Composite ceramic electrostatic chuck and method of manufacturing the same

Abstract

The application discloses a manufacturing method of a composite ceramic electrostatic chuck, and belongs to the technical field of ceramic manufacturing.The method comprises the following steps: step 1, providing a ceramic flow sheet, printing a metal electrode to obtain a first flow sheet; step 2, mixing high dielectric strength ceramic powder, an organic solvent, a dispersing agent, a binder and a plasticizer to prepare high dielectric strength flow slurry, wherein the high dielectric strength ceramic powder comprises any one of the following: tantalum pentoxide and hexagonal boron nitride; step 3, printing the high dielectric strength flow slurry at a gap to obtain a second flow sheet; and step 4, covering a ceramic flow sheet on the upper surface of the second flow sheet to perform laminated forming.The composite ceramic electrostatic chuck manufactured by the method can reduce the gap while ensuring that the ceramic flow sheet is not broken down under high voltage, can increase the adsorption area of the electrode and the wafer, and can improve the adsorption force of the wafer, so that the heat dissipation performance and the temperature uniformity of the wafer are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor manufacturing, and relates to an electrostatic chuck for wafer fixation, in particular to a composite ceramic electrostatic chuck and a manufacturing method thereof. BACKGROUND

[0002] An electrostatic chuck is a key device for fixing wafers during semiconductor manufacturing process, which uses electrostatic force or other electric force to attract wafers, and is crucial to ensure the high quality and consistency of semiconductor products. However, there are some technical challenges in existing alumina / aluminum nitride ceramic electrostatic chuck products.

[0003] The dielectric strength of alumina / aluminum nitride ceramic electrostatic chuck is usually around 20kV / mm, which is an important parameter for measuring the maximum electric field strength that a material can withstand without breakdown. In order to avoid the application of high voltage exceeding the dielectric strength of air, causing air ionization and resulting in undesirable discharge leading to equipment damage, a gap of about 3mm is usually maintained between the electrode and the outer edge of the ceramic. At the same time, in order to ensure that the ceramic will not be broken down and cause arcing accidents under the action of high voltage, a gap of about 3mm is also maintained between the electrodes and the edges of the pin hole and helium gas hole. Although this gap design can prevent arcing accidents, it also brings some limitations.

[0004] Because the electrode cannot cover the entire ceramic disc surface, the areas where these gaps are located cannot generate suction force during use, resulting in uneven local suction force on the wafer. This uneven suction force will affect the heat dissipation performance of these locations on the wafer, and further adversely affect the uniformity of the wafer temperature. In the semiconductor processing process, the uniformity of the wafer temperature is crucial to ensure the processing precision and product quality.

[0005] In order to improve the heat dissipation performance and temperature uniformity of the wafer, researchers are actively exploring ways to improve the performance of the wafer by improving the design of the electrostatic chuck. SUMMARY

[0006] The purpose of the present application is to reduce the gap by printing any one of high dielectric strength ceramic materials such as tantalum pentoxide (Ta2O5) and hexagonal boron nitride (BN) in the gap between the electrodes and the edges of the ceramic outer edge, pin hole and helium gas hole, while ensuring that the ceramic tape casting sheet is not broken down under high voltage, so that the local suction force on the wafer is more uniform, thereby improving its heat dissipation performance and temperature uniformity.

[0007] In order to achieve the above purpose, the present application provides a manufacturing method of a composite ceramic electrostatic chuck, which comprises:

[0008] Step 1, providing a ceramic flow sheet, reserving a center pin hole and helium holes, the center pin hole is located at the center of the ceramic flow sheet, the helium holes are uniformly distributed on the surface of the ceramic flow sheet, printing a metal electrode on the ceramic flow sheet using a silk screen, obtaining a first flow sheet, wherein the gap between the metal electrode and the center pin hole and the helium holes is 0.5mm-2.5mm, the gap between the metal electrode and the outer edge of the ceramic flow sheet is 0.5mm-2.5mm;

[0009] Step 2, mixing high dielectric strength ceramic powder, organic solvent, dispersant, binder and plasticizer to prepare high dielectric strength flow slurry, the high dielectric strength ceramic powder includes any one of tantalum pentoxide and hexagonal boron nitride;

[0010] Step 3, replacing the silk screen, printing the high dielectric strength flow slurry at the gap to obtain a second flow sheet;

[0011] Step 4, covering a ceramic flow sheet on the surface of the second flow sheet to form a laminated shape.

[0012] Optionally, the metal electrode includes a first electrode and a second electrode, wherein the second electrode is arranged outside the first electrode, there is a first gap between the first electrode and the center pin hole and the helium holes surrounded by the first electrode, there is a second gap between the outer edge of the first electrode and the inner edge of the second electrode, there is a third gap between the second electrode and the helium holes surrounded by the second electrode, there is a fourth gap between the outer edge of the second electrode and the outer edge of the ceramic flow sheet, the first gap, the second gap, the third gap and the fourth gap are all 0.5mm-2.5mm.

[0013] Optionally, in step 2, the high dielectric strength flow slurry is doped with a binding aid, the binding aid includes any one of aluminum oxide powder and aluminum nitride powder, the mass fraction of the binding aid in the high dielectric strength flow slurry is 0-5%.

[0014] Optionally, in step 2, the mass fraction of the high dielectric strength ceramic powder in the high dielectric strength flow slurry is 25%-50%, the purity of the high dielectric strength ceramic powder is 99%-100%, the particle size is 0.05μm-50μm, and the dielectric strength is greater than 40kV / mm.

[0015] Optionally, in step 2, the organic solvent includes one or more of anhydrous ethanol, isopropyl alcohol, acetone and toluene, and the mass fraction of the organic solvent in the high dielectric strength flow slurry is 40%-65%.

[0016] Optionally, in the step 2, the dispersant includes any one of castor oil phosphate, triethanolamine, polyacrylamide, and the mass fraction of the dispersant in the high dielectric strength casting slurry is 0.2%-3%.

[0017] Optionally, in the step 2, the binder includes any one of polyvinyl butyral, acrylic acid, and the mass fraction of the binder in the high dielectric strength casting slurry is 3%-10%.

[0018] Optionally, in the step 2, the plasticizer includes any one of butyl benzyl phthalate, butyl phthalate, dioctyl phthalate, and the mass fraction of the plasticizer in the high dielectric strength casting slurry is 3%-10%.

[0019] Optionally, after the step 4, the method further includes a degassing and / or sintering step.

[0020] The application also provides a composite ceramic electrostatic chuck obtained by the manufacturing method.

[0021] Compared with the prior art, the technical scheme of the application has at least the following beneficial effects:

[0022] The application prints any one of high dielectric strength ceramic materials of tantalum pentoxide and hexagonal boron nitride between the electrodes and the gaps between the electrodes and the outer edge of the ceramic, pin hole and He gas hole, and the gap can be reduced to 0.5mm-2.5mm under the condition that the ceramic casting sheet is not broken down when high voltage is ensured, and the adsorption area of the electrode and the wafer can be increased, and the adsorption force of the wafer can be improved, so that the heat dissipation performance and temperature uniformity of the wafer are effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A cross-sectional view of an alumina casting sheet prepared by the application.

[0024] Figure 2 A structure view of a first casting sheet prepared by the application.

[0025] Figure 3 A structure view of a second casting sheet prepared by the application; wherein the green area represents tantalum pentoxide casting slurry.

[0026] Figure 4 A cross-sectional view of a composite ceramic body prepared by the application.

[0027] IDENTIFICATION OF DRAWINGS

[0028] Pin hole 11

[0029] He gas hole 12

[0030] first electrode 21

[0031] second electrode 22

[0032] first gap 31

[0033] second gap 32

[0034] third gap 33

[0035] fourth gap 34

[0036] alumina tape 41

[0037] first tape 42

[0038] second tape 43

[0039] composite ceramic body 44. DETAILED DESCRIPTION

[0040] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0041] In the description of the present application, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0042] In the following examples, the experimental methods used are carried out according to the conventional or manufacturer's recommended conditions, unless otherwise specified.

[0043] As described in the background, the area where the electrode gap, pin hole and He gas hole edge gap are located cannot generate adsorption force in use, resulting in uneven local adsorption force of the wafer, which will adversely affect the heat dissipation performance and temperature uniformity of the wafer. In order to improve the heat dissipation performance and temperature uniformity of the wafer, the present application prints any one of high dielectric strength ceramic materials such as tantalum pentoxide and hexagonal boron nitride at the electrode gap, pin hole and He gas hole edge gap. Because of its high dielectric strength, it can reduce the gap while ensuring that the ceramic tape casting sheet is not broken down under high voltage, and at the same time can increase the adsorption area of the electrode and the wafer, so that the local adsorption force of the wafer is more uniform. Specifically, the present application provides a manufacturing method of a composite ceramic electrostatic chuck, which comprises:

[0044] Step 1, providing a ceramic tape casting sheet, reserving a pin hole and a helium gas hole, the pin hole is located at the center of the ceramic tape casting sheet, the helium gas holes are uniformly distributed on the surface of the ceramic tape casting sheet, printing a metal electrode on the ceramic tape casting sheet using a screen printing plate to obtain a first tape casting sheet, wherein the gap between the metal electrode and the pin hole and the helium gas hole is 0.5mm-2.5mm, and the gap between the metal electrode and the outer edge of the ceramic tape casting sheet is 0.5mm-2.5mm.

[0045] Wherein, the preparation of the ceramic tape casting sheet comprises the steps of preparing ceramic tape casting slurry and tape casting. The ceramic powder, organic solvent, dispersant, binder and plasticizer are mixed to prepare the ceramic tape casting slurry, and the ceramic tape casting slurry is poured into the slurry tank of the casting machine to form the ceramic tape casting sheet and dry.

[0046] In some embodiments, the ceramic tape casting sheet comprises any one of an alumina tape casting sheet and an aluminum nitride tape casting sheet.

[0047] Figure 1 The cross-sectional view of the alumina tape casting sheet prepared by the present application is shown in the figure. The positions of the pin hole 11 and the He gas hole 12 are reserved on the alumina tape casting sheet 41 (see Figure 2 ), the pin hole 11 is used for accurate transmission of the wafer, and the He hole 12 is used for passing in helium gas, which has good heat conduction performance and is used for gas flow on the back of the wafer to help adjust the temperature of the wafer.

[0048] Taking a bipolar electrode as an example, as Figure 2As shown, a metal electrode is printed on the alumina casting sheet 41 using a silk screen and dried to obtain a first casting sheet 42, the metal electrode comprising a first electrode 21 and a second electrode 22, the second electrode 22 surrounding the first electrode 21, a first gap 31 between the first electrode 21 and the pin hole 11 and the He gas hole 12 surrounded thereby, a second gap 32 between the outer edge of the first electrode 21 and the inner edge of the second electrode 22, a third gap 33 between the second electrode 22 and the He gas hole 12 surrounded thereby, and a fourth gap 34 between the outer edge of the second electrode 22 and the outer edge of the alumina casting sheet 41. The manufacturing method of the present application can reduce the gaps.

[0049] In step 2, high dielectric strength ceramic powder, organic solvent, dispersant, binder and plasticizer are mixed to prepare high dielectric strength casting slurry.

[0050] The high dielectric strength ceramic powder comprises any one of tantalum pentoxide and hexagonal boron nitride. To ensure optimal effect, the mass fraction of the high dielectric strength ceramic powder in the high dielectric strength casting slurry is 25%-50%, the purity of the high dielectric strength ceramic powder is 99%-100%, the particle size is 0.05-50 μm, and the dielectric strength is greater than 40 kV / mm. In some embodiments, the dielectric strength of the high dielectric strength ceramic powder is 40-50 kV / mm. Since the dielectric strength is much higher than that of the casting sheet, the anti-breakdown ability of the casting sheet under high voltage can be significantly improved.

[0051] In some embodiments, the high dielectric strength casting slurry is further doped with a binding aid, which comprises any one of alumina powder and aluminum nitride powder. Since the binding aid has high hardness and good wear resistance, the binding force of the casting sheet can be enhanced, but the mass fraction of the binding aid in the high dielectric strength casting slurry should be less than 5%. If the mass fraction is too high, an electric current path may be formed under high voltage, resulting in an electric arc accident. Preferably, alumina binding aid is added to the tantalum pentoxide casting slurry, and aluminum nitride binding aid is added to the hexagonal boron nitride casting slurry to ensure good material compatibility.

[0052] In some embodiments, the organic solvent comprises one or more of anhydrous ethanol, isopropyl alcohol, acetone and toluene, and the mass fraction of the organic solvent in the high dielectric strength casting slurry is 40%-65%. The organic solvent can well dissolve organic additives such as binders and plasticizers, and help to form a uniform casting slurry.

[0053] In some embodiments, the dispersant includes any one of castor oil phosphate, triethanolamine, and ammonium polyacrylate, and the mass fraction of the dispersant in the high dielectric strength casting slurry is 0.2%-3%. The addition of the dispersant can improve the flowability and stability of the casting slurry, enabling it to exhibit better flowability and formability during the casting process.

[0054] In some embodiments, the binder includes any one of polyvinyl butyral and acrylic acid, and the binder has a mass fraction of 3%-10% in the high dielectric strength casting slurry. The binder has an adhesive effect in the casting slurry, which can enhance the strength and toughness of the preform and facilitate subsequent processing operations.

[0055] In some embodiments, the plasticizer includes any one of butyl benzyl phthalate, butyl phthalate, and dioctyl phthalate, and the plasticizer has a mass fraction of 3%-10% in the high dielectric strength cast slurry. The plasticizer enhances the plasticity of the binder by acting on it, causing the binder to soften in a dry or semi-dry state, thereby improving the flowability and formability of the cast slurry.

[0056] Step 3: Replace the screen printing plate and print the high dielectric strength casting paste at the first gap 31, the second gap 32, the third gap 33 and the fourth gap 34 to obtain the second casting sheet 43.

[0057] like Figure 3 As shown, the green area represents tantalum pentoxide casting paste. Due to the high dielectric strength of tantalum pentoxide casting paste, the gap can be reduced from 3mm to 0.5mm-2.5mm while ensuring that the cast wafer is not broken down under high voltage. At the same time, it can increase the adsorption area between the electrode and the wafer, improve the adsorption force on the wafer, and thus effectively improve the heat dissipation performance and temperature uniformity of the wafer.

[0058] Step 4: Cover the upper surface of the second cast sheet 43 with an alumina cast sheet 41, stack them into a single layer, and make holes at the reserved positions to obtain pin holes 11 and He pores 12, thereby forming a composite ceramic blank 44. Figure 4 This is a schematic cross-sectional view of the composite ceramic preform prepared according to the present invention. The composite ceramic preform 44 is then subjected to debinding and / or sintering to obtain a composite ceramic electrostatic chuck.

[0059] Example 1

[0060] Put 30% by mass of alumina powder (purity 98%, particle size 5 μm), 2% by mass of titanium dioxide powder, 55% by mass of anhydrous ethanol, 1% by mass of castor oil phosphate into a ball mill and mix uniformly to obtain a semi-finished ceramic slurry. Then add 6% by mass of polyvinyl butyral and 6% by mass of butyl benzyl phthalate into the ceramic slurry and mix uniformly to obtain an alumina tape casting slurry.

[0061] Pour the alumina tape casting slurry into a tape casting machine to cast an alumina tape and dry.

[0062] Reserve the positions of pin holes and He gas holes, print a first electrode and a second electrode (bipolar electrode) on the dried alumina tape using a screen printing plate and dry to obtain a first tape, the second electrode is arranged around the first electrode, there is a first gap between the first electrode and the pin holes and He gas holes surrounded by the first electrode, there is a second gap between the outer edge of the first electrode and the inner edge of the second electrode, there is a third gap between the second electrode and the He gas holes surrounded by the second electrode, there is a fourth gap between the outer edge of the second electrode and the outer edge of the alumina tape, the first gap, the second gap, the third gap and the fourth gap are controlled to be 1 mm.

[0063] Put 30% by mass of tantalum pentoxide powder (purity 99%, particle size 5 μm), 2% by mass of alumina powder, 55% by mass of anhydrous ethanol, 1% by mass of castor oil phosphate into a ball mill and mix uniformly to obtain a semi-finished ceramic slurry. Then add 6% by mass of polyvinyl butyral and 6% by mass of butyl benzyl phthalate into the ceramic slurry and mix uniformly to obtain a tantalum pentoxide tape casting slurry.

[0064] Replace the screen printing plate, print the tantalum pentoxide tape casting slurry in the first gap, the second gap, the third gap and the fourth gap and dry to obtain a second tape.

[0065] Cover the second tape with an alumina tape on the surface, stack and form, and open holes in the reserved positions to obtain pin holes and He gas holes, thereby forming a composite ceramic green body, and the composite ceramic green body is de-glued and / or sintered to obtain a composite ceramic electrostatic chuck.

[0066] Example 2

[0067] The 35% by mass aluminum nitride powder (purity 99%, particle size 20 μm), 3% by mass yttrium oxide powder, 52% by mass acetone, and 2% by mass triethanolamine are put into a ball mill and ball-mixed to obtain a semi-finished ceramic slurry. The 4% by mass acrylic acid and 4% by mass butyl phthalate are added to the ceramic slurry, and ball-mixed to obtain an aluminum nitride tape casting slurry.

[0068] The aluminum nitride tape casting slurry is poured into a slurry feeding tank of a casting machine to cast an aluminum nitride tape casting sheet and dry.

[0069] The positions of the pin hole and He gas hole are reserved, a screen printing plate is used to print a metal electrode (single-pole electrode) on the dried aluminum nitride tape casting sheet, and dried to obtain a first tape casting sheet, the gap between the metal electrode and the pin hole and He gas hole is controlled to be 0.5 mm, and the gap between the metal electrode and the outer edge of the aluminum nitride tape casting sheet is controlled to be 0.5 mm.

[0070] The 35% by mass hexagonal boron nitride powder (purity 99%, particle size 20 μm), 3% by mass aluminum nitride powder, 52% by mass acetone, and 2% by mass triethanolamine are put into a ball mill and ball-mixed to obtain a semi-finished ceramic slurry. The 4% by mass acrylic acid and 4% by mass butyl phthalate are added to the ceramic slurry, and ball-mixed to obtain a hexagonal boron nitride tape casting slurry.

[0071] The screen printing plate is replaced, the hexagonal boron nitride tape casting slurry is printed at the gap and dried to obtain a second tape casting sheet.

[0072] A aluminum nitride tape casting sheet is overlaid on the second tape casting sheet, laminated, and a hole is opened at the reserved position to obtain a pin hole and He gas hole, thereby forming a composite ceramic green body, and the composite ceramic green body is subjected to degreasing and / or sintering to obtain a composite ceramic electrostatic chuck.

[0073] In summary, the present application prints any one of high dielectric strength ceramic materials, such as tantalum pentoxide and hexagonal boron nitride, at the gap between the electrodes, and the gap between the electrodes and the outer edge of the ceramic, the pin hole, and the He gas hole. Since the high dielectric strength ceramic material has high dielectric strength, the gap can be reduced to 0.5-2.5 mm while ensuring that the ceramic tape casting sheet is not broken down under high voltage. At the same time, the adsorption area of the electrode and the wafer can be increased, and the adsorption force of the wafer can be improved, thereby effectively improving the heat dissipation performance and temperature uniformity of the wafer.

[0074] While the application has been described in detail and with reference to specific preferred embodiments thereof, it will be apparent to one skilled in the art that various modifications and alternatives can be employed without departing from the spirit and scope of the application. Accordingly, the scope of the application should be determined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a composite ceramic electrostatic chuck, characterized in that, The method includes: Step 1: Provide a ceramic casting sheet with pre-drilled pin holes and helium gas holes. The pin holes are located at the center of the ceramic casting sheet, and the helium gas holes are evenly distributed on the surface of the ceramic casting sheet. Use a screen printing plate to print metal electrodes on the ceramic casting sheet to obtain a first casting sheet. The gap between the metal electrodes and the pin holes and helium gas holes is 0.5mm-2.5mm, and the gap between the metal electrodes and the outer edge of the ceramic casting sheet is 0.5mm-2.5mm. Step 2: Mix high dielectric strength ceramic powder, organic solvent, dispersant, binder and plasticizer to prepare high dielectric strength casting slurry, wherein the high dielectric strength ceramic powder includes any one of tantalum pentoxide and hexagonal boron nitride; Step 3: Replace the screen printing plate and print the high dielectric strength casting paste at the gap to obtain a second casting film; Step 4: Cover the upper surface of the second cast film with a ceramic cast film and stack them together.

2. The manufacturing method of the composite ceramic electrostatic chuck as described in claim 1, characterized in that, The metal electrode includes a first electrode and a second electrode, wherein the second electrode is disposed around the outside of the first electrode, there is a first gap between the first electrode and the pin hole and the helium gas hole it surrounds, there is a second gap between the outer edge of the first electrode and the inner edge of the second electrode, there is a third gap between the second electrode and the helium gas hole it surrounds, and there is a fourth gap between the outer edge of the second electrode and the outer edge of the ceramic casting sheet, wherein the first gap, the second gap, the third gap and the fourth gap are all 0.5mm-2.5mm.

3. The manufacturing method of the composite ceramic electrostatic chuck as described in claim 1, characterized in that, In step 2, the high dielectric strength casting slurry is also doped with a binder, which includes any one of alumina powder and aluminum nitride powder, and the mass fraction of the binder in the high dielectric strength casting slurry is 0-5%.

4. The manufacturing method of the composite ceramic electrostatic chuck as described in claim 1, characterized in that, In step 2, the high dielectric strength ceramic powder has a mass fraction of 25%-50% in the high dielectric strength casting slurry, a purity of 99%-100%, a particle size of 0.05μm-50μm, and a dielectric strength greater than 40kV / mm.

5. The manufacturing method of the composite ceramic electrostatic chuck as described in claim 1, characterized in that, In step 2, the organic solvent comprises one or more of anhydrous ethanol, isopropanol, acetone, and toluene, and the mass fraction of the organic solvent in the high dielectric strength casting slurry is 40%-65%.

6. The manufacturing method of the composite ceramic electrostatic chuck as described in claim 1, characterized in that, In step 2, the dispersant includes any one of castor oil phosphate, triethanolamine, and ammonium polyacrylate, and the mass fraction of the dispersant in the high dielectric strength casting slurry is 0.2%-3%.

7. The manufacturing method of the composite ceramic electrostatic chuck as described in claim 1, characterized in that, In step 2, the binder includes either polyvinyl butyral or acrylic acid, and the mass fraction of the binder in the high dielectric strength casting slurry is 3%-10%.

8. The method for manufacturing the composite ceramic electrostatic chuck as described in claim 1, characterized in that, In step 2, the plasticizer includes any one of butyl benzyl phthalate, butyl phthalate, and dioctyl phthalate, and the mass fraction of the plasticizer in the high dielectric strength casting slurry is 3%-10%.

9. The manufacturing method of the composite ceramic electrostatic chuck as described in claim 1, characterized in that, Following step 4, the method further includes debinding and / or sintering steps.

10. A composite ceramic electrostatic chuck obtained by the manufacturing method according to any one of claims 1-9.

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