Electrostatic chuck and manufacturing method thereof

Abstract

The invention relates to an electrostatic chuck and a manufacturing method thereof, and belongs to the technical field of electrostatic chucks. The electrostatic chuck comprises a base and a ceramic disc, a through first main air channel is formed in the center of the base, a non-through second main air channel is formed in the center of the first surface of the ceramic disc, electrodes and branch air channels extending in the radial direction and the circumferential direction of the ceramic disc are arranged in the ceramic disc, and a plurality of micropore sets are formed in the second surface of the ceramic disc. The first main air channel, the second main air channel, the branch air channels and the micropore sets are sequentially communicated. While the phenomenon of helium sparking or local breakdown in the air passage is avoided, the manufacturing cost and the assembling difficulty are remarkably reduced, and the problem that helium leaks from the eroded adhesive after long-time use is also avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrostatic chuck, in particular to an electrostatic chuck and a manufacturing method thereof. BACKGROUND

[0002] The electrostatic chuck (ESC) is widely used in the field of semiconductor manufacturing, and is commonly used for adsorbing and fixing wafers to be etched. The electrostatic chuck generally comprises a ceramic dielectric layer, an adsorption electrode inside the ceramic dielectric layer, an adhesive, a base, and the like. The electrostatic chuck generally has a helium gas passage, and the helium gas passes through the electrostatic chuck to reach the interlayer between the upper surface of the ceramic and the wafer, thereby playing a role in heat transfer and controlling the uniformity of the wafer temperature.

[0003] In the working condition of a high-power etching machine, the high voltage applied to the entire electrostatic chuck often causes discharge between the wafer and the ceramic disc, and may also cause ignition of helium gas in the gas passage, thereby damaging the wafer and the electrostatic chuck. The patent with publication number CN112970091B proposes a high-power electrostatic chuck with a feature of preventing helium hole ignition / arc, which solves the problem of discharge ignition by providing a dielectric multi-cavity plug in the helium pipeline. However, the preparation and processing of the dielectric multi-cavity plug and the installation of the isolation layer are relatively complex, and there are technical difficulties. In addition, during use, the adhesive between the ceramic disc and the base will be eroded by the plasma, significantly increasing the risk of helium gas leakage through the adhesive to the vacuum cavity of the machine. SUMMARY

[0004] To solve the problems of preparation difficulty and plasma erosion in the prior art, the present application proposes an electrostatic chuck and a manufacturing method thereof.

[0005] The above technical purposes of the present application are mainly solved by the following technical solutions: An electrostatic chuck, comprising a base and a ceramic disc, wherein the base is centrally provided with a first main gas passage, the first surface of the ceramic disc is centrally provided with a second main gas passage which is not through, the ceramic disc is internally provided with an electrode and a branch gas passage extending in the radial and circumferential directions of the ceramic disc, and the second surface of the ceramic disc is provided with a plurality of micro-hole groups, and the first main gas passage, the second main gas passage, the branch gas passage, and the micro-hole groups are sequentially communicated.

[0006] Preferably, the branch gas passage comprises a plurality of circumferentially extending first branch gas passages and a radially extending second branch gas passage, and the second branch gas passage is used to communicate the second main gas passage with all the first branch gas passages; all the second branch gas passages in the ceramic disc are collected into only one second branch gas passage, which is communicated with the aluminum base, thereby reducing the assembly difficulty.

[0007] Preferably, the cross section of the branch gas passage is circular, which avoids the influence of deformation of the ceramic disc in the process of hot pressing and is convenient for processing.

[0008] Preferably, the first and second main gas channels are not on the same axis with any of the micro-hole groups, which significantly reduces the risk of helium sparking or local breakdown.

[0009] Preferably, the base and the ceramic disc are connected by adhesive, which ensures the sealing between the two and prevents gas leakage.

[0010] Preferably, on the side of the base facing the ceramic disc, a separation band is provided around the port of the first main gas channel to prevent the adhesive from flowing into the first main gas channel and ensure the smoothness of the gas channel.

[0011] In another aspect, the present application also provides a manufacturing method of the electrostatic chuck described above, comprising the following steps: S1. Prepare three equal-sized disc-shaped ceramic green bodies as the first, second and third green bodies, process a plurality of circumferentially extending grooves on the single-sided surface of the first and second green bodies, process a through hole in the center of the first green body, process a blind hole with the same diameter as the through hole on the groove surface of the second green body, and process a radially extending groove on the groove surface of the first and second green bodies to connect the plurality of circumferentially extending grooves.

[0012] S2. Fill the grooves of the first and second green bodies with glue, and after the glue fills the grooves, dry it in an oven at 60-80°C until the glue solidifies. The solidified glue has the same "pressure-deformation" coefficient as the green body.

[0013] S3. Print conductive paste on one side surface of the third green body.

[0014] S4. Perform lamination and hot pressing of the first, second and third green bodies, with the groove surfaces of the first and second green bodies placed opposite each other, and the conductive paste coated surface of the third green body placed opposite the other surface of the second green body.

[0015] S5. Perform heating and glue removal on the three-layer green body after hot pressing.

[0016] S6. Perform sintering on the three-layer green body after glue removal to obtain a ceramic disc provided with an electrode, a branch gas channel and a second main gas channel.

[0017] S7. Thin the one side surface of the third green body of the ceramic disc, and process a micro-hole group on the thinned surface to make the micro-holes communicate with the branch gas channel inside the ceramic disc.

[0018] S8. Prepare a base provided with a first main gas channel in the center, install a separation band on the surface of the base and uniformly apply adhesive, and bond the base with the ceramic disc after processing the micro-hole group.

[0019] Preferably, the cross sections of the grooves processed on the first and second embryos are semicircular to ensure uniform stress in all directions of the grooves during hot pressing, thereby ensuring that the shape of the final gas channel is controllable.

[0020] Preferably, the grooves on the surfaces of the first and second embryos are processed by ultra-short pulse laser processing, which can process grooves with accurate dimensions without damaging the soft green body material.

[0021] Preferably, the circumferentially extending grooves on the surfaces of the first and second embryos are three annular grooves, which make the distribution of gas flow in the ceramic disc more uniform and improve the temperature uniformity and mechanical stability of the electrostatic chuck.

[0022] The present application only needs one main gas channel that penetrates the ceramic disc and the base. Since the helium gas channel of the ceramic disc is no longer directly opposite the aluminum base helium gas channel, the present application does not need to use a porous ceramic plug, thereby greatly reducing the manufacturing difficulty and cost and improving the product yield. In addition, since the main gas channel penetrates the middle of the adhesive, even if the adhesive is eroded after long-term use in the machine, the eroded part is still far away from the main gas channel, avoiding helium gas leakage through the adhesive to the outside and improving the service life. The helium gas outlet holes on the surface of the ceramic disc are no longer directly opposite the helium gas outlet holes on the top of the aluminum base, but are bent and collected into the middle main gas channel, significantly reducing the risk of helium gas sparking or local breakdown. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The cross-sectional schematic diagram of the electrostatic chuck of an embodiment of the present application; Figure 2 The green body embryo structure schematic diagram of an embodiment of the present application; Figure 3 The first and second embryo groove surface structure schematic diagram of an embodiment of the present application; Figure 4 The ceramic disc mature embryo surface micropore layout schematic diagram of an embodiment of the present application.

[0024] REFERENCE NUMERALS: 1-base, 2-ceramic disc, 3-adhesive, 4-isolation belt, 101-first main gas channel, 201-second main gas channel, 202-first branch gas channel, 203-second branch gas channel, 204-micropore group, 205-first embryo, 206-second embryo, 207-third embryo. DETAILED DESCRIPTION

[0025] To further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purposes, the specific embodiments, structures, features and effects according to the present application are described in detail below in combination with the drawings and preferred embodiments.

[0026] Embodiment 1 The embodiment of the present application provides a static chuck, referring to Figures 1-4 , comprising a base 1, a ceramic disc 2, an adhesive 3 and an isolation belt 4. The base 1 is provided with a first main air channel 101 in the center, and the main channel is a through hole penetrating through the two side surfaces of the base 1. The two ends of the first main air channel 101 are the outlet end and the inlet end respectively, and the isolation belt 4 is arranged around the outlet end of the main air channel on the side surface of the base 1. Except the isolation belt 4 and the internal region of the isolation belt 4, the adhesive 3 is uniformly arranged, and the ceramic disc 2 and the base 1 are bonded through the adhesive 3.

[0027] The two side surfaces of the ceramic disc 2 are a second surface and a first surface respectively, and the first surface is bonded with the base 1. The first surface is provided with a second main air channel 201 in the center, and the second surface is provided with a plurality of micro-hole groups 204. Each micro-hole group 204 comprises a plurality of micro-holes, and the ceramic disc 2 is internally provided with an adsorption electrode and a branch air channel. The first main air channel 101, the second main air channel 201, the branch air channel and the micro-holes are sequentially communicated to form a gas channel penetrating through the two sides of the static chuck. The adsorption electrode is closer to the first surface of the ceramic disc 2 than the branch air channel, and the adsorption electrode has a vacancy in the center for the second main air channel 201 to pass through, and can be designed as different electrode shapes. The gas channel penetrating through the two sides of the static chuck is a helium gas channel in the embodiment, and the helium gas passes through the ceramic disc 2 internally through the coiled branch air channel, thereby playing a role of heat transfer and temperature uniformity control of the adsorption target. Compared with the prior art in which the horizontal gas channel is arranged in the base, the branch air channel arranged in the ceramic disc 2 of the embodiment is closer to the adsorption target, and the temperature control effect is better.

[0028] The branch air channel comprises a plurality of annular first branch air channels 202 concentric with the ceramic disc 2 and a radial second branch air channel 203. The second branch air channel 203 is linear, extends from the second main air channel 201 in the center of the ceramic disc 2 to the outermost first branch air channel 202, and is used for connecting the second main air channel 201 and all the first branch air channels 202 to enable the gas to flow into the first branch air channel 202 along multiple paths. The micro-hole groups 204 on the second surface of the ceramic disc 2 are all arranged at positions corresponding to the first branch air channels 202, and the layout of the micro-hole groups 204 in the embodiment is as shown in Figure 4 It should be noted that the micro-hole groups 204 are not arranged at positions corresponding to the first main air channel 101 and the second main air channel 201, so as to avoid the occurrence of

[0029] Embodiment 2 The embodiment of the present application provides a manufacturing method of the static chuck, and the specific technical scheme comprises the following steps.

[0030] S1. Prepare three equal-sized circular disc-shaped ceramic green bodies, at this time the green bodies are green bodies, process a plurality of annular grooves with a semicircular cross-section on the single-sided surface of two of the first body 205 and the second body 206, each annular groove is concentrically arranged, the grooves processed on the first body 205 and the second body 206 are the same in shape and size, so that the groove sides of the first body 205 and the second body 206 can form a bronchial tube with a circular cross-section after being oppositely combined. A through hole is processed at the center of the first body 205, and a blind hole is processed at the center of the second body 206, the through hole and the blind hole are the same in diameter, and the through hole and the blind hole are combined to form a second main airway 201. A semicircular groove is processed along the radius from the through hole / blind hole on the surface of the green body to the outermost annular groove, and the through hole / blind hole and each layer of annular groove are connected. All the grooves are processed by ultrashort pulse laser processing, and in this embodiment, femtosecond laser processing is specifically used. The three green bodies after processing are as shown in FIGS. 1, 2 and 3. Figure 2 and Figure 3

[0031] S2. Place the first body 205 and the second body 206 with the groove faces upward, fill the glue into the groove, and the glue self-levels in the groove. After the glue fills the groove, it is dried in an oven at 60-80°C for more than 1 hour to ensure that the glue is solidified. The solidified glue has the same “pressure-deformation” coefficient as the green body. It should be noted that it is crucial to ensure that the “pressure-deformation” coefficient of the filled glue is equal to that of the green body, otherwise uneven shrinkage of the groove may occur during hot pressing, and even the separation of the upper and lower two layers of the green body.

[0032] S3. Print conductive paste on one side surface of the third body 207.

[0033] S4. Place the first body 205, the second body 206 and the third body 207 in turn from top to bottom, wherein the groove faces of the first body 205 and the second body 206 are oppositely placed, and each groove is aligned to form a bronchial tube. The third body 207 is placed with the conductive paste face upward. After stacking, plastic packaging is performed, and then the three-layer green body is subjected to a hot pressing process to ensure that the multi-layer green body is tightly attached and the density is improved. After hot pressing, the three-layer green body is preliminarily combined.

[0034] S5. The three-layer green body after hot pressing is sent to a glue removal furnace for high-temperature glue removal, and the temperature is 300-500°C. The glue filled in the bronchial tube between the first body 205 and the second body 206 is gasified and discharged from the top glue discharge hole of the stacked green body, thereby forming a stable internal passage.

[0035] S6. The green body after glue removal is transferred to a higher-temperature reducing atmosphere furnace for high-temperature sintering, and finally a ceramic disc green body containing an internal passage is obtained, and the conductive paste printed on the surface of the third body 207 is converted to a solid state as an adsorption electrode. ​

[0036] S7. The third embryo 207 of the ceramic disc embryo is thinned on one side, and then the micro-hole group 204 is processed by a CNC engraving machine or the like to make the micro-holes communicate with the air branch inside the ceramic disc 2, thereby constructing a gas passage that enters from the central air branch on one side and exits from the micro-holes on the other side. The diameter of the micro-holes is less than 1 mm.

[0037] S8. An aluminum base 1 with a first main air branch 101 is prepared, a separation belt 4 is arranged around the outlet of the first main air branch 101 of the aluminum base 1, the surface of the aluminum base 1 outside the separation belt 4 is uniformly coated with adhesive 3, the first main air branch 101 of the aluminum base 1 is opposite to the ceramic second main air branch 201, the ceramic disc 2 is bonded and assembled with the aluminum base 1, and an electrostatic chuck product is obtained.

[0038] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application still belong to the scope of the technical solution of the present application.

Claims

1. An electrostatic chuck, characterized in that: It includes a base and a ceramic disk, wherein a through first main airway is provided in the center of the base, a non-through second main airway is provided in the center of the first surface of the ceramic disk, electrodes and branch airways extending along the radial and circumferential directions of the ceramic disk are provided inside the ceramic disk, and a plurality of micropore groups are provided on the second surface of the ceramic disk, and the first main airway, the second main airway, the branch airway and the micropore groups are connected in sequence.

2. The electrostatic chuck according to claim 1, wherein The bronchial airway includes a plurality of circumferentially extending first bronchial airways and a radially extending second bronchial airway, wherein the second bronchial airway is used to connect the second main airway with all the first bronchial airways.

3. The electrostatic chuck according to claim 1, wherein The cross section of the bronchus is circular.

4. The electrostatic chuck according to claim 1, wherein: The first main air channel and the second main air channel are not on the same axis as any one of the microhole groups.

5. The electrostatic chuck according to claim 1, wherein The base and the ceramic plate are connected via adhesive.

6. The electrostatic chuck according to claim 1, wherein: An isolation zone is provided around the first main air channel port on the side of the base facing the ceramic disk.

7. A method for manufacturing the electrostatic chuck according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Prepare three equal-sized disc-shaped ceramic green bodies as the first, second, and third bodies, machine multiple circumferentially extending grooves on one side of the first and second bodies, machine a through hole in the center of the first body, machine a blind hole with the same diameter as the through hole on the groove surface of the second body, and machine radially extending grooves on the groove surfaces of the first and second bodies to connect the multiple circumferentially extending grooves; S2. Fill the grooves of the first and second embryos with colloid. After the grooves are filled with colloid, dry them in an oven at 60-80°C until the colloid solidifies. The solidified colloid has the same pressure-deformation coefficient as the green embryo. S3. Printing a conductive paste on one side of the surface of the third embryo body; S4. The first embryo, the second embryo and the third embryo are laminated and hot-pressed, the groove surfaces of the first embryo and the second embryo are placed opposite each other, and the conductive paste-coated surface of the third embryo is placed opposite the other surface of the second embryo; S5. Heating and debinding the three-layer embryo after hot pressing; S6. The three-layer embryo body after debinding is sintered to obtain a ceramic disc having electrodes, bronchial airways and a second main airway; S7. Thinning one side of the third embryonic body of the ceramic disc, and processing a micropore group on the thinned surface so that the micropores communicate with the bronchial duct inside the ceramic disc; S8. Prepare a base with the first main airway in the center. Install an isolation tape on the surface of the base and evenly apply adhesive. Bond the base to the ceramic disc with the micropores machined.

8. The method according to claim 7, characterized in that The cross sections of the grooves processed in the first embryonic body and the second embryonic body are both semicircular.

9. The method according to claim 7, characterized in that All grooves on the surfaces of the first embryo body and the second embryo body are processed by ultrashort pulse laser processing.

10. The method according to claim 7, characterized in that The circumferentially extending grooves on the surfaces of the first embryonic body and the second embryonic body are specifically three circles of annular grooves.

Images