Aluminum nitride ceramic heater support body and preparation and welding method thereof

Abstract

The invention relates to an aluminum nitride ceramic heater support body and a preparation and welding method thereof. The aluminum nitride ceramic heater support body comprises a sintering aid-containing layering area and a sintering aid-free homogenizing area, the sintering aid-containing layering area is positioned at the lower end of the aluminum nitride ceramic heater support body; the sintering aid-containing layering area comprises the following components: aluminum nitride powder containing a sintering aid; the content of the sintering aid in the sintering aid-containing layering area is gradually reduced layer by layer from bottom to top; and the sintering aid-free uniform region comprises aluminum nitride powder. The lower end component of the aluminum nitride ceramic heater support body adopts a layered transition structure, so that the aluminum nitride ceramic heater support body is not easy to lose efficacy in a repeated heating and cooling process, and the service life is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic welding, and in particular to an aluminum nitride ceramic heater support and a preparation and welding method thereof. Background Art

[0002] With the rapid development of my country's semiconductor industry, the demand for the types and quantities of ceramic components is increasing, and the requirements for their quality are also getting higher and higher. Ceramic heaters are important components in equipment such as semiconductor thin film deposition. They can achieve uniform temperature distribution, uniformly heat the wafer, and enable high-precision reactions on the surface of the substrate to generate thin films. Usually, a ceramic heater includes a ceramic substrate with a wafer loading surface and a cylindrical support body that provides support on the back. In addition to a resistive heating circuit for heating, RF electrodes and electrodes for electrostatic chucks are also provided inside or on the surface of the ceramic substrate. Aluminum nitride ceramics have excellent thermal and mechanical properties and are the preferred material for ceramic components.

[0003] Pure aluminum nitride ceramics have poor thermoelectric properties due to the high oxygen content in the lattice. Therefore, the ceramic matrix used to support the wafer in aluminum nitride ceramic heaters usually adds oxide ceramics such as Y2O3, CaO, and Li2O to improve the thermoelectric performance. The thermoelectric performance of the support is not as high as that of the substrate. The use of low thermal conductivity materials for the support can also reduce the heat loss of the substrate. Pure aluminum nitride can be selected. The difference in the composition of the substrate and the support will cause differences in the thermal expansion coefficient, which will lead to cracking and other failures at the bonding interface during repeated heating and cooling. It is very important to ensure good wettability between the bonding layer and the ceramic and a low thermal expansion coefficient mismatch rate during the connection process of aluminum nitride ceramics.

[0004] Due to some inherent characteristics of ceramics, such as high chemical inertness, low diffusion rate, and high melting point, it is difficult to process large or complex-shaped parts, making ceramic connection a difficult technology, which has greatly restricted the development of ceramics. In addition, it is very important to ensure good wettability and low thermal expansion coefficient mismatch between the bonding layer and the ceramic during the ceramic connection process. The current ceramic connection technologies mainly include diffusion bonding, active brazing, liquid phase bonding, and glass solder bonding.

[0005] Invention CN 114012255 A discloses a method for welding ceramic materials, wherein the solder used comprises ceramic powder and light-curing resin, etc., and the solder is heated by laser or EB to achieve welding. Invention CN 115890058A discloses an Au-based composite solder of aluminum nitride ceramic, which is brazed at a temperature of 1080°C to 1200°C.

[0006] The support bodies of ceramic heaters prepared in the prior art are all single-component, which is different from the ceramic substrate that supports the wafer, and it is easy to fail at the welding point during repeated heating. Therefore, how to achieve welding of dissimilar ceramic materials and overcome the difference in expansion coefficients of dissimilar ceramic materials has become an urgent problem to be solved. Summary of the invention

[0007] In order to solve the above technical problems, the lower end component of the ceramic heater support prepared by the present invention adopts a layered transition structure, which solves the problem of welding failure during repeated heating.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides an aluminum nitride ceramic heater support body,

[0010] The aluminum nitride ceramic heater support body includes a layered area containing a sintering aid and a uniform area without a sintering aid;

[0011] The sintering aid-containing layered area is located at the lower end of the aluminum nitride ceramic heater support;

[0012] The composition of the sintering aid-containing layered zone is aluminum nitride powder containing a sintering aid;

[0013] The content of the sintering aid in the stratified area containing the sintering aid decreases from bottom to top;

[0014] The component of the uniform zone without sintering aid is aluminum nitride powder.

[0015] The present invention solves the technical problem of different thermal expansion coefficients of the aluminum nitride ceramic matrix and the support body by adopting a layered transition structure for the components at the lower end of the support body, thereby achieving the goal of not being prone to failure during repeated heating and cooling and extending the service life.

[0016] Preferably, the thickness of the sintering aid-containing layered area is 5 to 10 mm, for example, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

[0017] Preferably, the number of layers of the sintering aid-containing layered region is at least 2, for example, it may be 2, 3, 4, 5, 6, 7, 8, 9 or 10 layers.

[0018] Preferably, the sintering aid includes any one of oxides or fluorides of Si, Y, Ga, Na, Mg, Ca or Li metal, or a combination of at least two thereof.

[0019] Preferably, the minimum content of the sintering aid in the sintering aid-containing layered zone is 2 to 5wt%, for example, it can be 2wt%, 2.5wt%, 3wt%, 4wt% or 5wt%, etc., and the maximum content of the sintering aid is 8 to 10wt%, for example, it can be 8wt%, 8.5wt%, 9wt%, 9.5wt% or 10wt%, etc.

[0020] Preferably, the content of the sintering aid between two adjacent layers of the stratified area containing the sintering aid decreases by 1-2wt% from bottom to top, for example, it can be 1wt%, 1.2wt%, 1.4wt%, 1.6wt% or 2wt%.

[0021] The present invention controls the thickness of the stratified area containing the sintering aid within the range of 5 to 10 mm, the number of layers is at least 2, the minimum content of the sintering aid in the stratified area containing the sintering aid is 2 to 5wt%, and the maximum content of the sintering aid is within the range of 8 to 10wt%. The content of the sintering aid in the stratified area containing the sintering aid decreases by 1 to 2wt% layer by layer from bottom to top, thereby ensuring the transition effect of the composition and thermal expansion coefficient between the support body and the solder and the aluminum nitride ceramic matrix, and further extending the service life.

[0022] In a second aspect, the present invention provides a method for preparing the aluminum nitride ceramic heater support body according to the first aspect, the preparation method comprising the following steps:

[0023] Prepare a mold, first lay the raw material powder corresponding to the layered area containing sintering aid layer by layer, and then lay the raw material powder corresponding to the uniform area without sintering aid. After all the laying is completed, dry pressing and pressureless sintering are carried out in sequence to obtain the aluminum nitride ceramic heater support.

[0024] Preferably, the sintering temperature of the pressureless sintering is 1800-2000°C, for example, it can be 1800°C, 1850°C, 1900°C, 1950°C or 2000°C.

[0025] Preferably, the heating rate of the pressureless sintering is 2-5°C / min, for example, 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min, 4.5°C / min or 5°C / min.

[0026] Preferably, the holding time of the pressureless sintering is 2 to 4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours.

[0027] The present invention ensures the sintering effect of the support body by controlling the sintering temperature within the range of 1800-2000°C, the heating rate within the range of 2-5°C / min, and the heat preservation time within the range of 2-4h, and the sintering density of the support body can reach 100%.

[0028] In a third aspect, the present invention provides a welding method for an aluminum nitride ceramic heater support body, the welding method adopts the aluminum nitride ceramic heater support body described in the first aspect, and the method comprises the following steps:

[0029] (1) Pre-treating the welding surfaces of the aluminum nitride ceramic heater support and the ceramic substrate respectively;

[0030] (2) applying solder to the welding surface of the aluminum nitride ceramic heater support;

[0031] (3) Assembling the coated aluminum nitride ceramic heater support body and the pretreated ceramic substrate;

[0032] (4) The assembled product is hot pressed and sintered.

[0033] The present invention adopts a hot pressing method to realize the combination of the support body and the substrate at low temperature, so that the grain sizes of the substrate and the support body remain unchanged before and after the combination.

[0034] Preferably, the pretreatment comprises a rough grinding process.

[0035] Preferably, the surface roughness of the aluminum nitride ceramic substrate after the rough grinding is 1-3 μm, for example, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm.

[0036] Preferably, the pretreatment further comprises acid washing and pure water washing in sequence after the rough grinding.

[0037] Preferably, the solder comprises solid powder and liquid additives.

[0038] Preferably, the solid content of the solder is 30-40wt%, for example, 30wt%, 32wt%, 34wt%, 36wt%, 38wt% or 40wt%.

[0039] Preferably, the solid powder includes 20-50wt% of aluminum nitride powder, for example, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%.

[0040] The sintering aid may be 50-80wt%, for example, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt% or 80wt%.

[0041] Preferably, the particle size of the aluminum nitride powder is 0.5-3 μm, for example, 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm.

[0042] Preferably, the liquid additive includes 90-95wt% of solvent, for example, 90wt%, 91wt%, 92wt%, 93wt%, 94wt% or 95wt%; 2-5wt% of slow-drying agent, for example, 2%, 2.5%, 3%, 4% or 5%; 2-5wt% of oil-opening agent, for example, 2%, 2.5%, 3%, 4% or 5%.

[0043] Preferably, the solvent includes any one of anhydrous ethanol, isopropanol, and n-butanol, or a combination of at least two of them.

[0044] Preferably, there is no limitation on the ingredients of the slow-drying agent and the oil-opening agent, and any slow-drying agent and oil-opening agent known to those skilled in the art may be used.

[0045] Preferably, the material of the ceramic matrix is ​​aluminum nitride containing additives.

[0046] Preferably, the additive includes any one of oxides or fluorides of Si, Y, Ga, Na, Mg, Ca or Li metal, or a combination of at least two thereof.

[0047] Preferably, the additive and the sintering aid have the same composition.

[0048] The present invention preferably has the same composition of the additive in the ceramic matrix as the sintering aid in the solder and the sintering aid in the support, so as to play the role of transitioning the composition gap between the support and the ceramic matrix, avoiding the thermal stress gap caused by different materials during the heating and cooling process, so that the welded ceramic matrix and the support maintain good welding strength after multiple heating and cooling.

[0049] Preferably, the solder is prepared by ball milling mixing.

[0050] Preferably, the ball-to-material ratio of the ball milling mixture is 5:1 to 10:1, for example, it can be 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1.

[0051] Preferably, the ball milling time of the ball milling mixing is 12 to 48 hours, for example, it can be 12 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours or 48 hours.

[0052] The present invention adopts a ball milling method to prepare solder, controls the ball-to-solder ratio in the range of 5:1 to 10:1, controls the ball milling time in the range of 12 to 48 hours, makes the solder solid evenly dispersed in the liquid additive, and achieves a better welding effect.

[0053] Preferably, the coating uses a screen printing method.

[0054] Preferably, the sintering temperature is 1300-1500°C, for example, 1300°C, 1350°C, 1400°C, 1450°C or 1500°C.

[0055] Preferably, the heating rate of the hot pressing sintering is 3-10° C. / min.

[0056] Preferably, the holding time of the hot pressing sintering is 1 to 2 hours, for example, 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours or 2 hours.

[0057] Preferably, the hot pressing sintering is carried out for 3 to 10 hours when the temperature is raised to 300 to 600° C., for example, 3 hours, 4 hours, 5 hours, 6 hours, 8 hours or 10 hours.

[0058] The present invention preferably sets the hot pressing sintering temperature of welding sintering in the range of 1300-1500° C. to ensure a good sintering welding effect. When the temperature is raised to 300-600° C., the temperature is kept for 3-10 hours to fully volatilize the organic solvent in the solder.

[0059] As a preferred technical solution, the present invention provides a welding method for an aluminum nitride ceramic heater support, the method comprising the following steps:

[0060] (1) The welding surfaces of the aluminum nitride ceramic heater support and the ceramic substrate are respectively roughly ground to a surface roughness of 1 to 3 μm and then pickled and cleaned with pure water;

[0061] (2) The solder is coated on the welding surface of the aluminum nitride ceramic heater support by screen printing, wherein the solder includes solid powder and liquid additives, and the solid content is 30-40wt%, the solid powder includes 20-50wt% aluminum nitride powder, 50-80wt% sintering aid, the liquid additive includes 90-95wt% solvent, 2-5wt% slow drying agent, 2-5wt% oil opening agent, the solvent includes any one of anhydrous ethanol, isopropanol, and n-butanol or a combination of at least two, and the solder is prepared by ball milling for 12-48h at a ball-to-material ratio of 5:1-10:1;

[0062] (3) Assembling the coated aluminum nitride ceramic heater support body and the ceramic substrate;

[0063] (4) The assembled product is sintered in a hot pressing sintering furnace at a sintering temperature of 1300-1500°C for 1-2 hours and at a temperature of 300-600°C for 3-10 hours.

[0064] Compared with the prior art, the present invention has at least the following beneficial effects:

[0065] (1) The lower component of the ceramic heater support prepared by the present invention adopts a layered transition structure, which produces a transition in composition and thermal expansion coefficient with the solder and the substrate supporting the wafer, so that it is not easy to fail during repeated heating and cooling, thereby extending the service life.

[0066] (2) The substrate and the support are connected by hot pressing sintering. In the tensile strength test, the tensile strength of the weld is greater than the strength of the substrate itself. The ceramic heater substrate breaks, but the weld does not break. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is a process flow chart of the preparation and welding method of the aluminum nitride ceramic heater support provided in Preparation Example 1 and Example 1 of the present invention. DETAILED DESCRIPTION

[0068] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0069] Preparation Example 1

[0070] This preparation example provides a method for preparing an aluminum nitride ceramic heater support body, such as Figure 1 As shown, the preparation method comprises the following steps:

[0071] (1) The support body is formed by dry pressing, the thickness of the layered area containing the sintering aid at the lower end is 8 mm and is evenly divided into 6 layers, and the content of the yttrium oxide sintering aid decreases by 1wt% layer by layer from bottom to top, with the highest content being 10wt% and the lowest content being 5wt%.

[0072] (2) The support body after dry pressing is subjected to pressureless sintering at a sintering temperature of 1900°C, a heating rate of 3°C / min, and a holding time of 3h.

[0073] Preparation Example 2

[0074] This preparation example provides a method for preparing an aluminum nitride ceramic heater support, the preparation method comprising the following steps:

[0075] (1) The support body is formed by dry pressing, the thickness of the layered area containing the sintering aid at the lower end is 10 mm and is evenly divided into 4 layers, and the content of the yttrium oxide sintering aid decreases by 2wt% layer by layer from bottom to top, with the highest content being 8wt% and the lowest content being 2wt%.

[0076] (2) The support body after dry pressing is subjected to pressureless sintering at a sintering temperature of 1800°C, a heating rate of 2°C / min, and a holding time of 4h.

[0077] Preparation Example 3

[0078] This preparation example provides a method for preparing an aluminum nitride ceramic heater support, the preparation method comprising the following steps:

[0079] (1) The support body is formed by dry pressing, the thickness of the layered area containing the sintering aid at the lower end is 5 mm and is divided into two layers, and the content of the yttrium oxide sintering aid decreases by 1.5wt% layer by layer from bottom to top, with the highest content being 8wt% and the lowest content being 5wt%.

[0080] (2) The support body after dry pressing is subjected to pressureless sintering at a sintering temperature of 2000°C, a heating rate of 5°C / min, and a holding time of 2h.

[0081] Preparation Example 4

[0082] In this preparation example, except that the thickness of the layered area containing the sintering aid is 4 mm, other conditions are the same as those in Preparation Example 1.

[0083] Preparation Example 5

[0084] In this preparation example, except that the thickness of the layered area containing the sintering aid is 11 mm, other conditions are the same as those in Preparation Example 1.

[0085] Preparation Example 6

[0086] In this preparation example, except that the minimum content of the yttrium oxide sintering aid in the sintering aid layered zone is 1wt% and the maximum content of the yttrium oxide sintering aid is 6wt%, other conditions are the same as those in Preparation Example 1.

[0087] Preparation Example 7

[0088] In this preparation example, except that the yttrium oxide sintering aid content in the sintering aid layered zone is as low as 20wt% and as high as 25wt%, other conditions are the same as those in preparation example 1.

[0089] Preparation Comparative Example 1

[0090] In this comparative preparation example, no sintering aid-containing layered region is set, the support material is all aluminum nitride, and other conditions are the same as those in Preparation Example 1.

[0091] Example 1

[0092] This embodiment provides a welding method for an aluminum nitride ceramic heater support body, wherein the support body is the support body prepared in Preparation Example 1. Figure 1 As shown, the method comprises the following steps:

[0093] (1) The weld surface is roughly ground to a surface roughness of 2 μm and then pickled and cleaned with pure water;

[0094] (2) coating the solder on the welding surface of the support by screen printing; wherein the solder comprises 18 wt% of aluminum nitride powder, 17 wt% of yttrium oxide sintering aid, 58 wt% of solvent, 2 wt% of slow drying agent and 5 wt% of oil opening agent; and the solder is prepared by ball milling for 24 hours at a ball-to-material ratio of 8:1;

[0095] (3) Assembling the coated support body with a ceramic substrate, wherein the material of the ceramic substrate is aluminum nitride with 20 wt% yttrium oxide added;

[0096] (4) The assembled product is sintered in a hot pressing sintering furnace at a sintering temperature of 1400°C for 2 hours, and then kept at 400°C for 5 hours.

[0097] Example 2

[0098] This embodiment provides a welding method for an aluminum nitride ceramic heater support body, wherein the support body is the support body prepared in Preparation Example 2, and the method comprises the following steps:

[0099] (1) The weld surface is roughly ground to a surface roughness of 1 μm and then pickled and cleaned with pure water;

[0100] (2) coating the solder on the welding surface of the support by screen printing, wherein the solder comprises 15 wt% of aluminum nitride powder, 20 wt% of yttrium oxide sintering aid, 56 wt% of solvent, 4 wt% of slow drying agent and 5 wt% of oil opening agent; and preparing the solder by ball milling for 12 h at a ball-to-material ratio of 10:1;

[0101] (3) Assembling the coated support body with a ceramic substrate, wherein the material of the ceramic substrate is aluminum nitride with 20 wt% yttrium oxide added;

[0102] (4) The assembled product is sintered in a hot pressing sintering furnace at a sintering temperature of 1300°C for 1 hour, and then kept at 600°C for 10 hours.

[0103] Example 3

[0104] This embodiment provides a welding method for an aluminum nitride ceramic heater support body, wherein the support body is the support body prepared in Preparation Example 3, and the method comprises the following steps:

[0105] (1) The weld surface is roughly ground to a surface roughness of 3 μm and then pickled and cleaned with pure water;

[0106] (2) coating the solder on the welding surface of the support by screen printing, wherein the solder comprises 8 wt% of aluminum nitride powder, 32 wt% of yttrium oxide sintering aid, 54 wt% of solvent, 2 wt% of slow drying agent and 4 wt% of oil opening agent; and preparing the solder by ball milling for 48 h at a ball-to-material ratio of 5:1;

[0107] (3) Assembling the coated support body with a ceramic substrate, wherein the material of the ceramic substrate is aluminum nitride with 20 wt% yttrium oxide added;

[0108] (4) The assembled product is sintered in a hot pressing sintering furnace at a sintering temperature of 1500°C for 1.5 h. When the temperature is raised to 300°C, the temperature is kept for 40 min.

[0109] Example 4

[0110] Except that the sintering temperature is 1200° C., other conditions of this embodiment are the same as those of embodiment 1.

[0111] Example 5

[0112] Except that the sintering temperature is 1600° C., other conditions of this embodiment are the same as those of embodiment 1.

[0113] Example 6

[0114] Except that the heat preservation stage is not provided in the low temperature section during sintering, other conditions in this embodiment are the same as those in Embodiment 1.

[0115] Example 7

[0116] Except that the sintering holding time is 0.5 h, other conditions in this embodiment are the same as those in embodiment 1.

[0117] Example 8

[0118] Except that the sintering holding time is 2.5 h, other conditions in this embodiment are the same as those in embodiment 1.

[0119] Example 9

[0120] Except for using the aluminum nitride ceramic heater support body prepared in Preparation Example 4, other conditions in this embodiment are the same as those in Example 1.

[0121] Example 10

[0122] Except for using the aluminum nitride ceramic heater support body prepared in Preparation Example 5, other conditions in this embodiment are the same as those in Example 1.

[0123] Embodiment 11

[0124] Except for using the aluminum nitride ceramic heater support body prepared in Preparation Example 6, other conditions in this embodiment are the same as those in Example 1.

[0125] Example 12

[0126] Except for using the aluminum nitride ceramic heater support body prepared in Preparation Example 7, other conditions in this embodiment are the same as those in Example 1.

[0127] Comparative Example 1

[0128] Except for using the aluminum nitride ceramic heater support body prepared in Comparative Example 1, other conditions in this comparative example are the same as those in Example 1.

[0129] Test method: After the soldered device is repeatedly heated and cooled 10 times, a tensile test is performed on a tensile testing machine, and the position of the fracture is recorded. The specific test results are shown in Table 1.

[0130] Table 1

[0131]

[0132]

[0133] The test results show that:

[0134] (1) It can be seen from Examples 1 to 3 that the present invention adopts a layered transition structure through the composition of the lower end of the ceramic heater support body, which produces a transition in composition and thermal expansion coefficient with the solder and the substrate supporting the wafer, and adopts hot pressing sintering to weld the support body to achieve the goal of not being prone to failure during repeated heating and cooling, thereby extending the service life, and the welding strength can reach a strength at the welding point that is not less than the strength of the substrate, and in the tensile test, the welding part remains intact after the substrate breaks.

[0135] (2) It can be seen from Examples 1 and 4 to 8 that the present invention can achieve better welding strength and longer service life by further optimizing welding conditions. If the sintering temperature is too low, the density is low, and if the sintering temperature is too high, the grain growth is out of control and the potential cracking possibility increases. In addition, it is preferred to set a holding time in the low-temperature sintering stage to allow the liquid solvent component to fully volatilize. When the holding stage is not set, the weld cracks in the tensile test. The sintering holding time is further optimized. When the holding time is too short, the sintering density decreases, causing the weld tensile strength to decrease and the weld cracks.

[0136] (3) It can be seen from Examples 1 and 9 to 12 that the present invention improves the stress transition effect of the support body by further optimizing the thickness of the sintering aid-containing layered area and the sintering aid content of the support body. If the thickness of the sintering aid-containing layered area is too low and the content of the sintering aid-containing layered area is too high or too low, it will cause poor stress transition effect of the support body and fracture at the weld during the tensile test.

[0137] (4) It can be seen from Example 1 and Comparative Example 1 that the present invention prepares a lower-end layered transition structure support body by dry pressing followed by pressureless sintering, and the content of the sintering aid gradually decreases from bottom to top to form a transition layer between the solder layer and the support body, thereby improving the phenomenon of excessive difference in thermal expansion coefficient caused by component difference and repeated heating and cooling leading to welding failure. When a support material with uniform composition is used, the transition stress cannot be played, the welding tensile strength drops sharply, and fracture occurs at the welding point.

[0138] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. An aluminum nitride ceramic heater support, characterized in that: The aluminum nitride ceramic heater support body includes a layered area containing a sintering aid and a uniform area without a sintering aid; The sintering aid-containing layered area is located at the lower end of the aluminum nitride ceramic heater support; The composition of the sintering aid-containing layered region includes aluminum nitride powder containing a sintering aid; The content of the sintering aid in the stratified area containing the sintering aid decreases layer by layer from bottom to top; The composition of the uniform zone free of sintering aids includes aluminum nitride powder.

2. The aluminum nitride ceramic heater support according to claim 1, characterized in that: The thickness of the sintering aid-containing layered area is 5 to 10 mm; Preferably, the number of layers of the sintering aid-containing layered region is at least 2; Preferably, the sintering aid comprises any one or a combination of at least two of oxides or fluorides of Si, Y, Ga, Na, Mg, Ca or Li metals; Preferably, the minimum content of the sintering aid in the stratified region containing the sintering aid is 2-5wt%, and the maximum content of the sintering aid is 8-10wt%; Preferably, the content of the sintering aid in the stratified regions containing the sintering aid decreases by 1 to 2 wt % layer by layer from bottom to top.

3. A method for preparing the aluminum nitride ceramic heater support as claimed in claim 1 or 2, characterized in that: The preparation method comprises the following steps: Prepare a mold, first lay the raw material powder corresponding to the layered area containing sintering aid layer by layer, and then lay the raw material powder corresponding to the uniform area without sintering aid. After all the laying is completed, dry pressing and pressureless sintering are carried out in sequence to obtain the aluminum nitride ceramic heater support.

4. The preparation method according to claim 3, characterized in that: The sintering temperature of the pressureless sintering is 1800-2000°C; Preferably, the heating rate of the pressureless sintering is 2 to 5°C / min; Preferably, the holding time of the pressureless sintering is 2 to 4 hours.

5. A welding method for an aluminum nitride ceramic heater support, characterized in that: The welding method adopts the aluminum nitride ceramic heater support according to claim 1 or 2, and the method comprises the following steps: (1) Pre-treating the welding surfaces of the aluminum nitride ceramic heater support and the ceramic substrate respectively; (2) applying solder to the welding surface of the aluminum nitride ceramic heater support; (3) Assembling the coated aluminum nitride ceramic heater support body and the pretreated ceramic substrate; (4) The assembled product is hot pressed and sintered.

6. The welding method according to claim 5, characterized in that: The pretreatment in step (1) includes rough grinding; Preferably, the surface roughness of the welding surface after the rough grinding is 1 to 3 μm: Preferably, the pretreatment further comprises acid washing and pure water washing in sequence after the rough grinding.

7. The welding method according to claim 5 or 6, characterized in that: The solder in step (2) comprises solid powder and liquid additives; Preferably, the solid content of the solder is 30-40wt%; Preferably, the solid powder comprises 20-50wt% aluminum nitride powder and 50-80wt% sintering aid; Preferably, the particle size of the aluminum nitride powder is 0.5 to 3 μm; Preferably, the liquid additive comprises 90-95wt% of solvent, 2-5wt% of slow-drying agent, and 2-5wt% of oil-opening agent; Preferably, the solvent includes any one of anhydrous ethanol, isopropanol, and n-butanol, or a combination of at least two of them.

8. The welding method according to any one of claims 5 to 7, characterized in that: The solder in step (2) is prepared by ball milling mixing; Preferably, the ball-to-material ratio of the ball milling mixture is 5:1 to 10:1; Preferably, the ball milling time of the ball milling mixing is 12 to 48 hours; Preferably, the coating in step (2) is performed using a screen printing method.

9. The welding method according to any one of claims 5 to 8, characterized in that: The sintering temperature of the hot pressing sintering in step (4) is 1300-1500° C. Preferably, the heating rate of the hot pressing sintering is 3 to 10°C / min; Preferably, the holding time of the hot pressing sintering is 1 to 2 hours; Preferably, the hot pressing sintering is carried out by heating the temperature to 300-600° C. and keeping the temperature for 3-10 hours.

10. The welding method according to any one of claims 5 to 9, characterized in that: The method comprises the following steps: (1) The welding surfaces of the aluminum nitride ceramic heater support and the ceramic substrate are respectively roughly ground to a surface roughness of 1 to 3 μm and then pickled and cleaned with pure water in sequence; (2) The solder is coated on the welding surface of the aluminum nitride ceramic heater support by screen printing, wherein the solder includes solid powder and liquid additives, and the solid content is 30-40wt%, the solid powder includes 20-50wt% aluminum nitride powder, 50-80wt% sintering aid, the liquid additive includes 90-95wt% solvent, 2-5wt% slow drying agent, 2-5wt% oil opening agent, the solvent includes any one of anhydrous ethanol, isopropanol, and n-butanol or a combination of at least two, and the solder is prepared by ball milling for 12-48h at a ball-to-material ratio of 5:1-10:1; (3) Assembling the coated aluminum nitride ceramic heater support body and the ceramic substrate; (4) The assembled product is sintered in a hot pressing sintering furnace at a sintering temperature of 1300-1500°C for 1-2 hours and at a temperature of 300-600°C for 3-10 hours.

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