plurality of gas supply channels 122 are provided in the gas spray plate 121. The gas spray plate 121 is connected to a gas supply device 130, and the process gas in the gas supply device 130 enters the vacuum reaction chamber 100 through the gas supply channel 122 of the gas spray plate 121.

[0058] At least one RF power supply 140 applies RF energy to the lower electrode assembly 110 through a matching network 141 to dissociate the process gas transported into the chamber through the gas spray plate 121 into plasma, thereby creating a plasma environment between the upper electrode assembly 120 and the lower electrode assembly 110 for etching. The plasma environment contains a large number of active particles such as electrons, ions, excited atoms, molecules and free radicals. The above-mentioned active particles can undergo various physical and / or chemical reactions with the surface of the wafer W to be processed, so that the morphology of the wafer W to be processed changes, thereby completing the processing of the wafer W to be processed.

[0059] In order to further optimize the processing effect of the wafer W, a through hole connected to the gas source 150 is usually opened on the electrostatic chuck to transport various types of application gases. During the process, the application gas in the gas source 150 is transported to the back side of the wafer W or the cavity through the through hole of the electrostatic chuck. For example, in actual applications, in order to prevent the wafer W from overheating during the plasma treatment process, cooling gas such as nitrogen is often used to remove the heat from the wafer W. Specifically, Figure 1As shown, a first through hole 1111 is provided on the base 111 of the electrostatic chuck, and the first through hole 1111 is connected to the cooling gas source 150. A second through hole 1121 is provided on the dielectric layer 112, and the second through hole 1121 is connected to the first through hole 1111. The cooling gas in the cooling gas source 150 contacts the back of the wafer W through the first through hole 1111 and the second through hole 1121 to take away the heat on the wafer W. However, in the actual reaction process, the vacuum reaction chamber 100 is usually in a high-power use environment, and the electrostatic chuck tends to be subjected to a large partial pressure. The greater the partial pressure, the easier it is for the gas in the through hole of the electrostatic chuck to be ionized under the action of the partial pressure, thereby causing the inner wall of the through hole to be broken down. In severe cases, it may also cause problems such as arc discharge of the electrostatic chuck, especially in the through hole area close to the back of the wafer W, where gas dissociation is more likely to occur and break through the inner wall of the through hole, thereby generating impurity particles in the through hole, and finally contaminating the wafer W.

[0060] Based on this problem, the industry usually starts with the Paschen's law of cooling gas to improve it. Figure 2 As shown in the figure, it is a Paschen curve that describes the relationship between the breakdown voltage of various gases and the gas pressure and electrode distance. It studies the voltage required to start a discharge or arc between two electrodes in a gas environment, that is, the breakdown voltage of various gases between the parallel plates of the electrodes changes with the change of gas pressure and gap distance. Paschen's law shows that: when the gap length between the two electrodes remains unchanged, the arc voltage required to cross the gap will decrease as the pressure in the gap increases within a certain range, and then when the pressure in the gap continues to increase, the arc voltage required to cross the gap will increase. Under constant pressure, as the gap size decreases, the voltage required to cause an arc will also decrease, but when it decreases to the minimum value, as the gap further decreases, the voltage required to generate an arc begins to rise. Taking into account the needs of the process, the power (voltage) needs to be continuously increased during the reaction process to meet the etching rate, and at the same time, a certain helium pressure must be maintained to ensure that the wafer W does not overheat. Therefore, a more effective way is to reduce the diameter (gap) of the helium hole. As Figure 3 As shown in the figure, a commonly used lower electrode assembly 210 is provided with a helium pore structure 211 in the dielectric layer of the electrostatic chuck of the lower electrode assembly 210. However, as the power and helium pressure continue to increase, this is a game between power / helium pressure and the diameter of the helium pore structure 211. Due to the limitation of processing capacity, the pore area will eventually be broken down and an arc will be formed. Figure 4 The discharge path at the helium pore structure 211 is shown ( Figure 4 As shown in the schematic diagram of the curved arrow in FIG. 2 , under a certain power and helium pressure, discharge will occur from the opening of the helium pore structure 211 to the metal base.

[0061] Based on the above, in order to avoid discharge from the opening of the helium pore structure 211 to the metal base, in addition to changing the diameter of the helium pore structure 211, the utility model provides another effective solution. In the utility model, the existing difficult-to-process pore method is abandoned, and a screw plug 113 is set in the second through hole 1121 of the dielectric layer 112 (see Figure 5 ), a curved gas channel 114 is provided in the second through hole 1121 by means of the screw plug 113, and the cooling gas of the cooling gas source 150 is transported to the back side of the wafer W through the curved gas channel 114. This structure increases the length of the gas discharge path in the second through hole 1121, and at the same time, the curved gas channel 114 increases the collision probability of the charged particles with the side wall of the curved gas channel 114. Even if a small amount of charged particles is generated, the probability of the charged particles extinguishing by collision is increased, which can greatly reduce the breakdown of the inner wall of the through hole, especially the area close to the back side of the wafer W, and helps to ensure the service life of the electrostatic chuck and the stability of the environment in the chamber.

[0062] Specifically, Figures 5 to 7 As shown, in the present invention, a screw plug 113 is provided in the second through hole 1121 of the dielectric layer 112. Inside the screw plug 113, and / or between at least part of the side wall of the screw plug 113 and the side wall of the second through hole 1121, there is an arc-shaped gas channel 114. The arc-shaped gas channel 114 has an air inlet connected to the first through hole 1111, and an air outlet directly connected to the top space of the dielectric layer 112. The cooling gas of the cooling gas source 150 is transported through the arc-shaped gas channel 114 at the second through hole 1121 and then reaches the back of the wafer W to cool the wafer W. As can be seen from the above, the screw plug 113 makes the second through hole 1121 of the dielectric layer 112 have an arc-shaped gas channel 114. The arc-shaped gas channel 114 makes the travel path of the cooling gas in the second through hole 1121 longer, thereby increasing the gas discharge path ( Figure 6 At the same time, the arc-shaped gas channel 114 increases the probability of charged particles colliding with the sidewall of the arc-shaped gas channel 114, thereby increasing the probability of charged particles extinguishing by collision, which helps to avoid through-hole breakdown or arc ignition in the dielectric layer 112, thereby ensuring the stability of the environment in the cavity. On the other hand, the second through hole 1121 has only one arc-shaped gas channel 114. Compared with the structure in which the second through hole 1121 has multiple interconnected channels (porous structure), the utility model can avoid mutual interference between the gas states of different channels.

[0063] In this embodiment, the arc-shaped gas channel 114 is a gas channel extending in a spiral shape from top to bottom. The arc-shaped gas channel 114 allows the cooling gas to be transported to the back side of the wafer W in a spiral air intake manner at the dielectric layer 112, further effectively increasing the gas travel path of the cooling gas, while also greatly increasing the theoretical discharge voltage. On the other hand, the arc-shaped gas channel 114 extending in a spiral shape also increases the collision and extinguishing probability of charged particles in the region, thereby avoiding the second through hole 1121 of the dielectric layer 112 from being punctured or arc ignition from occurring.

[0064] Furthermore, in this embodiment, the side wall of the screw plug 113 is provided with a spirally extending arc groove 1131 (see Figure 7 ), the side wall of the second through hole 1121 is an arc-shaped planar structure, and a spirally extending arc-shaped gas channel 114 is formed between the arc-shaped groove 1131 on the side wall of the spiral plug 113 and the side wall of the second through hole 1121. This structure reduces the processing difficulty of the second through hole 1121 of the dielectric layer 112, and this structure is also conducive to the assembly of the spiral plug 113 and the dielectric layer 112.

[0065] Of course, the arc-shaped gas channel 114 is not limited to being formed in the above-mentioned manner, and can also be formed in any other manner as long as it can have the corresponding functional effect, and the present invention does not impose any limitation on this. For example, in another embodiment, the side wall of the spiral plug 113 and the side wall of the second through hole 1121 are both processed with a spirally extending arc groove 1131, and the pitch and thread type of the arc groove 1131 of the two are the same. The spiral plug 113 is assembled in the second through hole 1121 of the dielectric layer 112, and a spirally extending arc gas channel 114 can be formed between the arc groove 1131 on the side wall of the spiral plug 113 and the arc groove on the side wall of the second through hole 1121. In this embodiment, by providing the arc groove 1131 structure on the side wall of the spiral plug 113 and the side wall of the second channel, the processing difficulty of the side wall of the spiral plug 113 is reduced, the spiral plug 113 is easy to machine, and the channel width of the arc gas channel 114 is controllable in processing, which is conducive to processing a small-sized spiral hole, thereby forming a small-sized arc gas channel 114. For example, in another embodiment, the spiral plug 113 includes a first structure and a second structure, the first structure is arranged around the second structure, and the first structure can be regarded as a ring structure, the second structure is a columnar structure, the outer side wall of the second structure is provided with an arc groove, the inner side wall of the first structure is provided with an arc groove, and when the first structure and the second structure are combined, the arc-shaped gas channel 114 is formed between the arc groove of the first structure and the arc groove of the second structure. Optionally, the arc groove is a groove extending in a spiral shape. As described above, this structure makes the channel width of the arc-shaped gas channel 114 controllable in processing, which is conducive to processing a small-sized spiral hole, thereby forming a small-sized arc-shaped gas channel 114.

[0066] On the other hand, the arc-shaped gas channel 114 is not limited to the above-mentioned one-segment channel structure. Based on actual processing requirements and process conditions, the arc-shaped gas channel 114 can also be composed of a plurality of channel sections, that is, it is a segmented channel. For example, in one embodiment, the spiral plug 113 includes a plurality of spiral blocks arranged from top to bottom, each of which is provided with an arc-shaped sub-channel running through the top and bottom thereof, and the arc-shaped sub-channels in each adjacent spiral block are interconnected to form the arc-shaped gas channel 114 together. In this embodiment, the arc-shaped gas channel 114 inside the spiral plug 113 is formed by combining the arc-shaped sub-channels of a plurality of segmented spiral blocks, thereby avoiding processing of the side wall of the second through hole 1121 of the dielectric layer 112, and reducing the processing difficulty. Of course, the side wall of the second through hole 1121 can also be used to form a segmented arc-shaped gas channel 114. For example, in another embodiment, the arc-shaped gas channel 114 includes a first gas channel and a second gas channel. The screw plug 113 is provided with a through hole to form the first gas channel. The second gas channel is formed between the side wall of the screw plug 113 and the side wall of the second through hole 1121. The first gas channel is connected to the second gas channel to form the arc-shaped gas channel 114. In practical applications, a suitable structural type can be selected for preparation and processing according to processing conditions and requirements, and the present invention does not limit this.

[0067] As discussed above, within a certain range, the smaller the channel width of the arc-shaped gas channel 114, the greater the voltage that the cooling gas can withstand without breakdown discharge (the situation on the left side of the lowest point of the Paschen curve). Optionally, the channel width of the arc-shaped gas channel 114 is less than or equal to 1 mm. On the other hand, optionally, the channel width of the arc-shaped gas channel 114 is 0.5% to 10% of the aperture of the second through hole 1121. Based on the above, the channel width of the arc-shaped gas channel 114 is much smaller than the aperture of the existing second through hole 1121. When the cooling gas supply pressure remains unchanged, the cooling gas pressure in the arc-shaped gas channel 114 is much smaller than the gas pressure in the existing second through hole 1121 (without the screw plug 113), thereby adjusting the product Pd of the inter-electrode distance d and the gas pressure P to the left of the lowest point of the Paschen curve, thereby significantly increasing the breakdown voltage that the cooling gas can withstand, and avoiding the cooling gas from breaking through the inner wall of the pore due to dissociation. Therefore, the arc-shaped gas channel 114 not only ensures gas circulation, but also helps to prevent through-hole breakdown and arc discharge, avoids damage to the electrostatic chuck, and also avoids the problem of foreign particles being generated in the through-hole.

[0068] like Figure 7As shown, in this embodiment, the overall outer contour of the screw plug 113 is cylindrical, and the area of ​​the top contour 1132 is equal to the area of ​​the bottom contour 1133, which is convenient for processing and preparation. Of course, the outer contour structure of the screw plug 113 is not limited to the above, and in other embodiments, it can also be other structures, which is not limited by the present invention. For example, Figure 8 and Fig. 9 As shown, in another embodiment, the overall outer contour of the screw plug 113 is truncated cone-shaped, the area of ​​its top contour 1132 is larger than the area of ​​its bottom contour 1133, and the shape structure of the second through hole 1121 is adapted to the overall outer contour of the screw plug 113 to reduce the difficulty of assembling the screw plug 113 and the dielectric layer 112. At the same time, the structure of the screw plug 113, which is larger at the top and smaller at the bottom, is also conducive to its stability after assembly. On the other hand, the outer surface area of ​​the side wall of the truncated cone-shaped screw plug 113 is larger, the length of the spiral arc groove 1131 opened on its outer surface is longer, and the gas travel path is longer, which can further avoid the dissociation or breakdown of the cooling gas.

[0069] Furthermore, the present invention does not impose any restrictions on the material for preparing the screw plug 113, and it can be prepared using any existing material. Optionally, the screw plug 113 is made of an insulating material, and the screw plug 113 made of an insulating material is filled in the second through hole 1121 of the dielectric layer 112, which increases the difficulty of electrical breakdown in this area. Further optionally, the screw plug 113 is made of a ceramic material or a polymer material. For example, in one embodiment, the screw plug 113 is made of a ceramic material, and the dielectric layer 112 is also made of a ceramic material. Compared with other materials, the assembly difficulty between the screw plug 113 made of a ceramic material and the dielectric layer 112 made of a ceramic material is smaller. Further, optionally, the screw plug 113 and the dielectric layer 112 are sintered and fixed to enhance the stability of the connection between the two. In actual assembly, after the screw plug 113 is pressed into or otherwise fitted into the second through hole 1121 of the dielectric layer 112, the connection between the two is sintered to sinter and fix the two. Of course, other existing methods can also be used to assemble and fix the two, and the utility model does not limit this. For example, in another embodiment, the screw plug 113 and the dielectric layer 112 are fixed by bonding, that is, there is an adhesive layer between the two to reduce the difficulty of assembly.

[0070] like Figure 5As shown, in this embodiment, the bottom surface of the screw plug 113 is flush with the bottom surface of the dielectric layer 112 to fill the space at the bottom of the second through hole 1121 of the dielectric layer 112, so as to prevent the voltage in this area from being too large due to the excessive space at the bottom of the dielectric layer 112, thereby preventing arc discharge from occurring. In actual assembly, after the screw plug 113 and the dielectric layer 112 are sintered and fixed, if there is a portion of the screw plug 113 protruding from the bottom surface of the dielectric layer 112, this portion of the screw plug 113 can be polished to make the bottom surface of the screw plug 113 flush with the bottom surface of the dielectric layer 112. This processing method is simple and easy to implement, and is conducive to the assembly of the screw plug 113 and the dielectric layer 112. Of course, the bottom surface of the screw plug 113 can also protrude from the bottom surface of the dielectric layer 112 (see Figure 5 The dotted area extending downward from the bottom of the screw plug 113, that is, along Figure 5 By extending in the direction of the arrow in FIG. 1 , the space at the bottom of the dielectric layer 112 can be further reduced, thereby reducing the voltage in the region and reducing the probability of arc discharge in the region.

[0071] On the other hand, in order to further enhance the cooling effect of the cooling gas on the wafer W, a gas groove 1122 is formed on the top surface of the dielectric layer 112 (see Fig.10 ), the top opening of the arc-shaped gas channel 114 is directly connected to the gas groove 1122. After the cooling gas passes through the first through hole 1111 of the base 111, it enters the arc-shaped gas channel 114 between the spiral plug 113 and the side wall of the second through hole 1121 through the air inlet, and then is transported in a spiral air intake manner, and directly enters the gas groove 1122 from the air outlet, and then diffuses in the gas groove 1122 to contact the back of the wafer W to take away the heat on the wafer W. Optionally, the gas groove 1122 on the surface of the dielectric layer 112 is one or more circles of interconnected arc-shaped grooves, and the top openings of each second through hole 1121 of the dielectric layer 112 are all connected to the arc-shaped grooves to increase the circulation range of the cooling gas and improve the utilization efficiency of the cooling gas. At the same time, the uniformity of the diffusion distribution of the cooling gas on the surface of the electrostatic chuck can also be achieved, which helps to ensure the uniformity of the cooling effect of the cooling gas and the temperature uniformity of the wafer W on the electrostatic chuck. It is understandable that the larger the width of the arc-shaped groove of the gas groove 1122 is, the more areas of the back side of the wafer W that the cooling gas contacts are, and the better the cooling effect is. For example, in one embodiment, the width of the arc-shaped groove of the gas groove 1122 is greater than the aperture of the second through hole 1121, so as to provide a larger diffusion space for the cooling gas.

[0072] like Fig.10As shown in FIG. 1 , in this embodiment, the top surface of the screw plug 113 is flush with the bottom surface of the gas groove 1122 to facilitate the assembly of the screw plug 113 in the dielectric layer 112. Of course, the top surface of the screw plug 113 may also protrude from the bottom surface of the gas groove 1122, that is, along the Fig.10 The screw plug 113 extends in the direction of the arrow in the figure to reduce the space between the screw plug 113 and the back side of the wafer W, that is, to reduce the distance d1 therebetween, thereby reducing the voltage in the back side space of the wafer W to avoid arc discharge due to excessive voltage in this area.

[0073] To further reduce the probability of through-hole breakdown and arc ignition in the electrostatic chuck, Fig.11 As shown, a porous plug 1112 may be provided in the first through hole 1111 of the base 111. The porous plug 1112 has multiple pores for gas circulation. The cooling gas flows through the pores of the porous plug 1112 to the air inlet of the spiral plug 113, and then the cooling gas is transported through the arc-shaped gas channel 114. The width of the pores in the porous plug 1112 is much smaller than the aperture of the first through hole 1111. When the cooling gas supply pressure is constant, the cooling gas pressure in the porous plug 1112 is significantly reduced, thereby significantly increasing the breakdown voltage that the cooling gas in this area can withstand, avoiding the breakdown phenomenon of the first through hole 1111 of the base 111, and helping to ensure the service life of the electrostatic chuck and the stability of the environment in the cavity.

[0074] like Fig.11 As shown, there is a gap d2 between the bottom surface of the screw plug 113 and the top surface of the porous plug 1112 to provide a certain assembly margin to prevent the dielectric layer 112 embedded with the screw plug 113 from causing damage to the base 111 during assembly, which helps to ensure the assembly effect of the electrostatic chuck. In actual assembly, the screw plug 113 is first embedded in the second through hole 1121 of the dielectric layer 112, and then the two are sintered to sinter and fix the two. Then, the dielectric layer 112 equipped with the screw plug 113 is assembled with the base 111, thereby realizing the assembly of the electrostatic chuck. Furthermore, the dielectric layer 112 and the base 111 are connected via an adhesive layer 115, and the adhesive layer 115 provides a certain gap between the bottom surface of the spiral plug 113 and the top surface of the porous plug 1112, thereby ensuring the tightness of the connection between the dielectric layer 112 and the base 111 and providing a certain assembly margin for the assembly of the dielectric layer 112 and the base 111.

[0075] It is understandable that, in actual applications, the through-hole breakdown or arc ignition phenomenon mentioned above is prone to occur not only in the through-holes for conveying cooling gas, but also in the through-holes for conveying other types of application gases opened in the lower electrode assembly 110. The same or similar problems also exist. Therefore, the spiral plug 113 of the utility model is not limited to use in through-holes for conveying cooling gas, it can also be used in through-holes for conveying other types of application gases, and can also achieve the same or similar effects.

[0076] In summary, in a lower electrode assembly 110 and a plasma processing device thereof of the utility model, the lower electrode assembly 110 is provided with a spiral plug 113 in the second through hole 1121 of the dielectric layer 112, and the spiral plug 113 is used to provide an arc-shaped gas channel 114 in the second through hole 1121 of the dielectric layer. The arc-shaped gas channel 114 lengthens the travel path of the gas in the second through hole 1121, thereby increasing the gas discharge path. Meanwhile, the arc-shaped gas channel 114 increases the collision probability between the charged particles and the side wall of the gas channel, thereby increasing the probability of the charged particles being extinguished by collision, thereby helping to avoid through hole breakdown or arc ignition in the dielectric layer 112, thereby ensuring the stability of the environment in the cavity.

[0077] Although the content of the utility model has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the utility model. After reading the above content, various modifications and substitutions of the utility model will be obvious to those skilled in the art. Therefore, the protection scope of the utility model should be limited by the attached claims.

Claims

1. A lower electrode assembly, characterized in that: Include: A base having a first through hole, wherein the first through hole is connected to a gas source; A dielectric layer is arranged on the base, and its top surface is used to support the wafer. The dielectric layer is provided with a second through hole, and a spiral plug is arranged in the second through hole. An arc-shaped gas channel is provided between the interior of the spiral plug and / or at least a part of the side wall of the spiral plug and the side wall of the second through hole, and the gas channel has an air inlet connected to the first through hole, and an air outlet connected to the top space of the dielectric layer.

2. The lower electrode assembly according to claim 1, characterized in that The arc-shaped gas passage is a gas passage extending in a spiral shape.

3. The lower electrode assembly according to claim 1 or 2, characterized in that: The spiral plug comprises a plurality of spiral blocks arranged from top to bottom, each of which is provided with an arcuate sub-channel running through the top and bottom thereof, and the arcuate sub-channels in adjacent spiral blocks are interconnected to form the arcuate gas channel.

4. The lower electrode assembly according to claim 1 or 2, characterized in that: The arc-shaped gas channel includes a first gas channel and a second gas channel. A through hole is opened on the screw plug to form the first gas channel. The second gas channel is formed between the side wall of the screw plug and the side wall of the second through hole. The first gas channel is connected to the second gas channel.

5. The lower electrode assembly according to claim 1, characterized in that: The side wall of the second through hole is an arc-shaped plane structure, and an arc-shaped groove is opened on the side wall of the screw plug. The arc-shaped gas channel is formed between the arc-shaped groove on the side wall of the screw plug and the side wall of the second through hole.

6. The lower electrode assembly according to claim 1, characterized in that The side wall of the second through hole is provided with an arc-shaped groove, and the side wall of the screw plug is provided with an arc-shaped groove, and the arc-shaped gas channel is formed between the arc-shaped groove on the side wall of the screw plug and the arc-shaped groove on the side wall of the second through hole.

7. The lower electrode assembly according to claim 1, characterized in that: The screw plug includes a first structure and a second structure, the first structure is arranged around the second structure, the outer wall of the second structure is provided with an arc groove, and the inner wall of the first structure is provided with an arc groove. When the first structure and the second structure are combined, the arc-shaped gas channel is formed between the arc groove of the first structure and the arc groove of the second structure.

8. The lower electrode assembly according to claim 5, 6 or 7, characterized in that: The arc-shaped groove is a groove extending in a spiral shape.

9. The lower electrode assembly according to claim 1, characterized in that: The bottom surface of the screw plug is flush with the bottom surface of the dielectric layer; Alternatively, a bottom surface of the screw plug protrudes from a bottom surface of the dielectric layer.

10. The lower electrode assembly according to claim 1, wherein: A gas groove is formed on the top surface of the dielectric layer, and a top opening of the arc-shaped gas channel is connected to the gas groove.

11. The lower electrode assembly according to claim 10, characterized in that The top surface of the screw plug is flush with the bottom surface of the gas groove; Alternatively, the top surface of the screw plug protrudes from the bottom surface of the gas groove.

12. The lower electrode assembly according to claim 1, wherein: A porous plug is disposed in the first through hole.

13. The lower electrode assembly according to claim 12, wherein: There is a gap between the bottom surface of the screw plug and the top surface of the porous plug.

14. The lower electrode assembly according to claim 1, wherein: The channel width of the arc-shaped gas channel is less than or equal to 1 mm.

15. The lower electrode assembly according to claim 1, wherein: The channel width of the arc-shaped gas channel is 0.5% to 10% of the aperture of the second through hole.

16. The lower electrode assembly according to claim 1, wherein: The area of ​​the top contour of the screw plug is greater than or equal to the area of ​​the bottom contour thereof.

17. The lower electrode assembly according to claim 1, wherein: The dielectric layer and the base are connected via an adhesive layer.

18. The lower electrode assembly according to claim 1, wherein: The screw plug and the dielectric layer are fixed by sintering or bonding.

19. The lower electrode assembly according to claim 1, wherein: The screw plug is made of insulating material.

20. The lower electrode assembly according to claim 1, wherein: The screw plug is made of ceramic material or polymer material.

21. The lower electrode assembly according to claim 1, wherein: The dielectric layer is made of ceramic material.

22. A plasma processing device, characterized in that: Include: Vacuum reaction chamber; The lower electrode assembly according to any one of claims 1 to 21 is arranged in the vacuum reaction chamber.

23. The plasma processing apparatus according to claim 22, wherein: Also includes: The upper electrode assembly is arranged opposite to the lower electrode assembly, and the upper electrode assembly comprises a gas spray plate, in which a gas supply channel is provided, and the gas spray plate is connected to a gas supply device.

24. The plasma processing apparatus according to claim 22, wherein: Also includes: A radio frequency power supply is used to provide radio frequency energy to the vacuum reaction chamber.

25. The plasma processing apparatus according to claim 22, wherein: The lower electrode assembly includes a base with a first through hole and a dielectric layer with a second through hole. The first through hole is connected to the second through hole, and the first through hole is connected to a cooling gas source.

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