Casting slurry for electrostatic chuck, high-performance ceramic material and preparation method of high-performance ceramic material

Abstract

The invention relates to the technical field of semiconductor materials, in particular to tape casting slurry for an electrostatic chuck, a high-performance ceramic material and a preparation method of the high-performance ceramic material. The coating is prepared from the following raw materials in parts by weight: 20-40 parts of mixed powder, 0.1-3 parts of a dispersing agent, 50-70 parts of an organic solvent, 5-50 parts of a binder and 1-30 parts of a plasticizer, the mixed powder comprises alumina powder and glass powder. The magnesium compound, the silicon compound and the calcium compound are firstly synthesized into the high-melting-point sintering additive with the glassy composition, namely the glass powder, and then the glass powder is mixed with the alumina powder, so that the discharge time of residual charges can be shortened, the temperature dependence of the performance of the alumina ceramic material of the ceramic electrostatic chuck is reduced, and good mechanical and electrical performance is kept.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor materials, and in particular to a tape casting slurry for an electrostatic chuck, a high-performance ceramic material and a preparation method thereof. Background Art

[0002] As an efficient wafer clamping tool, the electrostatic chuck plays a vital role in the modern semiconductor manufacturing industry. It firmly clamps the wafer on the chuck through electrostatic adsorption. This feature enables it to avoid the irreversible damage to the wafer caused by mechanical factors such as pressure and collision caused by traditional mechanical chucks. At the same time, the electrostatic chuck can also effectively reduce particle contamination, thereby increasing the effective processing area of ​​the wafer, which is of great significance for improving the quality and output of semiconductor products.

[0003] In addition, compared with vacuum suction cups, electrostatic chucks have a wider range of application environments, especially in low-pressure environments, where electrostatic chucks can show their unique advantages. In order to achieve these functions, electrostatic chucks need to have good thermal conductivity and appropriate volume resistivity. Good thermal conductivity can ensure that the surface temperature of the wafer is uniform during processing, which is crucial to ensuring the processing accuracy of the wafer. The appropriate volume resistivity enables the electrostatic chuck to work stably in a wider temperature range, while providing stable adsorption force and efficient and controllable desorption. Electrostatic chucks are mainly divided into two categories: Johnsen-Rahbek type (JR type for short) and Coulomb type. Both types of electrostatic chucks use the principle of opposite attraction of electrostatic charges to fix silicon wafers, and there is a dielectric layer on the surface in contact with the wafer. However, the dielectric layer materials of these two types of electrostatic chucks are different. The dielectric layer material properties of the JR type electrostatic chuck are not described here, while the dielectric layer of the Coulomb type electrostatic chuck is mainly composed of insulators, and dielectric materials such as insulating ceramics are mostly used to ensure its insulation effect. This design not only enhances the adsorption capacity of the electrostatic chuck, but also improves its stability and reliability. With its unique electrostatic adsorption principle, good thermal conductivity and suitable volume resistivity, the electrostatic chuck plays an irreplaceable role in the modern semiconductor manufacturing industry. Both JR and Coulomb electrostatic chucks have won wide recognition and favor in the industry for their excellent performance and broad application prospects.

[0004] Chinese patent application CN107663080A discloses an alumina ceramic used in a JR type electrostatic chuck and a preparation method thereof. The volume resistivity of the alumina ceramic material obtained can be controlled within 10 within a voltage range of 100-1000V. 9 -10 11Ω·cm, but when the temperature rises from room temperature to about 100℃ to 150℃, it may cause the electrostatic force to change from Coulomb type (high resistance) to Johnen-Rahlbek type (medium resistance), which significantly increases the electrostatic force and prolongs the discharge time of the residual charge, making desorption difficult. Therefore, the ceramic electrostatic chuck increases the temperature dependence of material properties, leading to structural defects and deterioration of electrical / mechanical properties. Summary of the invention

[0005] In order to solve the problems in the prior art, the first aspect of the present invention provides a casting slurry for an electrostatic chuck. The raw materials for preparation include, by weight: 20-40 parts of mixed powder, 0.1-3 parts of dispersant, 50-70 parts of organic solvent, 5-50 parts of binder, and 1-30 parts of plasticizer; the mixed powder includes alumina powder and glass powder.

[0006] In one embodiment, the mass ratio of the aluminum oxide powder to the glass powder is (94-98): (2-6).

[0007] In a preferred embodiment, the mass ratio of the aluminum oxide powder to the glass powder is (95-98):(2-5), which can be 95:2, 95:3, 95:4, 95:5, 96:4, 97:3, 98:2, 98:3, 98:5.

[0008] In one embodiment, the raw materials for preparing the glass powder include at least one of a magnesium compound, a silicon compound, and a calcium compound. Preferably, the raw materials for preparing the glass powder include a magnesium compound, a silicon compound, and a calcium compound.

[0009] In one embodiment, the mass ratio of the magnesium compound, the silicon compound, and the calcium compound is (0.5-2:(0.8-3):(0.5-2).

[0010] In a preferred embodiment, the mass ratio of the magnesium compound, the silicon compound and the calcium compound is (0.6-1.5):(0.8-2):(0.6-1.5), which can be exemplified as: 0.6:0.8:0.6, 0.6:2:1.5, 0.9:1.2:0.9, 1.2:1.6:1.2, 1.5:2:1.5.

[0011] In one embodiment, the magnesium compound comprises magnesium oxide.

[0012] In one embodiment, the silicon compound comprises silicon dioxide.

[0013] In one embodiment, the calcium compound comprises calcium oxide.

[0014] In one embodiment, the preparation method of the glass powder at least comprises: mixing, melting, quenching and crushing a magnesium compound, a silicon compound and a calcium compound to obtain the glass powder.

[0015] In a preferred embodiment, the method for preparing the glass powder comprises:

[0016] Mixing a magnesium compound, a silicon compound, a calcium compound and a solvent in a mixer to obtain a slurry;

[0017] The slurry is placed in a crucible and heated until it melts to obtain a liquid slurry;

[0018] The crucible containing the liquid slurry is quenched with water to obtain a glassy solid slurry;

[0019] The glassy solid slurry is first coarsely crushed into particles with an average particle size of 10-100 μm, and then wet-milled for 24 hours and then dried to obtain the product.

[0020] In one embodiment, the solvent includes one or more of water, anhydrous ethanol, triethyl phosphate, triolein, fish oil, and castor oil.

[0021] In one embodiment, the heating temperature is 1100-1600° C., and the heating time is 1-3 hours. Preferably, the heating temperature is 1400° C., and the heating time is 2 hours.

[0022] In one embodiment, alumina balls are used as grinding media and ethanol is used as solvent in the wet ball milling.

[0023] In one embodiment, the drying temperature is 100° C. and the drying time is 24 hours.

[0024] In one embodiment, the average particle size of the glass powder is 0.5-2 μm, which can be 0.5, 1, 1.5, 2 μm.

[0025] In one embodiment, the dispersant includes at least one of fish oil, corn oil, castor oil, and olein. Preferably, the dispersant is fish oil.

[0026] In one embodiment, the organic solvent includes methyl ethyl ketone, toluene, xylene, ethanol, isopropanol and trichloroethylene. Preferably, the organic solvent is a mixed solvent of methyl ethyl ketone and ethanol.

[0027] In a more preferred embodiment, the volume ratio of methyl ethyl ketone to ethanol is 1:1.

[0028] In one embodiment, the binder includes at least one of polyvinyl butyral and polymethyl methacrylate. Preferably, the binder is polyvinyl butyral.

[0029] In one embodiment, the plasticizer includes at least one of dioctyl phthalate, dibutyl phthalate, and polyethylene glycol. Preferably, the plasticizer is polyethylene glycol.

[0030] A second aspect of the present invention provides a high-performance ceramic material, which is prepared using the electrostatic chuck tape casting slurry.

[0031] The third aspect of the present invention provides a method for preparing a high performance ceramic material, comprising at least the following steps:

[0032] The mixed powder, dispersant, organic solvent, binder and plasticizer are placed in a powder mixing barrel, and the mixed powder is placed on a pot mill and mixed evenly to obtain a casting slurry for an electrostatic chuck;

[0033] Casting the electrostatic chuck casting slurry on a casting machine and drying it to obtain a ceramic sheet;

[0034] At least two of the ceramic sheets are laminated to 2-10 mm, and an electrode layer is arranged between the ceramic sheet laminated products. The ceramic sheet layer and the electrode layer are then sintered together to obtain the high-performance ceramic material.

[0035] In one embodiment, the mixed powder is obtained by uniformly mixing alumina powder and glass powder using a ball mill.

[0036] In one embodiment, the rotation speed of the pot mill is 20-60 r / min, and the ball milling time is 16-30 h. Preferably, the rotation speed of the pot mill is 45 r / min, and the ball milling time is 20 h.

[0037] In one embodiment, the drying temperature is 40-100°C.

[0038] The high-performance ceramic material of the present invention can be formed by laminating multiple ceramic sheets according to needs. In one embodiment, the high-performance ceramic material is formed by laminating two ceramic sheets. The high-performance ceramic material includes a first ceramic sheet layer as an insulating layer / dielectric layer, an electrode layer located on the first ceramic sheet layer, and a second ceramic sheet layer as an insulating layer / dielectric layer located on the electrode layer.

[0039] In one embodiment, the electrode layer is made of a conductive metal material, which includes at least one of silver, gold, nickel, tungsten, molybdenum, titanium, and tungsten.

[0040] In one embodiment, the electrode layer has a thickness of 2-30 μm.

[0041] In one embodiment, the sintering includes debinding and high temperature sintering.

[0042] In a preferred embodiment, the debinding temperature is 500-700°C, preferably 600°C.

[0043] In a preferred embodiment, the high temperature sintering temperature is 1500-1700°C, preferably 1650°C.

[0044] In one embodiment, the high temperature sintering time is 120-200 hours, preferably 160 hours.

[0045] Beneficial Effects

[0046] 1. The present invention obtains glass powder by mixing, melting, quenching and pulverizing a slurry containing a magnesium compound, a silicon compound and a calcium compound, which can promote the sintering property of a ceramic substrate and make the ceramic substrate have a density of more than 98%.

[0047] 2. The present invention adds alumina powder and glass powder in a mass ratio of (95-98): (2-5) so that the sintered ceramic material obtains a high volume resistivity value.

[0048] 3. The present invention synthesizes a high melting point sintering additive having a glassy composition, namely glass powder, from magnesium compounds, silicon compounds and calcium compounds, and then mixes the mixture with alumina powder, thereby reducing the discharge time of residual charge, reducing the temperature dependence of the performance of alumina ceramic materials of ceramic electrostatic chucks, and maintaining good mechanical and electrical properties.

[0049] 4. The present invention provides a method for preparing high-performance ceramic materials, which has a simple preparation process and good practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the structure of the high-performance ceramic material prepared in Example 4. In the figure, 300. high-performance ceramic material (ie, ceramic plate), 310. first ceramic sheet layer, 320. electrode layer, 330. second ceramic sheet layer.

[0051] Figure 2 The volume resistivity of the ceramic materials of various embodiments and comparative examples varies with temperature. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the examples and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The experimental methods for which specific conditions are not specified in the examples are carried out under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used that do not specify the manufacturer are all conventional products that can be purchased commercially.

[0053] Example 1

[0054] The first aspect of this embodiment provides a casting slurry for an electrostatic chuck. The raw materials for preparation include, by weight: 40 parts of mixed powder, 0.5 parts of dispersant, 60 parts of organic solvent, 25 parts of binder, and 5 parts of plasticizer; the mixed powder includes alumina powder and glass powder.

[0055] The dispersant is fish oil.

[0056] The organic solvent is a mixed solvent of methyl ethyl ketone and ethanol, and the volume ratio of the methyl ethyl ketone to the ethanol is 1:1.

[0057] The binder is polyvinyl butyral.

[0058] The plasticizer is polyethylene glycol.

[0059] The mass ratio of the alumina powder to the glass powder is 95:5.

[0060] The glass powder is magnesium oxide, silicon dioxide and calcium oxide, and the mass ratio of magnesium oxide, silicon dioxide and calcium oxide is 1.5:2:1.5.

[0061] The preparation method of the glass powder comprises:

[0062] Mixing magnesium oxide, silicon dioxide and calcium oxide with anhydrous ethanol in a mixer to obtain a slurry;

[0063] The mass ratio of the magnesium oxide, silicon dioxide and calcium oxide to the anhydrous ethanol is 1:1;

[0064] The slurry is placed in a crucible and heated until it melts to obtain a liquid slurry;

[0065] The crucible containing the liquid slurry is quenched with water to obtain a glassy solid slurry;

[0066] The glassy solid slurry is first coarsely crushed into particles with an average particle size of 10-100 μm, and then wet ball-milled for 24 hours and dried at 100° C. for 24 hours to obtain the product.

[0067] The heating temperature is 1400° C. and the heating time is 2 hours. Alumina balls are used as grinding media and ethanol is used as solvent in the wet ball milling.

[0068] The average particle size of the glass powder is 2 μm.

[0069] A second aspect of this embodiment provides a high-performance ceramic material, which is prepared using the electrostatic chuck tape casting slurry.

[0070] A third aspect of the present embodiment provides a method for preparing a high-performance ceramic material, comprising at least the following steps:

[0071] The mixed powder, dispersant, organic solvent, binder and plasticizer are placed in a powder mixing barrel, and the mixture is placed on a pot mill to mix evenly to obtain a casting slurry for an electrostatic chuck; the rotation speed of the pot mill is 45 r / min, and the ball milling time is 20 h;

[0072] Casting the electrostatic chuck casting slurry on a casting machine and drying it to obtain a ceramic sheet;

[0073] The two ceramic sheets are laminated to 2 mm, and an electrode layer is arranged between the ceramic sheet laminated products. The ceramic sheet layer and the electrode layer are then sintered together to obtain the high-performance ceramic material.

[0074] The mixed powder is obtained by uniformly mixing alumina powder and glass powder using a ball mill.

[0075] The drying temperature is 60°C.

[0076] The electrode layer is made of a conductive metal material, which is tungsten, and has a thickness of 5 μm.

[0077] The sintering includes debinding and high-temperature sintering. The debinding temperature is 600° C. The high-temperature sintering temperature is 1650° C. and the time is 160 hours.

[0078] Example 2

[0079] The specific implementation of this embodiment is the same as that of Embodiment 1, except that:

[0080] The mass ratio of the alumina powder to the glass powder is 96:4.

[0081] The glass powder is magnesium oxide, silicon dioxide and calcium oxide, and the mass ratio of magnesium oxide, silicon dioxide and calcium oxide is 1.2:1.6:1.2.

[0082] Example 3

[0083] The specific implementation of this embodiment is the same as that of Embodiment 1, except that:

[0084] The mass ratio of the alumina powder to the glass powder is 97:3.

[0085] The glass powder is magnesium oxide, silicon dioxide and calcium oxide, and the mass ratio of magnesium oxide, silicon dioxide and calcium oxide is 0.9:1.2:0.9.

[0086] Example 4

[0087] The specific implementation of this embodiment is the same as that of Embodiment 1, except that:

[0088] The mass ratio of the alumina powder to the glass powder is 98:2.

[0089] The glass powder is magnesium oxide, silicon dioxide and calcium oxide, and the mass ratio of magnesium oxide, silicon dioxide and calcium oxide is 0.6:0.8:0.6.

[0090] Figure 1 This is a schematic diagram of the structure of the high-performance ceramic material prepared in Example 4. In the figure, 300. high-performance ceramic material (ie, ceramic plate), 310. first ceramic sheet layer, 320. electrode layer, 330. second ceramic sheet layer.

[0091] Comparative Example 1

[0092] The specific implementation of this comparative example is the same as that of Example 2, except that in this comparative example, alumina powder is directly used together with magnesium oxide, silicon dioxide and calcium oxide to prepare the casting slurry.

[0093] Figure 2 The volume resistivity of the ceramic materials of various embodiments and comparative examples varies with temperature.

[0094] Performance test methods and data

[0095] The density and volume resistivity of the ceramic materials prepared in each embodiment and comparative example were tested. The density test was carried out in accordance with the national standard GB / T 25995-2010, and the volume resistivity test was carried out in accordance with the standard GB / T31838.7-2021. The test data are shown in Tables 1 and Figure 2 shown.

[0096] Table 1

[0097] sample Density Volume resistivity (Ω·cm / 200℃) Example 1 99.92％ 1.35E+15 Example 2 99.97％ 2.35E+15 Example 3 99.96％ 4.35E+15 Example 4 99.97％ 4.35E+15 Comparative Example 1 99.95％ 2.00E+14

[0098] from Figure 2 It can be seen from the experimental data that the system resistivity of the ceramic material prepared by the present invention changes slightly with temperature, which reduces the temperature dependence of the material performance.

Claims

1. A casting slurry for an electrostatic chuck, characterized in that: The raw materials include, by weight: 20-40 parts of mixed powder, 0.1-3 parts of dispersant, 50-70 parts of organic solvent, 5-50 parts of binder, and 1-30 parts of plasticizer; the mixed powder includes alumina powder and glass powder.

2. The casting slurry for electrostatic chuck according to claim 1, characterized in that: The mass ratio of the alumina powder to the glass powder is (94-98):(2-6).

3. The casting slurry for electrostatic chuck according to claim 1, characterized in that: The raw materials for preparing the glass powder include at least one of a magnesium compound, a silicon compound, and a calcium compound.

4. The casting slurry for electrostatic chuck according to claim 3, characterized in that: The mass ratio of the magnesium compound, the silicon compound and the calcium compound is (0.5-2):(0.8-3):(0.5-2).

5. The casting slurry for electrostatic chuck according to claim 3 or 4, characterized in that: The preparation method of the glass powder at least comprises: mixing, melting, quenching and crushing a magnesium compound, a silicon compound and a calcium compound to obtain the glass powder.

6. The casting slurry for electrostatic chuck according to claim 5, characterized in that: The preparation method of the glass powder comprises: Mixing a magnesium compound, a silicon compound, a calcium compound and a solvent in a mixer to obtain a slurry; The slurry is placed in a crucible and heated until it melts to obtain a liquid slurry; The crucible containing the liquid slurry is quenched with water to obtain a glassy solid slurry; The glassy solid slurry is first coarsely crushed into particles with an average particle size of 10-100 μm, and then wet-milled for 24 hours and then dried to obtain the product.

7. The casting slurry for electrostatic chuck according to claim 6, characterized in that: Alumina balls are used as grinding media and ethanol is used as solvent in the wet ball milling.

8. The casting slurry for electrostatic chuck according to claim 6, characterized in that: The average particle size of the glass powder is 0.5-2 μm.

9. A high performance ceramic material, characterized in that: The electrostatic chuck is prepared by using the casting slurry for electrostatic chuck according to any one of claims 1 to 8.

10. A method for preparing a high performance ceramic material according to claim 9, characterized in that: At least the following steps are included: The mixed powder, dispersant, organic solvent, binder and plasticizer are placed in a powder mixing barrel, and the mixed powder is placed on a pot mill and mixed evenly to obtain a casting slurry for an electrostatic chuck; The electrostatic chuck is subjected to tape casting and drying on a tape casting machine using a tape casting slurry to obtain a ceramic sheet; At least two of the ceramic sheets are laminated to 2-10 mm, and an electrode layer is arranged between the ceramic sheet laminated products. The ceramic sheet layer and the electrode layer are then sintered together to obtain the high-performance ceramic material.

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