Method for reducing corrosion of heating wire of aluminum nitride heating plate

Abstract

The invention discloses a method for reducing corrosion of a heating wire of an aluminum nitride heating plate, and belongs to the technical field of electrostatic chucks, and the method comprises the following steps: S1, preparing aluminum nitride granulation powder added with yttrium oxide through centrifugal spray granulation; s2, forming an aluminum nitride heating plate green body by using a dry pressing mold; S3, carrying out green body glue removal on the aluminum nitride heating plate in an air atmosphere glue removal furnace, wherein the green body glue removal amount is 3.5-5.5%; s4, a graphite hot pressing furnace is adopted for sintering, the pressurization temperature point is 1200-1500 DEG C, the pressurization pressure is 15-35 MPa, the heating rate is 3-5 DEG C / min, the high temperature is 1700-1850 DEG C, high-temperature heat preservation is conducted for 4-8 hours, and the cooling rate is 0.5-2 DEG C / min; in combination with an aluminum nitride ceramic sintering liquid phase temperature point and a crystal grain rapid development temperature point, carbon is discharged as much as possible in the initial stage of sintering by controlling the pressurization pressure and a proper pressurization temperature point during sintering, and development densification of crystal grains is completed before carbon volatilization of a heating rod in the middle stage of sintering; and carbon diffusion into the aluminum nitride ceramic body from the heating rod of the hot-pressing furnace is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of electrostatic chucks, and in particular to a method for reducing corrosion of heating wires of an aluminum nitride heating disk. Background Art

[0002] In the prior art, a single-zone or dual-zone aluminum nitride ceramic heating plate is prepared by a pressing molding process, and a high-purity molybdenum wire (purity > 99.5%) is used as the heating wire. The heating wire is embedded in the aluminum nitride green body during the molding process, and then degreased and sintered to obtain the aluminum nitride heating plate.

[0003] By changing the ceramic formula of the aluminum nitride heating plate and refining its grains, the corrosion of the built-in heating wire can be reduced. However, due to the significant increase in the number of introduced grain boundaries, the thermal conductivity of the ceramic body is significantly reduced (for example, the thermal conductivity is reduced from 180-200W / m·K to 50-70W / m·K).

[0004] The disadvantage of the prior art is that during the sintering process in the hot pressing furnace, carbon from the heating rod inevitably diffuses into the aluminum nitride ceramic body at a high temperature, thereby causing a high-temperature reaction between molybdenum and carbon and causing corrosion. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for reducing the corrosion of the heating wire of the aluminum nitride heating disk, so as to solve the problem raised in the background technology.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] The present invention discloses a method for reducing corrosion of a heating wire of an aluminum nitride heating disk, the method comprising:

[0008] S1: preparing aluminum nitride granulated powder added with yttrium oxide by centrifugal spray granulation, wherein the addition ratio of yttrium oxide as a sintering aid is 2-5wt%;

[0009] S2: Green forming of aluminum nitride heating plate using dry pressing mold:

[0010] According to the size of the heating plate, the compression ratio of the powder and the sintering shrinkage ratio, the thickness of each layer is controlled by filling powder so that the size requirements are met after sintering. The specific molding process is as follows:

[0011] Filling powder - pressing - putting in heating wire - filling powder - pressing - demoulding, to obtain a green body of an aluminum nitride heating plate with a built-in heating wire, wherein the density of the green body of the aluminum nitride heating plate is 1.8-2.0 g / cm3, and the heating wire is a molybdenum wire;

[0012] S3: debinding the aluminum nitride heating plate green body in an air atmosphere debinding furnace, wherein the debinding amount of the aluminum nitride heating plate green body is 3.5-5.5%;

[0013] S4: sintering is carried out in a graphite hot press furnace, with a pressurizing temperature of 1200-1500°C, a pressurizing pressure of 15-35MPa, a heating rate of 3-5°C / min, a high temperature of 1700-1850°C, a high temperature holding time of 4-8 hours, and a cooling rate of 0.5-2°C / min;

[0014] Combined with the sintering liquid phase temperature point of aluminum nitride ceramics and the temperature point at which the grains develop rapidly, by controlling the pressurization pressure during sintering and the appropriate pressurization temperature point, as much carbon as possible is discharged in the early stage of sintering, and the development and densification of the grains are completed before the carbon of the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon from the heating rod of the hot pressing furnace into the aluminum nitride ceramic body;

[0015] S5: Process the sintered aluminum nitride heating plate and detect the resistance of its built-in molybdenum wire;

[0016] The aluminum nitride heating plate that has just been sintered is cut into samples, and the location of the molybdenum wire is taken for scanning electron microscopy inspection.

[0017] Preferably, in step S1, the moisture content of the aluminum nitride granulated powder is less than 1%, the bulk density is 0.8 to 1.5 g / cm3, and the powder particle size D50 is 70 to 90 μm.

[0018] Preferably, the heating wire in step S2 is a molybdenum wire with a purity of 99.5% or above.

[0019] Preferably, when debinding the aluminum nitride heating plate green body in step S3, the debinding temperature is 350-450°C, the heating rate is 0.5-1.5°C / min, the high temperature holding time is 10-14 hours, and the cooling rate is 1.0-3.0°C / min.

[0020] The above technical solution has the following beneficial effects:

[0021] The aluminum nitride heating plate in the technical solution of the present invention greatly reduces the corrosion degree of the built-in heating wire by combining the pressurization temperature point and the pressurization pressure;

[0022] The aluminum nitride heating plate in the technical solution of the present invention is optimized by reducing the degree of corrosion of the heating wire through the process, and the formula of its ceramic body is not changed, thereby ensuring its excellent thermal conductivity performance;

[0023] The aluminum nitride heating plate in the technical solution of the present invention has a simple preparation process, short procedures and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 These are electron microscope scanning photos of molybdenum wires at different pressurized temperature points of the present invention;

[0025] Figure 2 These are scanning electron microscope photos of the molybdenum wires at different pressurization pressures of the present invention. DETAILED DESCRIPTION

[0026] 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.

[0027] Example 1

[0028] A method for reducing corrosion of a heating wire of an aluminum nitride heating disk, comprising:

[0029] S1: Prepare aluminum nitride granulated powder with added yttrium oxide by centrifugal spray granulation, wherein the addition ratio of yttrium oxide as a sintering aid is 2-5wt%, the moisture content of the aluminum nitride granulated powder is less than 1%, and the bulk density is 0.8-1.5g / cm 3 , powder particle size D50 = 70 ~ 90μm;

[0030] S2: Green forming of aluminum nitride heating plate using dry pressing mold:

[0031] According to the size of the heating plate, the compression ratio of the powder and the sintering shrinkage ratio, the thickness of each layer is controlled by filling powder so that the size requirements are met after sintering. The specific molding process is as follows:

[0032] Filling powder - pressing - putting in heating wire - filling powder - pressing - demoulding, to obtain the aluminum nitride heating plate green body with built-in heating wire, wherein the density of the aluminum nitride heating plate green body is 1.8-2.0 g / cm 3 , the heating wire is a molybdenum wire with a purity of 99.5%. In other implementations of this embodiment, the purity of the molybdenum wire is greater than 99.5%;

[0033] S3: debinding the aluminum nitride heating plate green body in an air atmosphere debinding furnace, the debinding amount of the aluminum nitride heating plate green body is 3.5-5.5%, the debinding temperature is 350-450°C, the heating rate is 0.5-1.5°C / min, the high temperature holding time is 10-14 hours, and the cooling rate is 1.0-3.0°C / min;

[0034] S4: sintering is carried out in a graphite hot press furnace, with a pressurizing temperature of 1200-1500°C, a pressurizing pressure of 15-35MPa, a heating rate of 3-5°C / min, a high temperature of 1700-1850°C, a high temperature insulation of 4-8 hours, and a cooling rate of 0.5-2°C / min;

[0035] Combined with the sintering liquid phase temperature of aluminum nitride ceramics and the temperature point at which the grains develop rapidly, the pressurization pressure during sintering is controlled to a temperature point of 1200-1500°C. The appropriate pressurization temperature point can discharge as much carbon as possible at the initial stage of sintering, and complete the development and densification of the grains before the carbon in the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon in the heating rod of the hot pressing furnace into the aluminum nitride ceramic body;

[0036] S5: Process the sintered aluminum nitride heating plate and detect the resistance of its built-in molybdenum wire;

[0037] The aluminum nitride heating plate that has just been sintered is cut into samples, and the location of the molybdenum wire is taken for scanning electron microscopy inspection.

[0038] Example 2

[0039] A method for reducing corrosion of a heating wire of an aluminum nitride heating disk, comprising:

[0040] S1: Prepare aluminum nitride granulated powder with added yttrium oxide by centrifugal spray granulation, wherein the addition ratio of yttrium oxide as a sintering aid is 2wt%, the moisture content of the aluminum nitride granulated powder is less than 1%, and the bulk density is 0.8g / cm 3 , powder particle size D50 = 70 μm;

[0041] S2: Green forming of aluminum nitride heating plate using dry pressing mold:

[0042] According to the size of the heating plate, the compression ratio of the powder and the sintering shrinkage ratio, the thickness of each layer is controlled by filling powder so that the size requirements are met after sintering. The specific molding process is as follows:

[0043] Filling powder - pressing - putting in heating wire - filling powder - pressing - demoulding, to obtain the aluminum nitride heating plate green body with built-in heating wire, wherein the density of the aluminum nitride heating plate green body is 1.8g / cm 3 , the heating wire is a molybdenum wire with a purity of 99.6%;

[0044] S3: Debinding the aluminum nitride heating plate green body in an air atmosphere debinding furnace, the debinding amount of the aluminum nitride heating plate green body is 3.5%, the debinding temperature is 350°C, the heating rate is 0.5°C / min, the high temperature holding time is 10 hours, and the cooling rate is 1.0°C / min;

[0045] S4: sintering was carried out in a graphite hot press furnace, with a pressurizing temperature of 1200°C, a pressurizing pressure of 15 MPa, a heating rate of 3°C / min, a high temperature of 1700°C, a high temperature insulation of 4 hours, and a cooling rate of 0.5°C / min;

[0046] Combined with the sintering liquid phase temperature of aluminum nitride ceramics and the temperature point where the grains develop rapidly, by controlling the pressurization pressure during sintering, the pressurization temperature point is 1200℃. Through the appropriate pressurization temperature point, as much carbon as possible is discharged at the early stage of sintering, and the development and densification of the grains are completed before the heating rod carbon volatilizes in the middle stage of sintering, thereby reducing the diffusion of the heating rod carbon in the hot press furnace into the aluminum nitride ceramic body;

[0047] S5: Process the sintered aluminum nitride heating plate and detect the resistance of its built-in molybdenum wire;

[0048] The aluminum nitride heating plate that has just been sintered is cut into samples, and the location of the molybdenum wire is taken for scanning electron microscopy inspection.

[0049] Example 3

[0050] A method for reducing corrosion of a heating wire of an aluminum nitride heating disk, comprising:

[0051] S1: Aluminum nitride granulated powder with yttrium oxide added was prepared by centrifugal spray granulation, wherein the addition ratio of yttrium oxide as a sintering aid was 5wt%, the moisture content of the aluminum nitride granulated powder was 0.8%, and the bulk density was 1.5g / cm 3 , powder particle size D50 = 90 μm;

[0052] S2: Green forming of aluminum nitride heating plate using dry pressing mold:

[0053] According to the size of the heating plate, the compression ratio of the powder and the sintering shrinkage ratio, the thickness of each layer is controlled by filling powder so that the size requirements are met after sintering. The specific molding process is as follows:

[0054] Filling powder - pressing - putting in heating wire - filling powder - pressing - demoulding, to obtain the aluminum nitride heating plate green body with built-in heating wire, wherein the density of the aluminum nitride heating plate green body is 2.0g / cm 3 , the heating wire is a molybdenum wire with a purity of 99.7%;

[0055] S3: debinding the aluminum nitride heating plate green body in an air atmosphere debinding furnace, the debinding amount of the aluminum nitride heating plate green body is 5.5%, the debinding temperature is 450°C, the heating rate is 1.5°C / min, the high temperature holding time is 14 hours, and the cooling rate is 3.0°C / min;

[0056] S4: sintering was carried out in a graphite hot press furnace, with a pressurizing temperature of 1500°C, a pressurizing pressure of 35MPa, a heating rate of 5°C / min, a high temperature of 1850°C, a high temperature insulation of 8 hours, and a cooling rate of 2°C / min;

[0057] Combined with the liquid phase temperature point of aluminum nitride ceramic sintering and the temperature point of rapid grain development, by controlling the pressurization pressure during sintering and using the appropriate pressurization temperature point, as much carbon as possible is discharged at the early stage of sintering, and the development and densification of grains are completed before the carbon of the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon from the heating rod of the hot press furnace into the aluminum nitride ceramic body;

[0058] S5: Process the sintered aluminum nitride heating plate and detect the resistance of its built-in molybdenum wire;

[0059] The aluminum nitride heating plate that has just been sintered is cut into samples, and the location of the molybdenum wire is taken for scanning electron microscopy inspection.

[0060] Example 4

[0061] The aluminum nitride heating plate was sintered in a graphite hot pressing furnace, wherein the pressurizing temperature points were set to 1200°C, 1300°C, 1400°C, and 1500°C, and the pressurizing pressure was 25MPa. The molybdenum wires at the above four different pressurizing temperature points were subjected to scanning electron microscopy to observe the corrosion of the molybdenum wire surface. The distribution of the room temperature thermal conductivity and the heating wire resistance value is shown in Table 1.

[0062] Table 1:

[0063] Serial number Pressurization pressure / MPa Heating temperature point / ℃ Room temperature thermal conductivity (W / mk) Heating wire resistance value / Ω 1 25 1200 170 30 2 25 1300 175 16 3 25 1400 195 8 4 25 1500 185 14

[0064] It can be seen from Table 1 that when the pressurized pressure is 25 MPa and the heating temperature is 1400 degrees Celsius, the maximum room temperature thermal conductivity is 195 and the resistance value of the heating wire is 8 ohms.

[0065] Example 5

[0066] The aluminum nitride heating plate was sintered in a graphite hot pressing furnace, where the pressurizing temperature was set at 1300°C, and the pressurizing pressure was set at 15MPa, 20MPa, 25MPa, and 30MPa. The molybdenum wires with different pressurizing pressures were tested by scanning electron microscopy to observe the corrosion of the molybdenum wire surface. The distribution of room temperature thermal conductivity and heating wire resistance is shown in Table 2.

[0067] Table 2:

[0068] Serial number Pressurization pressure / MPa Heating temperature point / ℃ Room temperature thermal conductivity (W / mk) Heating wire resistance value / Ω 5 15 1300 110 25 6 20 1300 135 20 7 25 1300 173 16 8 30 1300 115 7

[0069] refer to Figure 1 and Figure 2 , Figure 1 The scanning electron microscope photos of the molybdenum wire at different pressurized temperatures of the present invention are 1200°C, 1300°C, 1400°C, and 1500°C. Figure 2 The scanning electron microscope photos of molybdenum wires at different pressures of the present invention are shown in Figure 1. The different pressures are 15MPa, 20MPa, 25MPa, and 30MPa. Figure 1 , Figure 2 From the analysis of the various pictures, the higher the resistance of the molybdenum wire, the greater the corrosion. Figure 1 , Figure 2 The larger the loose area around the electron microscope photo, the greater the corrosion. Figure 1 Among them, when the heating temperature is 1400 degrees Celsius, the rack pressure is 25MPa, the room temperature thermal conductivity is the largest, and the molybdenum wire cross-section corrosion is small, which is the best choice.

[0070] 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 reducing corrosion of heating wires of aluminum nitride heating plates, characterized in that: The method comprises: S1: preparing aluminum nitride granulated powder added with yttrium oxide by centrifugal spray granulation, wherein the addition ratio of yttrium oxide as a sintering aid is 2-5wt%; S2: Green forming of aluminum nitride heating plate using dry pressing mold: According to the size of the heating plate, the compression ratio of the powder and the sintering shrinkage ratio, the thickness of each layer is controlled by filling powder so that the size requirements are met after sintering. The specific molding process is as follows: Filling powder - pressing - putting in heating wire - filling powder - pressing - demoulding, to obtain the aluminum nitride heating plate green body with built-in heating wire, wherein the density of the aluminum nitride heating plate green body is 1.8-2.0 g / cm 3 , the heating wire is molybdenum wire; S3: debinding the aluminum nitride heating plate green body in an air atmosphere debinding furnace, wherein the debinding amount of the aluminum nitride heating plate green body is 3.5-5.5%; S4: sintering is carried out in a graphite hot press furnace, with a pressurizing temperature of 1200-1500°C, a pressurizing pressure of 15-35MPa, a heating rate of 3-5°C / min, a high temperature of 1700-1850°C, a high temperature holding time of 4-8 hours, and a cooling rate of 0.5-2°C / min; Combined with the sintering liquid phase temperature point of aluminum nitride ceramics and the temperature point at which the grains develop rapidly, by controlling the pressurization pressure during sintering and the appropriate pressurization temperature point, as much carbon as possible is discharged in the early stage of sintering, and the development and densification of the grains are completed before the carbon of the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon from the heating rod of the hot pressing furnace into the aluminum nitride ceramic body; S5: Process the sintered aluminum nitride heating plate and detect the resistance of its built-in molybdenum wire; The aluminum nitride heating plate that has just been sintered is cut into samples, and the location of the molybdenum wire is taken for scanning electron microscopy inspection.

2. The method for reducing corrosion of heating wires of aluminum nitride heating disks according to claim 1, characterized in that: In step S1, the moisture content of the aluminum nitride granulated powder is less than 1%, and the bulk density is 0.8-1.5 g / cm 3 , powder particle size D50 = 70 ~ 90μm.

3. The method for reducing corrosion of heating wires of aluminum nitride heating disks according to claim 1, characterized in that: The heating wire in step S2 is a molybdenum wire with a purity of 99.5% or above.

4. The method for reducing corrosion of heating wires of aluminum nitride heating disks according to claim 1, characterized in that: When debinding the aluminum nitride heating plate green body in step S3, the debinding temperature is 350-450° C., the heating rate is 0.5-1.5° C. / min, the high temperature holding time is 10-14 hours, and the cooling rate is 1.0-3.0° C. / min.

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