A method for reducing corrosion of heating wires in aluminum nitride heating plates

Abstract

This invention discloses a method for reducing the corrosion of the heating wire in an aluminum nitride heating plate, belonging to the field of electrostatic chuck technology, comprising: S1: preparing yttrium oxide-added aluminum nitride granulated powder by centrifugal spray granulation; S2: forming the aluminum nitride heating plate green blank using a dry pressing mold; S3: removing the binder from the aluminum nitride heating plate green blank in an air atmosphere debinding furnace, with a debinding amount of 3.5-5.5%; S4: sintering using a graphite hot press furnace, with a pressing temperature of 1200-1500℃ and a pressing pressure of 15-15℃. 35 MPa, heating rate 3-5℃ / min, high temperature 1700-1850℃, high temperature holding for 4-8 hours, cooling rate 0.5-2℃ / min; combining the sintering liquid phase temperature point and the temperature point for rapid grain development of aluminum nitride ceramics, by controlling the pressure and appropriate pressure temperature during sintering, as much carbon as possible is discharged in the early stage of sintering, and the grain development and densification are completed before the carbon in the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon from the heating rod into the aluminum nitride ceramic body.

Description

Technical Field

[0001] This invention relates to the field of electrostatic chuck technology, and in particular to a method for reducing corrosion of the heating wire in an aluminum nitride heating plate. Background Technology

[0002] In the prior art, single-zone or double-zone aluminum nitride ceramic heating plates are prepared by pressing and molding process. High-purity molybdenum wire (purity > 99.5%) is used as the heating wire. The heating wire is embedded in the aluminum nitride green blank during the molding process, and then degreasing and sintering are performed to obtain the aluminum nitride heating plate.

[0003] By changing the ceramic formula of the aluminum nitride heating plate, its grains are refined, which reduces the corrosion of the built-in heating wire. However, at the same time, the number of introduced grain boundaries increases significantly, resulting in a significant decrease in the thermal conductivity of the ceramic body (e.g., thermal conductivity decreases from 180-200 W / m·K to 50-70 W / m·K).

[0004] The shortcoming of the existing technology is that during the sintering process in the hot press furnace, carbon diffusion from the heating rods inevitably occurs at high temperatures and enters the aluminum nitride ceramic body, which leads to a high-temperature reaction between molybdenum and carbon, resulting in 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 in an aluminum nitride heating plate, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] This invention discloses a method for reducing corrosion of the heating wire in an aluminum nitride heating plate, the method comprising:

[0008] S1: Aluminum nitride granulated powder with added yttrium oxide was prepared by centrifugal spray granulation, wherein the proportion of yttrium oxide added as a sintering aid was 2-5 wt%.

[0009] S2: Forming the aluminum nitride heating plate preform using a dry pressing mold:

[0010] Based on the size of the heating plate, as well as the compression ratio and sintering shrinkage ratio of the powder, the thickness of each layer is controlled by filling with powder to ensure that it meets the dimensional requirements after sintering. The specific molding process is as follows:

[0011] The process involves filling powder, pressing, inserting heating wire, filling powder, pressing, and demolding to obtain a green aluminum nitride heating plate with an internal heating wire. The density of the green aluminum nitride heating plate is 1.8–2.0 g / cm³, and the heating wire is molybdenum wire.

[0012] S3: The aluminum nitride heating plate green blank is degummed in an air atmosphere degumming furnace, and the degumming amount of the aluminum nitride heating plate green blank is 3.5-5.5%;

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

[0014] By combining the liquid phase temperature point of aluminum nitride ceramic sintering and the temperature point of rapid grain development, and by controlling the pressure during sintering and the appropriate pressure temperature point, as much carbon as possible is discharged in the early stage of sintering, and the grain development and densification are completed before the carbon in the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon from the heating rod in the hot press furnace into the aluminum nitride ceramic body.

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

[0016] The aluminum nitride heating plate that has been sintered and removed from the furnace is cut into samples, and the location of the molybdenum wire is examined by scanning electron microscopy.

[0017] Preferably, in step S1, the aluminum nitride granulated powder has a moisture content of <1%, a loose packing density of 0.8-1.5 g / cm3, and a particle size D50 of 70-90 μm.

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

[0019] Preferably, in step S3, when removing the binder from the aluminum nitride heating plate, the binder removal temperature is 350-450℃, the heating rate is 0.5-1.5℃ / min, the high-temperature holding time is 10-14 hours, and the cooling rate is 1.0-3.0℃ / min.

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

[0021] The aluminum nitride heating plate in this invention greatly reduces the corrosion of the built-in heating wire by controlling the combined pressure and temperature point.

[0022] The aluminum nitride heating plate in the technical solution of this invention optimizes the process to reduce the corrosion of the heating wire, without changing the formula of its ceramic body, thus ensuring its excellent thermal conductivity.

[0023] The aluminum nitride heating plate of the present invention has a simple manufacturing process, short steps, and low cost. Attached Figure Description

[0024] Figure 1 These are scanning electron microscope images of the molybdenum wire at different pressure temperatures according to the present invention;

[0025] Figure 2 These are scanning electron microscope images of molybdenum wire under different pressures according to the present invention. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, 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 the heating wire in an aluminum nitride heating plate includes:

[0029] S1: Aluminum nitride granulated powder with added yttrium oxide was prepared by centrifugal spray granulation, wherein the proportion of yttrium oxide as a sintering aid was 2-5 wt%, the moisture content of the aluminum nitride granulated powder was <1%, and the loose packing density was 0.8-1.5 g / cm³. 3 Particle size D50 of the powder is 70-90 μm;

[0030] S2: Forming the aluminum nitride heating plate preform using a dry pressing mold:

[0031] Based on the size of the heating plate, as well as the compression ratio and sintering shrinkage ratio of the powder, the thickness of each layer is controlled by filling with powder to ensure that it meets the dimensional requirements after sintering. The specific molding process is as follows:

[0032] The process involves filling with powder, pressing, inserting a heating wire, filling with powder again, pressing again, and demolding to obtain a green aluminum nitride heating plate with an internal heating wire. The density of the green aluminum nitride heating plate is 1.8–2.0 g / cm³. 3 The heating wire is a molybdenum wire with a purity of 99.5%. In other embodiments of this example, the purity of the molybdenum wire is 99.5% or higher.

[0033] S3: The aluminum nitride heating plate green blank is degummed in an air atmosphere degumming furnace. The degumming amount of the aluminum nitride heating plate green blank is 3.5-5.5%, the degumming temperature is 350-450℃, the heating rate is 0.5-1.5℃ / min, the high temperature holding time is 10-14 hours, and the cooling rate is 1.0-3.0℃ / min.

[0034] S4: Sintering is carried out in a graphite hot press furnace with a pressurization temperature of 1200-1500℃, a pressurization pressure of 15-35MPa, a heating rate of 3-5℃ / min, a high temperature of 1700-1850℃, a high temperature holding time of 4-8 hours, and a cooling rate of 0.5-2℃ / min.

[0035] By combining the liquid phase temperature point of aluminum nitride ceramic sintering and the temperature point of rapid grain development, the pressure during sintering is controlled, and the pressure temperature point is 1200-1500℃. With a suitable pressure temperature point, as much carbon as possible is discharged in the early stage of sintering, and the grain development and densification are completed before the carbon in the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon from the heating rod in the hot press furnace into the aluminum nitride ceramic body.

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

[0037] The aluminum nitride heating plate that has been sintered and removed from the furnace is cut into samples, and the location of the molybdenum wire is examined by scanning electron microscopy.

[0038] Example 2

[0039] A method for reducing corrosion of the heating wire in an aluminum nitride heating plate includes:

[0040] S1: Aluminum nitride granulated powder with added yttrium oxide was prepared by centrifugal spray granulation, wherein the proportion of yttrium oxide as a sintering aid was 2wt%, the moisture content of the aluminum nitride granulated powder was <1%, and the loose packing density was 0.8 g / cm³. 3 Powder particle size D50 = 70μm;

[0041] S2: Forming the aluminum nitride heating plate preform using a dry pressing mold:

[0042] Based on the size of the heating plate, as well as the compression ratio and sintering shrinkage ratio of the powder, the thickness of each layer is controlled by filling with powder to ensure that it meets the dimensional requirements after sintering. The specific molding process is as follows:

[0043] The process involves filling with powder, pressing, inserting a heating wire, filling with powder again, pressing again, and demolding to obtain a green aluminum nitride heating plate with an internal heating wire. The density of the green aluminum nitride heating plate is 1.8 g / cm³. 3 The heating wire is a 99.6% pure molybdenum wire;

[0044] S3: The aluminum nitride heating plate green blank is degummed in an air atmosphere degumming furnace. The degumming amount of the aluminum nitride heating plate green blank is 3.5%, the degumming temperature is 350℃, the heating rate is 0.5℃ / min, the high temperature holding time is 10 hours, and the cooling rate is 1.0℃ / min.

[0045] S4: Sintering is carried out using a graphite hot press furnace with a pressurization temperature of 1200℃, a pressurization pressure of 15MPa, a heating rate of 3℃ / min, a high temperature of 1700℃, a high temperature holding time of 4 hours, and a cooling rate of 0.5℃ / min.

[0046] By combining the liquid phase temperature point of aluminum nitride ceramic sintering and the temperature point of rapid grain development, the pressure during sintering is controlled, and the pressure temperature point is set at 1200℃. By using a suitable pressure temperature point, as much carbon as possible is discharged in the early stage of sintering, and the grain development and densification are completed before the carbon in the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon from the heating rod in the hot press furnace into the aluminum nitride ceramic body.

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

[0048] The aluminum nitride heating plate that has been sintered and removed from the furnace is cut into samples, and the location of the molybdenum wire is examined by scanning electron microscopy.

[0049] Example 3

[0050] A method for reducing corrosion of the heating wire in an aluminum nitride heating plate includes:

[0051] S1: Aluminum nitride granulated powder with added yttrium oxide was prepared by centrifugal spray granulation, wherein the proportion of yttrium oxide as a sintering aid was 5 wt%, the moisture content of the aluminum nitride granulated powder was 0.8%, and the bulk density was 1.5 g / cm³. 3 Particle size D50 = 90 μm;

[0052] S2: Forming the aluminum nitride heating plate preform using a dry pressing mold:

[0053] Based on the size of the heating plate, as well as the compression ratio and sintering shrinkage ratio of the powder, the thickness of each layer is controlled by filling with powder to ensure that it meets the dimensional requirements after sintering. The specific molding process is as follows:

[0054] The process involves filling with powder, pressing, inserting a heating wire, filling with powder again, pressing again, and demolding to obtain a green aluminum nitride heating plate with an internal heating wire. The density of the green aluminum nitride heating plate is 2.0 g / cm³. 3 The heating wire is a 99.7% pure molybdenum wire;

[0055] S3: The aluminum nitride heating plate green blank is degummed in an air atmosphere degumming furnace. The degumming amount of the aluminum nitride heating plate green blank is 5.5%, the degumming temperature is 450℃, the heating rate is 1.5℃ / min, the high temperature holding time is 14 hours, and the cooling rate is 3.0℃ / min.

[0056] S4: Sintering is carried out using a graphite hot press furnace with a pressurization temperature of 1500℃, a pressurization pressure of 35MPa, a heating rate of 5℃ / min, a high temperature of 1850℃, a high temperature holding time of 8 hours, and a cooling rate of 2℃ / min.

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

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

[0059] The aluminum nitride heating plate that has been sintered and removed from the furnace is cut into samples, and the location of the molybdenum wire is examined by scanning electron microscopy.

[0060] Example 4

[0061] Aluminum nitride heating plates were sintered using a graphite hot press furnace, with pressurization temperatures set at 1200℃, 1300℃, 1400℃, and 1500℃, and a pressurization pressure of 25MPa. The molybdenum wires at the above four different pressurization temperatures were examined by scanning electron microscopy to observe the corrosion on the surface of the molybdenum wires. The distribution of their room temperature thermal conductivity and heating wire resistance is shown in Table 1.

[0062] Table 1:

[0063] Serial Number Pressurization pressure / MPa Heating temperature point / ℃ Thermal conductivity at room temperature (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] As shown in Table 1, when the pressure is 25 MPa and the heating temperature is 1400 degrees Celsius, the maximum room temperature thermal conductivity is 195, and the heating wire resistance is 8 ohms.

[0065] Example 5

[0066] Aluminum nitride heating plates were sintered using a graphite hot press furnace. The pressurization temperature was set at 1300℃, and the pressurization pressure was set at 15MPa, 20MPa, 25MPa, and 30MPa. The molybdenum wires under different pressurization pressures were examined by scanning electron microscopy to observe the corrosion on the surface of the molybdenum wires. The distribution of their 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 / ℃ Thermal conductivity at room temperature (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 These are scanning electron microscope images of the molybdenum wire at different pressurization temperatures, namely 1200℃, 1300℃, 1400℃, and 1500℃. Figure 2 These are scanning electron microscope images of molybdenum wire at different pressures (15 MPa, 20 MPa, 25 MPa, and 30 MPa) according to the present invention. Figure 1 , Figure 2 Analysis of the various images shows that the higher the resistance of the molybdenum wire, the greater the corrosion. Figure 1 , Figure 2 The larger the loose area around the edges of an electron microscope image, the greater the corrosion. Figure 1 Among them, when the heating temperature is 1400 degrees Celsius, the frame pressure is 25 MPa, the room temperature thermal conductivity is the highest, and the corrosion of the molybdenum wire cross-section is small, making it the best choice.

[0070] The embodiments of the present invention have been 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 can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for reducing corrosion of the heating wire in an aluminum nitride heating plate, characterized in that, The method includes: S1: Aluminum nitride granulated powder with added yttrium oxide was prepared by centrifugal spray granulation, wherein the proportion of yttrium oxide as a sintering aid was 2-5 wt%; S2: Forming the aluminum nitride heating plate preform using a dry pressing mold: Based on the size of the heating plate, as well as the compression ratio and sintering shrinkage ratio of the powder, the thickness of each layer is controlled by filling with powder to ensure that it meets the dimensional requirements after sintering. The specific molding process is as follows: The process involves filling with powder, pressing, inserting a heating wire, filling with powder again, pressing again, and demolding to obtain a green aluminum nitride heating plate with an internal heating wire. The density of the green aluminum nitride heating plate is 1.8–2.0 g / cm³. 3 The heating wire is a molybdenum wire; S3: The aluminum nitride heating plate green blank is debonded in an air atmosphere debonding furnace, and the debonding amount of the aluminum nitride heating plate green blank is 3.5-5.5%; S4: Sintering is carried out using a graphite hot press furnace. The pressurization temperature is 1400℃, the pressurization pressure is 25MPa, the heating rate is 3~5℃ / min, the high temperature is 1700~1850℃, the high temperature holding time is 4~8 hours, and the cooling rate is 0.5~2℃ / min. By combining the liquid phase temperature point of aluminum nitride ceramic sintering and the temperature point of rapid grain development, and by controlling the pressure during sintering and the appropriate pressure temperature point, as much carbon as possible is discharged in the early stage of sintering, and the grain development and densification are completed before the carbon in the heating rod volatilizes in the middle stage of sintering, thereby reducing the diffusion of carbon from the heating rod in the hot press furnace into the aluminum nitride ceramic body. S5: Process the aluminum nitride heating plate after sintering and test the resistance of its built-in molybdenum wire; The aluminum nitride heating plate that has been sintered and removed from the furnace is cut into samples, and the location of the molybdenum wire is examined by scanning electron microscopy.

2. The method for reducing corrosion of the heating wire in an aluminum nitride heating plate according to claim 1, characterized in that, In step S1, the moisture content of the aluminum nitride granulated powder is <1%, and the loose packing density is 0.8–1.5 g / cm³. 3 The particle size of the powder is D50 = 70~90μm.

3. The method for reducing corrosion of the heating wire in an aluminum nitride heating plate according to claim 1, characterized in that, The heating wire in step S2 is a molybdenum wire with a purity of 99.5% or higher.

4. The method for reducing corrosion of the heating wire in an aluminum nitride heating plate according to claim 1, characterized in that, In step S3, when removing the binder from the aluminum nitride heating plate, the binder removal 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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