Aluminum nitride ceramic heating plate and preparation method and application thereof

Abstract

The invention relates to an aluminum nitride ceramic heating plate and a preparation method and application thereof, and the preparation method comprises the following steps: mixing aluminum nitride powder and an auxiliary agent, and sequentially carrying out molding, hot pressed sintering and densification to obtain the aluminum nitride ceramic heating plate. The aluminum nitride powder is used as the raw material, the production steps are reduced, the production cost and the production difficulty are reduced, and the powder is used as the raw material, so that the uniformity of the aluminum nitride ceramic is improved, and the generation of microcracks in the ceramic is reduced. By adding the auxiliary agent, the uniformity and thermal conductivity of the aluminum nitride ceramic heating plate can be effectively regulated and controlled. The powder is used as a raw material, an aluminum nitride rough blank is prepared through hot pressed sintering, and the density of the aluminum nitride ceramic is further improved through densification. The prepared aluminum nitride ceramic heating plate is uniform in microstructure, free of layering, high in density, high in strength, uniform in heat conduction and not prone to cracking in the using process.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor parts and components, and in particular to a ceramic heating plate and a preparation method and application thereof, and in particular to an aluminum nitride ceramic heating plate and a preparation method and application thereof. Background Art

[0002] The heating plate is the main component of the chemical vapor deposition equipment, which is used to carry the wafer and adjust the temperature of the wafer. There is a heating element inside the heating plate, and the temperature of the surface of the heating plate can be adjusted by the heating element. There are two main types of heating plates currently used in the semiconductor industry: metal heating plates and ceramic heating plates. During the vapor deposition process, specific gases are introduced into the equipment cavity, and the metal heating plate may react with these gases and affect the coating on the surface of the wafer. Ceramic heating plates are increasingly used in chemical vapor deposition processes because of their stable chemical properties, which make them less likely to react chemically with gases, and they also have better electrical properties and thermal conductivity.

[0003] At present, the main material of ceramic heating plates is high-temperature ceramic materials such as aluminum nitride, aluminum oxide or silicon carbide. In order to ensure the flatness and parallelism of the ceramic heating plates during the packaging and molding process, multi-layer step-by-step hydraulic technology is often used. However, the uniformity, density and strength of the prepared ceramic heating plates are reduced, which leads to problems such as uneven heating of the wafer and deformation of the plate body, which can easily lead to abnormal coating.

[0004] CN110230043A discloses a chemical vapor deposition device, a ceramic heating plate and a method for preparing a ceramic heating plate, wherein a first aluminum nitride ceramic substrate, a heating plate, a second aluminum nitride ceramic substrate, an electrode plate and a third aluminum nitride ceramic substrate are sequentially bonded by ceramic slurry, and a heating plate is obtained by hot pressing and sintering. The ceramic heating plate prepared by this preparation method has good flatness and parallelism. However, the chemical composition, crystal phase composition and thermal and electrical properties of each layer of the prepared aluminum nitride ceramic heating plate are different, resulting in reduced uniformity, density and strength of the aluminum nitride ceramic heating plate, and then problems such as uneven heating of the wafer and deformation of the plate body occur, further causing coating abnormalities.

[0005] The existing technology has the problems of poor uniformity, low density and reduced strength of aluminum nitride ceramic heating plates. Therefore, how to reduce the processing difficulty, simplify the processing technology, and prepare aluminum nitride ceramic heating plates with uniform structure, high density and high strength has become a problem that needs to be solved urgently. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an aluminum nitride ceramic heating plate and a preparation method and application thereof. The present invention uses aluminum nitride powder as raw material, reduces production costs, reduces production steps, reduces production costs and production difficulties, and uses powder as raw material, which is beneficial to improving the uniformity of aluminum nitride ceramics and also beneficial to reducing the generation of microcracks inside ceramics. The present invention can effectively regulate the uniformity and thermal conductivity of the aluminum nitride ceramic heating plate by adding additives. The present invention uses powder as raw material, first hot presses and sinters and then densifies, prepares aluminum nitride rough blanks by hot presses and sinters, and then further improves the density of aluminum nitride ceramics by densification. The aluminum nitride ceramic heating plate prepared by the present invention has uniform microstructure without stratification, high density, high strength and uniform thermal conductivity, and is not easy to crack during use.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing an aluminum nitride ceramic heating plate, the preparation method comprising the following steps:

[0009] After the aluminum nitride powder and the auxiliary agent are mixed, molding, hot pressing sintering and densification are performed in sequence to obtain the ceramic heating plate.

[0010] The present invention uses aluminum nitride powder as raw material, reduces production costs, reduces production steps, reduces production costs and production difficulty, and uses powder as raw material, which is beneficial to improving the uniformity of aluminum nitride ceramics and also beneficial to reducing the generation of microcracks inside the ceramics. The present invention can effectively regulate the uniformity and thermal conductivity of the aluminum nitride ceramic heating plate by adding an auxiliary agent. The present invention uses powder as raw material, first hot presses and sinters and then densifies, prepares an aluminum nitride rough blank by hot press sintering, and then further improves the density of the aluminum nitride ceramic by densification. The aluminum nitride ceramic heating plate prepared by the present invention has a uniform microstructure without stratification, high density, high strength and uniform thermal conductivity, and is not easy to crack during use.

[0011] Preferably, the auxiliary agent comprises ethanol.

[0012] Preferably, based on the total mass of the aluminum nitride powder and the additive as 100%, the mass proportion of the additive is 3%-10%, for example, it can be 3%, 5%, 7%, 8%, 9% or 10%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0013] Preferably, the mixing method comprises ball milling.

[0014] Preferably, the ball-to-material ratio of the ball mill is (2-5):1, for example, 2:1, 3:1, 4:1, 4.5:1 or 5:1, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0015] Preferably, granulation is further performed after the mixing and before the molding.

[0016] Preferably, the granulation comprises spray granulation.

[0017] Preferably, the particle size D50 after granulation is 50 μm-200 μm, for example, 50 μm, 100 μm, 150 μm, 180 μm or 200 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the forming comprises cold press forming.

[0019] Preferably, the molding pressure is 20 MPa-50 MPa, for example, 20 MPa, 30 MPa, 40 MPa, 45 MPa or 50 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, after the forming and before the hot pressing and sintering, the outer shape processing is also performed to obtain a green body with a parallelism of 0.05mm-0.2mm on the upper and lower surfaces, wherein the parallelism can be 0.05mm, 0.1mm, 0.15mm, 0.18mm or 0.2mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the hot pressing sintering atmosphere is an inert gas atmosphere.

[0022] Preferably, the inert gas atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

[0023] Preferably, the hot pressing sintering includes one-stage sintering, two-stage sintering, three-stage sintering, four-stage sintering and five-stage sintering.

[0024] Preferably, the heating rate of the first stage sintering is 1°C / min-3°C / min, for example, it can be 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min or 3°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] Preferably, the insulation temperature of the first stage sintering is 100°C-250°C, for example, it can be 100°C, 150°C, 200°C, 220°C or 250°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the holding time of the sintering stage is 1 h-3 h, for example, 1 h, 1.5 h, 2 h, 2.5 h or 3 h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0027] Preferably, the heating rate of the second-stage sintering is 0.5°C / min-3°C / min, for example, it can be 0.5°C / min, 1°C / min, 1.5°C / min, 2°C / min, 2.5°C / min or 3°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, the holding temperature of the second-stage sintering is 400°C-600°C, for example, 400°C, 450°C, 500°C, 550°C or 600°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, the holding time of the second-stage sintering is 20h-30h, for example, it can be 20h, 22h, 24h, 26h, 28h or 30h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] Preferably, the heating rate of the three-stage sintering is 2°C / min-5°C / min, for example, it can be 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, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the holding temperature of the three-stage sintering is 900°C-1100°C, for example, it can be 900°C, 950°C, 1000°C, 1050°C or 1100°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] Preferably, the holding time of the three-stage sintering is 3h-5h, for example, 3h, 3.5h, 4h, 4.5h, 4.8h or 5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Preferably, pressurization is performed at the beginning of the three-stage sintering and heat preservation.

[0034] Said pressurization speed is 7.5MPa / h-17.5MPa / h, for example, it can be 7.5MPa / h, 10MPa / h, 12.5MPa / h, 15MPa / h or 17.5MPa / h, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0035] Preferably, the terminal pressure of the pressurization is 15 MPa-35 MPa, for example, it can be 15 MPa, 18 MPa, 20 MPa, 25 MPa, 30 MPa or 35 MPa, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, the heating rate of the four-stage sintering is 2°C / min-5°C / min, for example, it can be 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min or 5°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] Preferably, the insulation temperature of the four-stage sintering is 1300°C-1500°C, for example, it can be 1300°C, 1350°C, 1400°C, 1450°C or 1500°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0038] Preferably, the holding time of the four-stage sintering is 3h-5h, for example, 3h, 3.5h, 4h, 4.5h, 4.8h or 5h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0039] Preferably, the environmental pressure of the four-stage sintering is 15 MPa-35 MPa, for example, it can be 15 MPa, 18 MPa, 20 MPa, 25 MPa, 30 MPa or 35 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0040] Preferably, the heating rate of the five-stage sintering is 2°C / min-5°C / min, for example, it can be 2°C / min, 2.5°C / min, 3°C / min, 3.5°C / min, 4°C / min or 5°C / min, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0041] Preferably, the insulation temperature of the five-stage sintering is 1600°C-1750°C, for example, it can be 1600°C, 1650°C, 1700°C, 1720°C or 1750°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0042] Preferably, the holding time of the five-stage sintering is 5h-8h, for example, it can be 5h, 5.5h, 6h, 7h, 7.5h or 8h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] Preferably, the environmental pressure of the five-stage sintering is 15 MPa-35 MPa, for example, it can be 15 MPa, 18 MPa, 20 MPa, 25 MPa, 30 MPa or 35 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0044] The present invention improves the uniformity, thermal conductivity and compactness of aluminum nitride ceramics through five-stage sintering. Among them, regulating the insulation temperature and insulation time of the first stage sintering is conducive to removing water vapor in the raw material powder and preventing the aluminum nitride powder from being hydrolyzed at a higher temperature; regulating the insulation temperature and insulation time of the second stage sintering is conducive to removing organic matter in the additive and preventing the organic matter from remaining in the heating plate in the subsequent steps and affecting the thermal conductivity and strength of the heating plate; regulating the insulation temperature and insulation time of the third stage sintering to achieve pre-shrinkage of the heating plate, discharge gas in the raw material powder, and further improve the uniformity and compactness of the heating plate; regulating the insulation temperature and insulation time of the fourth stage sintering to increase the shrinkage rate of the heating plate and prevent the shrinkage rate from being too fast due to excessive temperature and affecting the compactness of the heating plate; regulating the insulation temperature and insulation time of the fifth stage sintering to provide a suitable temperature and time for uniform growth of grains, which is conducive to reducing structural defects inside the heating plate and improving the compactness and strength of the heating plate.

[0045] Preferably, after the hot pressing and sintering and before the densification, the shape is adjusted to obtain a green body with no pits or unevenness on the surface.

[0046] Preferably, the densification comprises hot isostatic pressing.

[0047] Preferably, the densification insulation temperature is 1700°C-1850°C, for example, it can be 1700°C, 1750°C, 1800°C, 1820°C or 1850°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0048] Preferably, the densification pressure is 120 MPa-160 MPa, for example, 120 MPa, 130 MPa, 140 MPa, 150 MPa or 160 MPa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0049] Preferably, the heat preservation and pressure holding time for densification is 5h-8h, for example, it can be 5h, 5.5h, 6h, 7h, 7.5h or 8h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] The present invention prepares aluminum nitride ceramics by densification, and further improves the density and uniformity of the aluminum nitride ceramics by reasonably controlling the temperature and time of densification. Within the preferred range of densification temperature and sintering time, not only can aluminum nitride ceramics with uniform composition, high density and high strength be obtained, but also the yield rate can be improved and the production cost can be reduced.

[0051] Preferably, after the densification, the outer shape trimming and sleeve welding are sequentially performed to obtain the aluminum nitride ceramic heating plate.

[0052] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0053] (1) Aluminum nitride powder and an additive are mixed by ball milling in proportion to obtain a mixed slurry, wherein the ball-to-material ratio of the ball milling is (2-5):1.

[0054] (2) The mixed slurry is granulated by a spray granulator to obtain a spherical mixed powder with a particle size D50 of 50 μm-200 μm.

[0055] (3) The spherical mixed powder and the heating wire are placed in a mold, and cold-pressed at a pressure of 20 MPa-50 MPa to obtain a molding material, which is then processed to obtain a green body with a parallelism of 0.05 mm to 0.2 mm between the upper and lower surfaces.

[0056] (4) After the green body is placed in a hot pressing furnace, an inert gas is injected to exhaust the air in the furnace, and then hot pressing and sintering are performed to obtain a green body after hot pressing and sintering, wherein the heating rate of the first stage sintering is 1°C / min-3°C / min, the holding temperature is 100°C-250°C, and the holding time is 1h-3h; the heating rate of the second stage sintering is 0.5°C / min-3°C / min, the holding temperature is 400°C-600°C, and the holding time is 20h-30h; the heating rate of the third stage sintering is 2°C / min-5°C / min, the holding temperature is 900°C-1100°C, and the holding time is 3h-5h. At the beginning of the third stage sintering and holding, heating is performed. pressure; the pressurization speed is 7.5MPa / h-17.5MPa / h, the terminal pressure is 15MPa-35MPa, the heating rate of the four-stage sintering is 2℃ / min-5℃ / min, the holding temperature is 1300℃-1500℃, the holding time is 3h-5h, and the ambient pressure is 15MPa-35MPa. The heating rate of the five-stage sintering is 2℃ / min-5℃ / min, the holding temperature is 1600℃-1750℃, the holding time is 5h-8h, and the ambient pressure is 15MPa-35MPa. After the holding time of the five-stage sintering is over, the heating is stopped, the pressure is maintained at 400℃, and then the pressure is released.

[0057] (5) The shape of the green body after hot pressing and sintering is adjusted, and then transferred to a hot isostatic pressing furnace for densification to obtain a densified green body, wherein the densification holding temperature is 1700° C.-1850° C., the pressure is 120 MPa-160 MPa, and the holding time is 5 h-8 h.

[0058] (6) The densified green body is subjected to shape trimming and sleeve welding in sequence to obtain the aluminum nitride ceramic heating plate.

[0059] In a second aspect, the present invention provides an aluminum nitride ceramic heating plate, which is prepared by the preparation method described in the first aspect.

[0060] In a third aspect, the present invention provides an application of the aluminum nitride ceramic heating plate as described in the second aspect, wherein the aluminum nitride ceramic heating plate is applied to chemical vapor deposition.

[0061] Compared with the prior art, the present invention has at least the following beneficial effects:

[0062] (1) The present invention uses aluminum nitride powder as raw material, reduces production steps, reduces production costs and production difficulty, and uses powder as raw material, which is beneficial to improving the uniformity of aluminum nitride ceramics and also helps to reduce the generation of microcracks inside the ceramics.

[0063] (2) The present invention can effectively control the uniformity and thermal conductivity of the aluminum nitride ceramic heating plate by adding additives.

[0064] (3) The present invention uses powder as raw material, first performs hot pressing and sintering and then performs densification, prepares aluminum nitride rough blank by hot pressing and sintering, and then further improves the density of aluminum nitride ceramic by densification.

[0065] (4) The aluminum nitride ceramic heating plate prepared by the present invention has a uniform microstructure without stratification, high density, high strength and uniform thermal conductivity, and is not easy to crack during use. DETAILED DESCRIPTION

[0066] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0067] Example 1

[0068] This embodiment provides a method for preparing an aluminum nitride ceramic heating plate, the method comprising the following steps:

[0069] (1) ball milling aluminum nitride powder and an additive to obtain a mixed slurry, wherein the ball-to-material ratio of the ball milling is 3:1, the weight proportion of the additive is 5%, and the additive is ethanol;

[0070] (2) the mixed slurry is granulated by a spray granulator to obtain a spherical mixed powder with a particle size D50 of 100 μm;

[0071] (3) The spherical mixed powder and the heating wire are placed in a mold, and cold-pressed at a pressure of 35 MPa to obtain a molding material, which is then processed to obtain a green body with a parallelism of 0.1 mm between the upper and lower surfaces;

[0072] (4) After the green body is placed in a hot pressing furnace, nitrogen is flushed into the furnace to exhaust the air, and then hot pressing and sintering are performed to obtain a green body after hot pressing and sintering. The heating rate of the first sintering is 2°C / min, the holding temperature is 200°C, and the holding time is 2h. The heating rate of the second sintering is 2°C / min, the holding temperature is 500°C, and the holding time is 25h. The heating rate of the third sintering is 3.5°C / min, the holding temperature is 1000°C, and the holding time is 4h. The third sintering and holding time start. The pressurization speed is 10MPa / h, the terminal pressure is 20MPa, the heating rate of the four-stage sintering is 3.5℃ / min, the holding temperature is 1400℃, the holding time is 4h, the ambient pressure is 20MPa, the heating rate of the five-stage sintering is 3.5℃ / min, the holding temperature is 1700℃, the holding time is 7.5h, the ambient pressure is 20MPa, after the holding time of the five-stage sintering is over, the heating is stopped, the pressure is maintained at 400℃, and the pressure is released;

[0073] (5) adjusting the shape of the green body after hot pressing and sintering, and then transferring it to a hot isostatic pressing furnace for densification to obtain a densified green body, wherein the densification holding temperature is 1800° C., the pressure is 140 MPa, and the holding time is 6.5 h;

[0074] (6) The densified green body is subjected to shape trimming and sleeve welding in sequence to obtain the aluminum nitride ceramic heating plate.

[0075] Example 2

[0076] This embodiment provides a method for preparing an aluminum nitride ceramic heating plate, the method comprising the following steps:

[0077] (1) ball milling aluminum nitride powder and an additive to obtain a mixed slurry, wherein the ball-to-material ratio of the ball milling is 2:1, the weight proportion of the additive is 10%, and the additive is ethanol;

[0078] (2) the mixed slurry is granulated by a spray granulator to obtain a spherical mixed powder with a particle size D50 of 200 μm;

[0079] (3) The spherical mixed powder and the heating wire are placed in a mold, and cold-pressed at a pressure of 50 MPa to obtain a molding material, which is then processed to obtain a green body with a parallelism of 0.05 mm between the upper and lower surfaces;

[0080] (4) After the green body is placed in a hot pressing furnace, argon gas is injected to exhaust the air in the furnace, and then hot pressing and sintering are performed to obtain a green body after hot pressing and sintering, wherein the heating rate of the first sintering is 1°C / min, the holding temperature is 100°C, and the holding time is 3h; the heating rate of the second sintering is 0.5°C / min, the holding temperature is 400°C, and the holding time is 30h; the heating rate of the third sintering is 2°C / min, the holding temperature is 900°C, and the holding time is 5h. The third sintering and holding time are Pressurization was performed at the beginning; the speed of pressurization was 7.5MPa / h, the final pressure was 15MPa, the heating rate of the four-stage sintering was 2℃ / min, the holding temperature was 1300℃, the holding time was 5h, the ambient pressure was 15MPa, the heating rate of the five-stage sintering was 2℃ / min, the holding temperature was 1600℃, the holding time was 8h, the ambient pressure was 15MPa, after the holding time of the five-stage sintering was over, the heating was stopped, the pressure was maintained at 400℃, and the pressure was released;

[0081] (5) adjusting the shape of the green body after hot pressing and sintering, and then transferring it to a hot isostatic pressing furnace for densification to obtain a densified green body, wherein the densification holding temperature is 1700° C., the pressure is 160 MPa, and the holding time is 8 h;

[0082] (6) The densified green body is subjected to shape trimming and sleeve welding in sequence to obtain the aluminum nitride ceramic heating plate.

[0083] Example 3

[0084] This embodiment provides a method for preparing an aluminum nitride ceramic heating plate, the method comprising the following steps:

[0085] (1) ball milling aluminum nitride powder and an additive to obtain a mixed slurry, wherein the ball-to-material ratio of the ball milling is 5:1, the weight proportion of the additive is 3%, and the additive is ethanol;

[0086] (2) the mixed slurry is granulated by a spray granulator to obtain a spherical mixed powder with a particle size D50 of 50 μm;

[0087] (3) The spherical mixed powder and the heating wire are placed in a mold, and cold-pressed at a pressure of 20 MPa to obtain a molding material, which is then processed to obtain a green body with a parallelism of 0.2 mm between the upper and lower surfaces;

[0088] (4) After the green body is placed in a hot pressing furnace, nitrogen is flushed into the furnace to exhaust the air in the furnace, and then hot pressing and sintering are performed to obtain a green body after hot pressing and sintering, wherein the heating rate of the first sintering is 3°C / min, the holding temperature is 250°C, and the holding time is 1h; the heating rate of the second sintering is 3°C / min, the holding temperature is 600°C, and the holding time is 20h; the heating rate of the third sintering is 5°C / min, the holding temperature is 1100°C, and the holding time is 3h. The holding time of the third sintering is The pressurization is carried out at the beginning; the speed of pressurization is 17.5MPa / h, the final pressure is 35MPa, the heating rate of the four-stage sintering is 5℃ / min, the holding temperature is 1500℃, the holding time is 3h, the ambient pressure is 35MPa, the heating rate of the five-stage sintering is 5℃ / min, the holding temperature is 1750℃, the holding time is 5h, the ambient pressure is 35MPa, after the holding time of the five-stage sintering is over, the heating is stopped, the pressure is maintained at 400℃, and the pressure is released;

[0089] (5) adjusting the shape of the green body after hot pressing and sintering, and then transferring it to a hot isostatic pressing furnace for densification to obtain a densified green body, wherein the densification holding temperature is 1850° C., the pressure is 120 MPa, and the holding time is 5 h;

[0090] (6) The densified green body is subjected to shape trimming and sleeve welding in sequence to obtain the aluminum nitride ceramic heating plate.

[0091] Example 4

[0092] The only difference between this embodiment and embodiment 1 is that, except for the temperature of the fourth stage sintering in step (4) being 1250° C., the rest is the same as embodiment 1.

[0093] Example 5

[0094] The only difference between this embodiment and embodiment 1 is that, except for the temperature of the fourth stage sintering in step (4) being 1550° C., the rest is the same as embodiment 1.

[0095] Example 6

[0096] The difference between this embodiment and embodiment 1 is that, except for the temperature of the fifth stage sintering in step (4) being 1550° C., the rest is the same as embodiment 1.

[0097] Example 7

[0098] The only difference between this embodiment and embodiment 1 is that, except for the temperature of the fifth stage sintering in step (4) being 1800° C., the rest is the same as embodiment 1.

[0099] Example 8

[0100] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the densification in step (5) is 1650° C., the rest is the same as embodiment 1.

[0101] Example 9

[0102] The only difference between this embodiment and embodiment 1 is that, except that the holding temperature of the densification in step (5) is 1900° C., the rest is the same as embodiment 1.

[0103] Example 10

[0104] The difference between this embodiment and embodiment 1 is that, except that the heat preservation and pressure holding time of densification in step (5) is 4.5 hours, the rest is the same as embodiment 1.

[0105] Embodiment 11

[0106] The difference between this embodiment and embodiment 1 is that, except that the heat preservation and pressure holding time of densification in step (5) is 8.5 hours, the rest is the same as embodiment 1.

[0107] Example 12

[0108] The difference between this embodiment and embodiment 1 is that except that the four-stage sintering in step (4) is not performed, the rest is the same as embodiment 1.

[0109] Embodiment 13

[0110] The difference between this embodiment and embodiment 1 is that except that the five-stage sintering in step (4) is not performed, the rest is the same as embodiment 1.

[0111] Comparative Example 1

[0112] The difference between this comparative example and Example 1 is that, except for not performing step (4), the rest is the same as Example 1.

[0113] Comparative Example 2

[0114] The difference between this comparative example and Example 1 is that, except for not performing step (5), the rest is the same as Example 1.

[0115] Comparative Example 3

[0116] This comparative example provides a method for preparing an aluminum nitride ceramic heating plate, the preparation method comprising the following steps:

[0117] (1) bonding the first aluminum nitride ceramic substrate, the heating plate, the second aluminum nitride ceramic substrate, the electrode plate and the third aluminum nitride ceramic substrate in order from bottom to top with aluminum nitride ceramic slurry to form a layer structure to obtain a green body;

[0118] (2) After the green body is placed in a hot pressing furnace, an inert gas is injected to exhaust the air in the furnace, and then hot pressing and sintering are performed to obtain a green body after hot pressing and sintering, wherein the heating rate of the first sintering is 2°C / min, the holding temperature is 200°C, and the holding time is 2h; the heating rate of the second sintering is 2°C / min, the holding temperature is 500°C, and the holding time is 25h; the heating rate of the third sintering is 3.5°C / min, the holding temperature is 1000°C, and the holding time is 4h. The holding time of the third sintering is 2.5°C / min, the holding temperature is 1000°C, and the holding time is 4h. Pressurization is performed at the beginning; the speed of pressurization is 10MPa / h, the final pressure is 20MPa, the heating rate of the four-stage sintering is 3.5℃ / min, the holding temperature is 1400℃, the holding time is 4h, the ambient pressure is 20MPa, the heating rate of the five-stage sintering is 3.5℃ / min, the holding temperature is 1700℃, the holding time is 7.5h, the ambient pressure is 20MPa, after the holding time of the five-stage sintering is over, the heating is stopped, the pressure is maintained at 400℃, and the pressure is released;

[0119] (3) adjusting the shape of the green body after hot pressing and sintering, and then transferring it to a hot isostatic pressing furnace for densification to obtain a densified green body, wherein the densification holding temperature is 1800° C., the pressure is 140 MPa, and the holding time is 6.5 h;

[0120] (4) The densified green body is subjected to shape trimming and sleeve welding in sequence to obtain the aluminum nitride ceramic heating plate.

[0121] Test Method

[0122] The actual density of the aluminum nitride ceramic heating plates prepared in Examples 1-13 and Comparative Examples 1-3 was measured by the water displacement method, and the density was calculated by comparing with the theoretical density and recorded in Table 1.

[0123] Table 1

[0124] Density Example 1 99.6％ Example 2 99.5％ Example 3 99.3％ Example 4 98.7％ Example 5 98.9％ Example 6 99.0％ Example 7 98.5％ Example 8 99.1％ Example 9 98.7％ Example 10 98.5％ Embodiment 11 99.0％ Example 12 98.3％ Embodiment 13 97.6％ Comparative Example 1 73％ Comparative Example 2 92％ Comparative Example 3 93.5%, but with stratification and uneven density

[0125] The test results show that:

[0126] (1) It can be seen from Examples 1-13 and Comparative Examples 1-3 that the present invention uses aluminum nitride powder as raw material, reduces production steps, reduces production costs and production difficulties, and uses powder as raw material, which is beneficial to improving the uniformity of aluminum nitride ceramics and reducing the generation of microcracks inside the ceramics. The present invention can effectively regulate the uniformity and thermal conductivity of the aluminum nitride ceramic heating plate by adding additives. The present invention uses powder as raw material, first hot presses and sinters and then densifies, prepares an aluminum nitride rough blank by hot press sintering, and then further improves the density of the aluminum nitride ceramic by densification. The aluminum nitride ceramic heating plate prepared by the present invention has a uniform microstructure without stratification, high density, high strength and uniform thermal conductivity, and is not easy to crack during use.

[0127] (2) It can be seen from Examples 1, 4-7 and 12-13 that the present invention further improves the density, strength and uniformity of the aluminum nitride ceramic heating plate by hot pressing and further limiting the temperature of the four-stage sintering and the five-stage sintering.

[0128] (3) It can be seen from Example 1 and Examples 8-11 that the present invention further improves the density, strength and uniformity of the aluminum nitride ceramic heating plate by further regulating the densification insulation temperature and insulation and pressure holding time.

[0129] In summary, the present invention uses aluminum nitride powder as raw material, reduces production steps, reduces production costs and production difficulty, and uses powder as raw material, which is beneficial to improving the uniformity of aluminum nitride ceramics and reducing the generation of microcracks inside ceramics. The present invention can effectively regulate the uniformity and thermal conductivity of the aluminum nitride ceramic heating plate by adding additives. The present invention uses powder as raw material, first hot pressing and sintering and then densification, and prepares aluminum nitride rough blanks by hot pressing and sintering, and then further improves the density of aluminum nitride ceramics by densification. The aluminum nitride ceramic heating plate prepared by the present invention has uniform microstructure without stratification, high density, high strength and uniform thermal conductivity, and is not easy to crack during use.

[0130] 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. A method for preparing an aluminum nitride ceramic heating plate, characterized in that: The preparation method comprises the following steps: After the aluminum nitride powder and the auxiliary agent are mixed, molding, hot pressing sintering and densification are performed in sequence to obtain the aluminum nitride ceramic heating plate.

2. The preparation method according to claim 1, characterized in that: The auxiliary agent includes ethanol; Preferably, based on the total mass of the aluminum nitride powder and the additive being 100%, the mass proportion of the additive is 3%-10%; Preferably, the mixing method comprises ball milling.

3. The preparation method according to claim 1 or 2, characterized in that: After the mixing and before the forming, granulation is also performed; Preferably, the particle size D50 after granulation is 50 μm-200 μm.

4. The preparation method according to any one of claims 1 to 3, characterized in that The forming includes cold press forming; Preferably, the molding pressure is 20MPa-50MPa.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The atmosphere of the hot pressing sintering is an inert gas atmosphere; Preferably, the hot pressing sintering includes one-stage sintering, two-stage sintering, three-stage sintering, four-stage sintering and five-stage sintering.

6. The preparation method according to claim 5, characterized in that: The holding temperature of the first stage sintering is 100°C-250°C; Preferably, the holding temperature of the second-stage sintering is 400°C-600°C; Preferably, the holding temperature of the three-stage sintering is 900°C-1100°C; Preferably, the three-stage sintering and heat preservation are pressurized at the beginning; Preferably, the terminal pressure of the pressurization is 15MPa-35MPa.

7. The preparation method according to claim 5 or 6, characterized in that: The holding temperature of the four-stage sintering is 1300° C.-1500° C.; Preferably, the environmental pressure of the four-stage sintering is 15MPa-35MPa; Preferably, the holding temperature of the five-stage sintering is 1600° C.-1750° C.; Preferably, the environmental pressure of the five-stage sintering is 15MPa-35MPa.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The densification comprises hot isostatic pressing; Preferably, the densification holding temperature is 1700°C-1850°C; Preferably, the densification pressure is 120MPa-160MPa; Preferably, the heat preservation and pressure holding time for densification is 5h-8h.

9. An aluminum nitride ceramic heating plate, characterized in that: The aluminum nitride ceramic heating plate is prepared by the preparation method described in any one of claims 1 to 8.

10. An application of the aluminum nitride ceramic heating plate as claimed in claim 9, characterized in that: The aluminum nitride ceramic heating plate is applied to chemical vapor deposition.