Aluminum nitride ceramic heating plate and preparation method thereof

Abstract

The invention relates to an aluminum nitride ceramic heating plate and a preparation method thereof, and the aluminum nitride ceramic heating plate comprises the following materials in parts by weight: 82-88 parts of aluminum nitride, 7-10 parts of titanium dioxide, 0.5-2 parts of magnesium oxide, 2-5.5 parts of silicon dioxide and 15-17 parts of a binder. By adopting an isostatic pressing process, the problem of strength of a green body is well solved; and the problems of cracking and deformation are solved by glue discharging and sintering processes.

Description

Technical Field

[0001] The invention specifically relates to an aluminum nitride ceramic heating plate and a preparation method thereof. Background Art

[0002] In recent years, the semiconductor industry has developed rapidly, and the number of ceramic parts required by its semiconductor equipment has increased day by day. The aluminum nitride ceramic heating chassis used in semiconductor manufacturing equipment is a major product of high-end aluminum nitride precision ceramics, which can be used in key core components of semiconductor equipment (PVD, CVD, ETCH, developer, etc.). The heating chassis is used as a wafer heater in the process chamber. It has extremely high requirements for product purity, high thermal conductivity and plasma impedance, and uniform heat distribution. The control requirements for a series of processes from powder preparation to ceramic molding sintering and post-processing are very demanding. The general molding method, such as dry pressing molding, has insufficient green body strength and microcracks, which leads to defects such as collapse and cracking during green body processing; due to the large size of the product, improper debinding and sintering processes lead to cracking and deformation of the product. After sintering, the product has a large porosity and is not dense; in addition, due to defects in the processing technology design during subsequent machining, it is also easy to cause white edges and collapse, which greatly reduces the yield of the product. Large-sized aluminum nitride ceramic materials are very expensive, and any slight problem in any detail will result in the material being scrapped, which is very risky. Summary of the invention

[0003] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is to provide an aluminum nitride ceramic heating plate.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is: an aluminum nitride ceramic heating plate, comprising the following materials in parts by weight: 82-88 parts of aluminum nitride, 7-10 parts of titanium dioxide, 0.5-2 parts of magnesium oxide, 2-5.5 parts of silicon dioxide and 15-17 parts of a binder.

[0005] Preferably, the binder comprises the following materials in parts by weight: 50-60 parts of paraffin, 20-30 parts of high-density polyethylene, 8-15 parts of polypropylene and 3-6 parts of stearic acid.

[0006] A method for preparing an aluminum nitride ceramic heating plate, using the aluminum nitride ceramic heating plate, comprises the following steps: (1) weighing aluminum nitride, titanium dioxide, silicon dioxide and magnesium oxide powders, mixing them evenly, and then grinding them to obtain a mixed powder; (2) transferring the mixed powder into an isostatic pressing machine for molding; (3) linearly cutting the molded green body into a plurality of aluminum nitride disc green bodies; (4) finely carving and trimming the aluminum nitride disc green bodies; (5) debinding the trimmed green disc green bodies; and (6) sintering the debinded green disc green bodies.

[0007] Preferably, the grinding specifically includes the following steps: mixing the weighed aluminum nitride, titanium dioxide, silicon dioxide and magnesium oxide powders evenly, then pre-burning the mixed powder at 900-1100°C for 3.5-6 hours, cooling it to room temperature with the furnace, and then grinding it to a particle size of 100-200 mesh to obtain a mixed powder.

[0008] Preferably, the isostatic pressing specifically includes the following steps: loading aluminum nitride granulated powder into an isostatic pressing mold, performing vibration filling through a vibration table, and after the powder filling is completed, installing a clamp and locking it, and then evacuating it, and then placing it in an isostatic press, and performing pressurization and pressing by a step-by-step pressure increase and pressure relief method.

[0009] Preferably, the debinding process specifically comprises the following steps: placing the trimmed green disc on a firing plate, placing it in a debinding furnace for debinding to remove the binder therein.

[0010] Preferably, the sintering specifically comprises the following steps: transferring the debinded green disc into a boron nitride crucible, placing it into a vacuum graphite furnace, and sintering it by filling it with nitrogen.

[0011] Compared with the prior art, the present invention has the following beneficial effects: the present invention solves the problem of green body strength by adopting isostatic pressing process; the debinding and sintering process solves the problem of cracking and deformation; in terms of processing, a complete set of processing schemes are designed, including the front and back processing procedures of the product, placement and clamping, and the processing grinding wheels, grinding rods and cutting tools used. Through this set of production processes, the aluminum nitride heating plate produced meets the requirements of semiconductor equipment, and a major breakthrough has been made in technology. DETAILED DESCRIPTION

[0013] An aluminum nitride ceramic heating plate comprises the following materials in parts by weight: 82 parts of aluminum nitride, 7 parts of titanium dioxide, 2 parts of magnesium oxide, 5 parts of silicon dioxide and 15 parts of a binder.

[0014] Preferably, the binder comprises the following materials in parts by weight: 55 parts of paraffin, 23 parts of high-density polyethylene, 10 parts of polypropylene and 6 parts of stearic acid.

[0015] A method for preparing an aluminum nitride ceramic heating plate, using the aluminum nitride ceramic heating plate, comprises the following steps: (1) weighing aluminum nitride, titanium dioxide, silicon dioxide and magnesium oxide powders, mixing them evenly, and then grinding them to obtain a mixed powder; (2) transferring the mixed powders into an isostatic pressing machine for molding; (3) linearly cutting the molded green body into a plurality of aluminum nitride disc green bodies, and cutting the isostatically pressed green body cylinder into a plurality of aluminum nitride disc green bodies of required thickness, at a linear speed of 40-60 mm / min; (4) finely carving and trimming the aluminum nitride disc green body, trimming the lower shape of the aluminum nitride disc green body with a green body fine carving machine, so that the shape of the aluminum nitride disc green body is relatively regular, at a rotation speed of 10000-12000 r / min, a feed of 600-800 mm, and a cutting depth of 0.3-0.5 mm; (5) debinding the trimmed green disc green body; and (6) sintering the debinded green disc green body.

[0016] In this embodiment, grinding specifically includes the following steps: mixing the weighed aluminum nitride, titanium dioxide, silicon dioxide and magnesium oxide powders evenly, then pre-burning the mixed powder at 900-1100°C for 3.5-6 hours, cooling it to room temperature with the furnace, and then grinding it to a particle size of 100-200 mesh to obtain a mixed powder.

[0017] In this embodiment, isostatic pressing specifically includes the following steps: loading aluminum nitride granulated powder into an isostatic pressing mold, vibrating and filling it through a vibration table, and after the powder filling is completed, installing a clamp and locking it, and then evacuating it, and then putting it into an isostatic press, and pressurizing and pressing it by a step-by-step pressure increase and pressure relief method.

[0018] Put the lower rubber sleeve into the outer support barrel, and then put it on the vibration table, slowly fill the lower rubber sleeve with 150KG aluminum nitride granulation powder, vibrate and fill, so that the powder is evenly distributed, put the upper rubber sleeve on after filling, wrap the lower rubber sleeve, add the clamp to lock, and then evacuate, after evacuating, put it into the isostatic press for pressurization, during the pressure increase process, first press 10MPa / min to 50MPa, hold the pressure for 5min, then press 7-8MPa / min to 100MPa, hold the pressure for 5min, and finally press 5MPa / min to 150MPa, hold the pressure for 10min, during the pressure relief process, first press 5MPa / min to 100MPa, then press 7-8MPa / min to 50MPa, and finally release the pressure naturally to obtain the aluminum nitride green cylinder. The aluminum nitride green cylinder is placed in an environment of 25-30℃ and 30-50% humidity for 24 hours to remove internal stress.

[0019] Lower rubber sleeve size: Φ530*800*3mm, upper rubber sleeve size: Φ520*150*3mm, outer support barrel size: Φ552*616*6mm.

[0020] A Φ150mm ejection hole is set at the bottom of the outer support barrel to facilitate demoulding and material removal.

[0021] In this embodiment, the debinding specifically includes the following steps: placing the trimmed green disc on a setter plate, placing it in a debinding furnace for debinding, and removing the binder therein. Applying 100 mesh aluminum nitride powder on the setter plate, and then placing the green disc on it, using a heating rate of 0.4°C / min at room temperature-120°C, a heating rate of 0.05°C / min at 120-300°C, a heating rate of 0.3°C / min at 300-400°C, and a heating rate of 0.5°C / min at 400-500°C, and keeping at 500°C for 6 hours.

[0022] In this embodiment, sintering specifically includes the following steps: transferring the debinded green disc into a boron nitride crucible, placing it into a vacuum graphite furnace, and sintering it by filling it with nitrogen.

[0023] Transfer the debinded aluminum nitride disc to a boron nitride crucible and cover it with a boron nitride pressing plate to ensure that the product has good flatness in the thickness direction during sintering and will not have significant deformation. The sintering furnace is a high-purity nitrogen atmosphere with a nitrogen pressure of 105KPa and a flow rate of 1.2-1.5L / min. The sintering temperature is set at 1750-1800℃. When sintering, the room temperature-600℃ adopts a heating rate of 5℃ / min, 600-1200℃ adopts a heating rate of 3℃ / min, and 1200-1600℃ adopts a heating rate of 2℃ / min. Keep warm at 1600℃ for 1 hour, and use a heating rate of 0.5℃ / min before 1600-1800℃. Keep warm at the highest temperature for 15-20 hours according to the thickness of the product.

[0024] It also includes machining: placing the sintered aluminum nitride disc blank on a surface grinder, fixing the blank with a magnetic block to prevent movement during machining, and using a 300-mesh diamond resin grinding wheel for plane machining at a speed of 2850r / min and a cutting depth of 0.01-0.02mm; using a smaller diameter disc for external cylindrical grinding, the diameter is about 10cm, and using yellow wax to heat and bond it to the large aluminum nitride disc to be machined. In this step, pay attention to the concentricity of the two discs, and then use a three-claw fixture to clamp the small disc for machining, and use a 300-mesh diamond resin grinding wheel for external cylindrical machining. The speed is 40r / min, and the wax is removed after heating after processing; drilling, grooving and threading are carried out by fine carving technology, and the aluminum nitride disc is fixed with sticky wax. The processing can be combined with electroplating and sintering grinding rod tools. The sintering grinding rod is used for rough processing and the electroplating grinding rod is used for fine processing. This can improve the processing efficiency. The speed is 18000-23000r / min, and the cutting depth is 0.01-0.02mm. In order to prevent white edges and chipping problems caused by drilling, grooving and threading, a certain amount of margin can be reserved for surface grinding. If the product allows, it can also be remedied by fine carving chamfering.

[0025] Performance test: The density of the heating plate reaches 3.35g / cm3, and the thermal conductivity reaches 200W / m*K.

[0026] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equalization change and modification made to the above embodiment by any technician familiar with the field without departing from the content of the technical solution of the present invention according to the technical essence of the present invention shall fall within the scope of the present invention.

Claims

1. An aluminum nitride ceramic heating plate, characterized in that: The invention comprises the following materials in parts by weight: 82-88 parts of aluminum nitride, 7-10 parts of titanium dioxide, 0.5-2 parts of magnesium oxide, 2-5.5 parts of silicon dioxide and 15-17 parts of a binder.

2. The aluminum nitride ceramic heating plate according to claim 1, characterized in that: The binder comprises the following materials in parts by weight: 50-60 parts of paraffin wax, 20-30 parts of high-density polyethylene, 8-15 parts of polypropylene and 3-6 parts of stearic acid.

3. A method for preparing an aluminum nitride ceramic heating plate, using the aluminum nitride ceramic heating plate according to claim 1, characterized in that: The method comprises the following steps: (1) weighing aluminum nitride, titanium dioxide, silicon dioxide and magnesium oxide powders, mixing them evenly, and then grinding them to obtain a mixed powder; (2) transferring the mixed powders into an isostatic pressing machine for forming; (3) cutting the formed green body into a plurality of aluminum nitride disc green bodies; (4) fine carving and trimming the aluminum nitride disc green bodies; (5) debinding the trimmed green disc green bodies; and (6) sintering the debinded green disc green bodies.

4. The method for preparing the aluminum nitride ceramic heating plate according to claim 1, characterized in that: Grinding specifically includes the following steps: The weighed aluminum nitride, titanium dioxide, silicon dioxide and magnesium oxide powders are mixed evenly, and then the mixed powder is pre-sintered at 900-1100°C for 3.5-6 hours, cooled to room temperature with the furnace, and then ground to a particle size of 100-200 mesh to obtain a mixed powder.

5. The method for preparing the aluminum nitride ceramic heating plate according to claim 1, characterized in that: The isostatic pressing process specifically includes the following steps: loading aluminum nitride granulated powder into an isostatic pressing mold, performing vibration filling through a vibration table, and after the powder filling is completed, installing a clamp and locking it, and then evacuating the mold, and then placing it in an isostatic press, and performing pressurization and pressing using a step-by-step pressure increase and pressure relief method.

6. The method for preparing the aluminum nitride ceramic heating plate according to claim 1, characterized in that: The debinding process specifically includes the following steps: placing the trimmed green disc on a firing plate, placing it in a debinding furnace for debinding to remove the binder therein.

7. The method for preparing the aluminum nitride ceramic heating plate according to claim 1, characterized in that: The sintering process specifically includes the following steps: transferring the debinded green disc into a boron nitride crucible, placing the crucible into a vacuum graphite furnace, and sintering the crucible by filling it with nitrogen.