Preparation method of built-in gas circuit of ceramic disc of electrostatic chuck

Abstract

The invention discloses a preparation method of a built-in gas circuit of a ceramic disc of an electrostatic chuck, and belongs to the technical field of electrostatic chucks. S2, processing a positioning hole, a via hole and a DC hole in the ceramic green sheet prepared in the above step through a machining center; s3, filling conductive metal slurry in the via hole, and printing a metal electrode layer, a first Via Pad layer and a second Via Pad layer on the surface of the ceramic green sheet in a screen printing manner; s4, laminating to form an upper ceramic green compact block and a lower ceramic green compact block; s5, performing gas path processing on the surface of the lower ceramic green compact block; s6, the upper ceramic green compact block and the lower ceramic green compact block subjected to gas circuit machining are stacked together in a positioning and stacking mode, and a complete gas circuit is formed; s7, degreasing and glue discharging are conducted on the upper ceramic green compact block and the lower ceramic green compact block, and the ceramic plate subjected to glue discharging is formed; s8, performing high-temperature sintering to obtain ceramic; and S9, the machining center machines the air outlet channel.

Description

Technical Field

[0001] The invention relates to the technical field of electrostatic chucks, and in particular to a method for preparing a built-in gas path of an electrostatic chuck ceramic disc. Background Art

[0002] In the prior art, generally speaking, an electrostatic chuck is formed by bonding a ceramic disk and a metal base. The ceramic disk has a built-in adsorption electrode, which adsorbs and clamps the wafer after power is applied. The base has a built-in cooling gas path (for example, He gas) and a water path. The cooling gas is introduced from the outside into the cooling gas path in the metal base, and then the cooling gas in the gas path is introduced into the surface of the ceramic disk through the air duct. The surface of the ceramic disk may have multiple cooling holes for cooling and temperature uniformity control during the wafer processing and manufacturing process.

[0003] The main defect of the prior art is that the gas circuit of this type of electrostatic chuck is built into the metal base, and the metal base is bonded to the ceramic disk, which has the defect of insufficient sealing. When the cooling gas is introduced into the ceramic disk through the gas circuit, there is a risk of cooling gas leakage. As the use time increases, the risk of gas leakage increases. At the same time, the cooling gas is first passed into the metal base and then introduced into the surface of the ceramic disk through the air duct, which may lead to poor cooling and temperature uniformity control during the wafer processing process. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a built-in gas path of an electrostatic chuck ceramic disk, so as to solve the problem raised by the background technology.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A method for preparing an electrostatic chuck ceramic disc with a built-in gas path, the preparation method comprising:

[0007] S1: The ceramic slurry is formed into a ceramic green sheet by a tape casting process. The thickness of the green sheet is 200-800um, and the thickness difference of a single sheet is within ±20um;

[0008] S2: machining the ceramic green sheets prepared in the above steps into positioning holes, conduction holes and DC holes through a machining center, which are used for fixing the positions of the ceramic green sheets when they are stacked, interconnecting and conducting different layers, and applying power to the ceramic green sheets with an external power source;

[0009] S3: filling the conductive metal paste into the via hole, and printing the metal electrode layer and the first via pad layer and the second via pad layer on the surface of the ceramic green sheet by screen printing;

[0010] S4: laminating the dielectric layer, the metal electrode layer, and the first via pad layer together by positioning lamination to form an upper ceramic green body block, and laminating the second via pad layer and the green body with DC holes processed together by positioning lamination to form a lower ceramic green body block;

[0011] S5: placing the lower ceramic green body block on the machining center platform, fixing it by adsorption through a vacuum suction cup, setting the processing program according to the gas path design drawing, processing the required width and depth of the gas path according to the requirements, and processing the gas path on the surface of the lower ceramic green body block;

[0012] S6: The upper ceramic green body block and the lower ceramic green body block after the gas path processing are stacked together by positioning and stacking to form a complete gas path. The stacking process of the upper ceramic green body block and the lower ceramic green body block needs to strictly control the pressure, time and temperature to prevent the upper ceramic green body block and the lower ceramic green body block from not being completely and tightly fitted or the gas path from collapsing.

[0013] S7: placing the tightly fitted upper ceramic green body block and the lower ceramic green body block in a debinding furnace, and performing debinding and debinding at a temperature of 300 to 550° C. in an air or nitrogen atmosphere, and removing organic matter from the tightly fitted upper ceramic green body block and the lower ceramic green body block to form a debinding ceramic disc;

[0014] S8: placing the debinding ceramic disc in a high-temperature sintering furnace, and sintering it at 1300-1800° C. into ceramic in a protective atmosphere of any one or more of N2, H2, and Ar;

[0015] S9: On the surface of the sintered ceramic disc with built-in gas path, an air channel is machined through a machining center to lead the cooling gas in the gas path to the surface of the ceramic disc.

[0016] Preferably, the ceramic material in the ceramic slurry in S1 is any one of Al2O3, AlN, SiC, and Si3N4.

[0017] Preferably, the metal paste for screen printing in step S3 may be any one of W, Mo, Mn, Ag, Pd, and Pt metals.

[0018] Preferably, in step S4, the pressure during the lamination of the upper ceramic green body block and the lower ceramic green body block is 100T to 500T, the lamination temperature is 30°C to 90°C, and the lamination time is 1min to 10min.

[0019] Preferably, in step S5, the gas path machining is performed by a 2-edge or 4-edge deep groove flat head milling cutter, wherein the cutter head material of the 2-edge or 4-edge deep groove flat head milling cutter is any one of cemented carbide, diamond, and ceramic.

[0020] Preferably, in step S6, when the upper ceramic green body block and the lower ceramic green body block are stacked, the stacking pressure is 20T to 200T, the stacking temperature is 30 to 80° C., and the stacking time is 1 to 10 min.

[0021] The above technical solution has the following beneficial effects:

[0022] 1. The present application processes the gas path on the surface of the ceramic green body and strictly controls the lamination process parameters by lamination, thereby ensuring that during the lamination process, the upper ceramic green body block and the lower ceramic green body block are tightly fitted and the internal gas path shape is complete, and the preparation method does not cause gas path collapse;

[0023] 2. The present application changes the gas path in the electrostatic chuck from the metal base in the prior art to the ceramic disk. After the gas path is built into the ceramic disk, it can effectively avoid the leakage of cooling gas in the process of leading the cooling gas from the metal base to the surface of the ceramic disk;

[0024] 3. The present application embeds the cooling gas path into the ceramic disk, which provides better wafer cooling and temperature reduction effects for the wafer during semiconductor process, while also providing better temperature uniformity control. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic cross-sectional view of the structure of the ceramic disc of the electrostatic chuck with built-in gas path of the present invention;

[0026] Figure 2 Design a structural diagram for the gas circuit;

[0027] Figure 3 This is a schematic diagram of the cross-sectional structure of a normal gas path;

[0028] Figure 4 It is a schematic diagram of the cross-sectional structure of gas path collapse. DETAILED DESCRIPTION

[0029] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Example 1

[0031] refer to Figure 1 , Figure 2 The preparation method of the electrostatic chuck ceramic disk with a built-in gas path includes:

[0032] S1: The ceramic slurry is formed into a ceramic green sheet by a tape casting process. The thickness of the green sheet is 200um to 800um, and the thickness difference of a single sheet is within ±20um. The ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, and Si3N4. That is, the preparation method is suitable for common ceramic materials to prepare an electrostatic chuck ceramic disc with a built-in gas path;

[0033] S2: machining the ceramic green sheets prepared in the above steps into positioning holes, conduction holes and DC holes 8 through a machining center, wherein the positioning holes are used to fix the positions of the ceramic green sheets when they are stacked, the conduction holes are used to interconnect different layers, and the DC holes 8 are used to apply power to the external power supply;

[0034] S3: Fill the via hole with a first conductive metal paste 9 and a second conductive metal paste 10, two second conductive metal pastes 10 are provided, and at the same time, a metal electrode layer 7, a first ViaPad layer 11, and a second Via Pad layer 12 are printed on the surface of the ceramic green sheet by screen printing. The Via Pad layer is the hole pad layer, and the metal paste printed by screen printing can be any one of W, Mo, Mn, Ag, Pd, and Pt metals;

[0035] S4: The dielectric layer 6, the metal electrode layer 7, and the first via pad layer 11 are stacked together by positioning and laminating to form an upper ceramic green body block, and the second via pad layer 12 and the green body with the DC hole 8 are stacked together by positioning and laminating to form a lower ceramic green body block, wherein the stacking pressure of the upper ceramic green body block and the lower ceramic green body block is 100T to 500T, the stacking temperature is 30°C to 90°C, and the stacking time is 1min to 10min;

[0036] S5: placing the lower ceramic green block on the machining center platform, fixing it by adsorption through a vacuum suction cup, setting the processing program according to the gas path design drawing, processing the required width and depth of the gas path 15 according to the requirements, and performing gas path processing 15 on the surface of the lower ceramic green block, wherein the gas path 15 is processed by a 2-edge or 4-edge deep groove flat head milling cutter, and the cutter head material of the 2-edge or 4-edge deep groove flat head milling cutter is any one of cemented carbide, diamond, and ceramic;

[0037] S6: The upper ceramic green body block and the lower ceramic green body block after the processing of the gas path 15 are stacked together by positioning and stacking to form a complete gas path. The stacking process of the upper ceramic green body block and the lower ceramic green body block needs to strictly control the pressure, time and temperature to prevent the upper ceramic green body block and the lower ceramic green body block from not being completely and tightly fitted or the gas path from collapsing. When the upper ceramic green body block and the lower ceramic green body block are stacked, the stacking pressure is 20T~200T, the stacking temperature is 30℃~80℃, and the stacking time is 1min~10min;

[0038] S7: placing the tightly fitted upper ceramic green body block and the lower ceramic green body block in a debinding furnace, and performing debinding and debinding at a temperature of 300° C. to 550° C. in an air or nitrogen atmosphere, and removing organic matter from the tightly fitted upper ceramic green body block and the lower ceramic green body block to form a debinding ceramic disc;

[0039] S8: placing the debinding ceramic disc in a high-temperature sintering furnace, and sintering the ceramic disc 13 at 1300° C. to 1800° C. in a protective atmosphere of any one or more of N2, H2, and Ar;

[0040] S9: On the surface of the ceramic disk 13 that has been sintered into porcelain and has a built-in gas path 15, a gas channel 14 is machined through a machining center so as to lead the cooling gas in the gas path 15 to the surface of the ceramic disk 13.

[0041] Example 2

[0042] refer to Figure 1 , Figure 2 The preparation method of the electrostatic chuck ceramic disk with a built-in gas path includes:

[0043] S1: The ceramic slurry is formed into a ceramic green sheet by a tape casting process. The thickness of the green sheet is 200um, and the thickness difference of a single sheet is within ±20um. The ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, and Si3N4. That is, the preparation method is suitable for common ceramic materials to prepare an electrostatic chuck ceramic disc with a built-in gas path;

[0044] S2: machining the ceramic green sheets prepared in the above steps into positioning holes, conduction holes and DC holes 8 through a machining center, wherein the positioning holes are used to fix the positions of the ceramic green sheets when they are stacked, the conduction holes are used to interconnect different layers, and the DC holes 8 are used to apply power to the external power supply;

[0045] S3: Fill the via hole with a first conductive metal paste 9 and a second conductive metal paste 10, two second conductive metal pastes 10 are provided, and at the same time, a metal electrode layer 7, a first ViaPad layer 11, and a second Via Pad layer 12 are printed on the surface of the ceramic green sheet by screen printing. The Via Pad layer is the hole pad layer, and the metal paste printed by screen printing can be any one of W, Mo, Mn, Ag, Pd, and Pt metals;

[0046] S4: The dielectric layer 6, the metal electrode layer 7, and the first via pad layer 11 are stacked together by positioning and laminating to form an upper ceramic green body block, and the second via pad layer 12 and the green body with the DC hole 8 are stacked together by positioning and laminating to form a lower ceramic green body block, wherein the stacking pressure of the upper ceramic green body block and the lower ceramic green body block is 100T, the stacking temperature is 30°C, and the stacking time is 1min;

[0047] S5: placing the lower ceramic green block on the machining center platform, fixing it by adsorption through a vacuum suction cup, setting the processing program according to the gas path design drawing, processing the required width and depth of the gas path 15 according to the requirements, and performing gas path processing 15 on the surface of the lower ceramic green block, wherein the gas path 15 is processed by a 2-edge or 4-edge deep groove flat head milling cutter, and the cutter head material of the 2-edge or 4-edge deep groove flat head milling cutter is any one of cemented carbide, diamond, and ceramic;

[0048] S6: The upper ceramic green body block and the lower ceramic green body block after the processing of the gas path 15 are stacked together by positioning and stacking to form a complete gas path. The stacking process of the upper ceramic green body block and the lower ceramic green body block needs to strictly control the pressure, time and temperature to prevent the upper ceramic green body block and the lower ceramic green body block from not being completely and tightly fitted or the gas path from collapsing. When the upper ceramic green body block and the lower ceramic green body block are stacked, the stacking pressure is 20T, the stacking temperature is 30°C, and the stacking time is 1min.

[0049] S7: placing the tightly fitted upper ceramic green body block and the lower ceramic green body block in a debinding furnace, and performing debinding and debinding at a temperature of 300° C. in an air or nitrogen atmosphere, and removing organic matter from the tightly fitted upper ceramic green body block and the lower ceramic green body block to form a debinding ceramic disc;

[0050] S8: placing the debinding ceramic disc in a high-temperature sintering furnace, and sintering it at 1300° C. in a protective atmosphere of any one or more of N2, H2, and Ar to form a ceramic disc 13;

[0051] S9: On the surface of the sintered ceramic disk 13 with the built-in gas path 15 , a gas channel 14 is machined through a machining center so as to lead the cooling gas in the gas path 15 to the surface of the ceramic disk 13 .

[0052] Example 3

[0053] refer to Figure 1 , Figure 2 The preparation method of the electrostatic chuck ceramic disk with a built-in gas path includes:

[0054] S1: The ceramic slurry is formed into a ceramic green sheet by a tape casting process. The thickness of the green sheet is 800um, and the thickness difference of a single sheet is within ±20um. The ceramic material in the ceramic slurry is any one of Al2O3, AlN, SiC, and Si3N4. That is, the preparation method is suitable for common ceramic materials to prepare an electrostatic chuck ceramic disc with a built-in gas path;

[0055] S2: machining the ceramic green sheets prepared in the above steps into positioning holes, conduction holes and DC holes 8 through a machining center, wherein the positioning holes are used to fix the positions of the ceramic green sheets when they are stacked, the conduction holes are used to interconnect different layers, and the DC holes 8 are used to apply power to the external power supply;

[0056] S3: Fill the via hole with the first conductive metal paste 9 and the second conductive metal paste 10, and print the metal electrode layer 7, the first via pad layer 11, and the second via pad layer 12 on the surface of the ceramic green sheet by screen printing. The via pad layer is the hole pad layer, and the metal paste for screen printing can be any one of W, Mo, Mn, Ag, Pd, and Pt metals;

[0057] S4: The dielectric layer 6, the metal electrode layer 7, and the first via pad layer 11 are stacked together by positioning lamination to form an upper ceramic green body block, and the second via pad layer 12 and the green body with DC holes 8 are stacked together by positioning lamination to form a lower ceramic green body block, wherein the stacking pressure of the upper ceramic green body block and the lower ceramic green body block is 500T, the stacking temperature is 90°C, and the stacking time is 10min;

[0058] S5: placing the lower ceramic green block on the machining center platform, fixing it by adsorption through a vacuum suction cup, setting the processing program according to the gas path design drawing, processing the required width and depth of the gas path 15 according to the requirements, and performing gas path processing 15 on the surface of the lower ceramic green block, wherein the gas path 15 is processed by a 2-edge or 4-edge deep groove flat head milling cutter, and the cutter head material of the 2-edge or 4-edge deep groove flat head milling cutter is any one of cemented carbide, diamond, and ceramic;

[0059] S6: The upper ceramic green body block and the lower ceramic green body block after the processing of the gas path 15 are stacked together by positioning and stacking to form a complete gas path. The stacking process of the upper ceramic green body block and the lower ceramic green body block needs to strictly control the pressure, time and temperature to prevent the upper ceramic green body block and the lower ceramic green body block from not being completely and tightly fitted or the gas path from collapsing. When the upper ceramic green body block and the lower ceramic green body block are stacked, the stacking pressure is 200T, the stacking temperature is 80°C, and the stacking time is 10min.

[0060] S7: placing the tightly fitted upper ceramic green body block and the lower ceramic green body block in a debinding furnace, and performing debinding and debinding at a temperature of 550° C. in an air or nitrogen atmosphere, and removing organic matter from the tightly fitted upper ceramic green body block and the lower ceramic green body block to form a debinding ceramic disc;

[0061] S8: placing the debinding ceramic disc in a high-temperature sintering furnace, and sintering it at 1800° C. in a protective atmosphere of any one or more of N2, H2, and Ar to form a ceramic disc 13;

[0062] S9: On the surface of the ceramic disk 13 that has been sintered into porcelain and has a built-in gas path 15, a gas channel 14 is machined through a machining center so as to lead the cooling gas in the gas path 15 to the surface of the ceramic disk 13.

[0063] Example 4

[0064] In order to study the influence of the lamination parameters of the upper ceramic green body block and the lower ceramic green body block on the bonding effect and gas path condition of the two, different lamination pressures, lamination temperatures and lamination times are set. The specific parameter selection, bonding effect and gas path shape are shown in Table 1:

[0065] Table 1:

[0066]

[0067]

[0068] For comparison, the lamination pressure was set to 50T. For example, under condition 1, incomplete lamination occurred. The other conditions and results are shown in Table 1.

[0069] The present application uses a ceramic green sheet formed by a casting process, and the ceramic green sheet is stacked to a lower ceramic green block with a required thickness by positioning and stacking. The lower ceramic green block is fixedly placed on a machining center platform, and a flat-head milling cutter is used. Figure 2 ,according to Figure 2 Set the machining program according to the gas path design drawing in the Figure 2In the figure, the lower ceramic green body block 17 is provided with an air path 5, wherein the design drawing can be set as required, and the air path 15 is processed on the surface of the lower ceramic green body block to the required depth and width; the upper ceramic green body block with the required composite thickness is manufactured according to the same positioning and laminating method; the upper ceramic green body block is positioned and stacked on the lower ceramic green body block with the air groove processed on the laminating machine platform, and the required temperature, time and pressure are set, and the upper ceramic green body block and the lower ceramic green body block are tightly fitted together by laminating. This process requires strict control of the set parameters, otherwise there will be problems such as stratification caused by insufficient pressure or airway collapse caused by excessive pressure, etc., refer to Figure 3 and Figure 4 , Figure 3 The middle ceramic plate 1 is provided with an airway hole 2, and the upper side wall of the airway hole 2 has a layer 16, which means that the pressure is insufficient and the two are not compacted. Figure 4 The ceramic plate 1 includes an airway hole 2, wherein the upper side wall 3, the left side wall 4 and the right side wall are all bent, that is, the airway collapse caused by excessive pressure; the tightly fitted ceramic block is placed in a debinding furnace for degreasing and debinding, and after debinding, it is sintered into porcelain at high temperature in a sintering furnace. After sintering, the ceramic plate with a built-in airway is processed and prepared.

[0070] The present application processes the gas path on the surface of the ceramic green body, and strictly controls the lamination process parameters by lamination, so as to ensure that the upper ceramic green body block and the lower ceramic green body block are tightly fitted and the internal gas path shape is complete during the lamination process, and the gas path collapse will not occur.

[0071] The present application changes the gas path in the electrostatic chuck from the metal base in the prior art to the ceramic disk. After the gas path is built into the ceramic disk, the leakage of cooling gas can be effectively avoided in the process of leading the cooling gas from the metal base to the surface of the ceramic disk.

[0072] The present application embeds a cooling gas path into a ceramic disk, thereby achieving better wafer cooling and temperature reduction effects on the wafer during semiconductor process steps, while also providing better temperature uniformity control.

[0073] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A method for preparing an electrostatic chuck ceramic disk with a built-in gas path, characterized in that: The preparation method comprises: S1: The ceramic slurry is formed into a ceramic green sheet by a tape casting process. The thickness of the green sheet is 200-800um, and the thickness difference of a single sheet is within ±20um; S2: machining the ceramic green sheets prepared in the above steps into positioning holes, conduction holes and DC holes through a machining center, which are used for fixing the positions of the ceramic green sheets when they are stacked, interconnecting and conducting different layers, and applying power to the ceramic green sheets with an external power source; S3: filling the conductive metal paste into the via hole, and printing the metal electrode layer and the first via pad layer and the second via pad layer on the surface of the ceramic green sheet by screen printing; S4: laminating the dielectric layer, the metal electrode layer, and the first via pad layer together by positioning lamination to form an upper ceramic green body block, and laminating the second via pad layer and the green body with DC holes processed together by positioning lamination to form a lower ceramic green body block; S5: placing the lower ceramic green body block on the machining center platform, fixing it by adsorption through a vacuum suction cup, setting the processing program according to the gas path design drawing, processing the required width and depth of the gas path according to the requirements, and processing the gas path on the surface of the lower ceramic green body block; S6: The upper ceramic green body block and the lower ceramic green body block after the gas path processing are stacked together by positioning and stacking to form a complete gas path. The stacking process of the upper ceramic green body block and the lower ceramic green body block needs to strictly control the pressure, time and temperature to prevent the upper ceramic green body block and the lower ceramic green body block from not being completely and tightly fitted or the gas path from collapsing. S7: placing the tightly fitted upper ceramic green body block and the lower ceramic green body block in a debinding furnace, and performing debinding and debinding at a temperature of 300 to 550° C. in an air or nitrogen atmosphere, and removing organic matter from the tightly fitted upper ceramic green body block and the lower ceramic green body block to form a debinding ceramic disc; S8: placing the debinding ceramic disc in a high-temperature sintering furnace, and sintering it at 1300-1800° C. into ceramic in a protective atmosphere of any one or more of N2, H2, and Ar; S9: On the surface of the sintered ceramic disc with built-in gas path, an air channel is machined through a machining center to lead the cooling gas in the gas path to the surface of the ceramic disc.

2. The method for preparing a built-in gas path of an electrostatic chuck ceramic disk according to claim 1, characterized in that: The ceramic material in the ceramic slurry in S1 is any one of Al2O3, AlN, SiC, and Si3N4.

3. The method for preparing a built-in gas path of an electrostatic chuck ceramic disk according to claim 1, characterized in that: The metal paste for screen printing in step S3 may be any one of W, Mo, Mn, Ag, Pd, and Pt metals.

4. The method for preparing a built-in gas path of an electrostatic chuck ceramic disk according to claim 1, characterized in that: In the step S4, the pressure of the upper ceramic green body block and the lower ceramic green body block during stacking is 100T to 500T, the stacking temperature is 30°C to 90°C, and the stacking time is 1min to 10min.

5. The method for preparing a built-in gas path of an electrostatic chuck ceramic disk according to claim 1, characterized in that: In the step S5, the gas path is processed by a 2-edge or 4-edge deep groove flat head milling cutter, wherein the cutter head material of the 2-edge or 4-edge deep groove flat head milling cutter is any one of cemented carbide, diamond, and ceramic.

6. The method for preparing a built-in gas path of an electrostatic chuck ceramic disk according to claim 1, characterized in that: In step S6, when the upper ceramic green body block and the lower ceramic green body block are stacked, the stacking pressure is 20T to 200T, the stacking temperature is 30 to 80° C., and the stacking time is 1 to 10 minutes.

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