Preparation method of large-size aluminum nitride ceramic rod

Abstract

The invention discloses a preparation method of a large-size aluminum nitride ceramic rod, and belongs to the technical field of electrostatic chucks, the method comprises the steps that S1, a rubber mold is customized according to the aluminum nitride ceramic rod, and the rubber mold comprises a rubber mold body with an inner cavity and a rubber plug; s2, placing the customized rubber mold body on a vibration platform, carrying out vibration filling, plugging with a rubber plug after filling, and sealing; s3, performing pressing after sealing; s4, the pressed green bodies are placed on a customized BN stacking supporting base, the BN stacking supporting base comprises a V-shaped jig, an upper cover plate located above the V-shaped jig, a front side plate and a rear side plate, the front side plate and the rear side plate are located on the front portion and the rear portion of the V-shaped jig, the green bodies are stacked on the V-shaped jig, BN powder is scattered on the green bodies during stacking, adhesion is prevented, and the green bodies are placed on the V-shaped jig; wherein through holes are uniformly distributed in the V-shaped jig, the upper cover plate, the front side plate and the rear side plate; s5, splicing the stacked blanks into a front side plate and a rear side plate by using BN plates, and buckling an upper cover plate; and S6, the BN stacking supporting base is fed into an atmosphere furnace to be sintered.

Description

Technical Field

[0001] The invention relates to the technical field of electrostatic chucks, and in particular to a method for preparing a large-size aluminum nitride ceramic rod. Background Art

[0002] In the manufacturing process of semiconductor equipment, such as electrostatic chucks, the molding and sintering of large-size ceramic rods are the key to preparation. In the past, molding methods were all achieved through wet molding, such as injection, hot pouring and the like. Due to the addition of certain additives and plasticizers during the molding process, uneven doping during the mixing process and unvolatile residues during the debinding process will have a certain impact on product performance during the sintering process. Isostatic pressing can completely avoid the defects caused by wet molding, but because AIN is easy to hydrolyze, moisture control during the molding process is the key. Once water enters the mold, the sample will be scrapped. The powder granulated under constant temperature and humidity is placed in a customized rubber mold for vibration filling and sealing, and isostatic pressing is performed under a pressure of 150MPa. Since the mold design is close to the net size, the machining process can be avoided.

[0003] For green bodies with a relatively large length-to-diameter ratio, burying is generally used to prevent the green body from sintering deformation. Since the buried materials are naturally stacked and have a loose structure, they are easy to cause green body deformation during sintering. At the same time, a large amount of buried materials will absorb a certain amount of heat, and the thermal conductivity temperature gradient is large, resulting in stress, which leads to the destruction of the green body shape. Although hanging sintering can adjust the verticality by its own weight, the green body lacks protection. However, due to the high AIN sintering temperature, it must pass through the graphite heating element to reach the set temperature. At high temperatures, the C element of the graphite body volatilizes and changes the furnace atmosphere, which will cause the product to be scrapped. Although sleeve sintering (inside the sagger) can change the sintering performance of the green body, the stacking of sleeves is easy to cause a large temperature gradient and large deformation of the green body in the upper and lower sleeves. The thickness of the green body must be increased to reduce the large deformation caused by the large temperature gradient, but it will result in more complex machining, high cost and energy consumption, which is not conducive to production. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a large-sized aluminum nitride ceramic rod to solve the problem raised in the background technology.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A method for preparing a large-size aluminum nitride ceramic rod, the method comprising:

[0007] S1: A corresponding rubber mold is customized according to the specific size of the large-sized aluminum nitride ceramic rod, wherein the rubber mold includes a rubber mold body having an inner cavity and a rubber plug matched with the rubber mold body;

[0008] S2: Place the customized rubber mold on a vibration platform, set the vibration frequency of the vibration platform to 30-33 Hz and the amplitude to 0.5-0.8 mm, and vibrate and fill the aluminum nitride powder. After the aluminum nitride powder is filled, insert the rubber plug into the rubber mold body and seal it to prevent moisture from entering.

[0009] S3: After sealing, the sealed green body is pressed by cold isostatic pressing at a pressure of 200 MPa to form an aluminum nitride ceramic rod green body;

[0010] S4: placing the pressed aluminum nitride ceramic rod green body on a customized BN stacking support seat, wherein the BN stacking support seat comprises a V-shaped fixture, an upper cover plate located above the V-shaped fixture, and a front side plate and a rear side plate located before and after the V-shaped fixture, and the green body is stacked on the V-shaped fixture. BN powder is sprinkled on the green body to prevent adhesion during stacking, wherein the V-shaped fixture, the upper cover plate, the front side plate, and the rear side plate are evenly covered with through holes, and support rods are provided on the left and right sides of the V-shaped fixture;

[0011] S5: Use BN plates to splice the front and rear side plates of the stacked blanks, and then tighten and buckle the upper cover plate with BN fastening screws;

[0012] S6: Send the BN stacking support into the atmosphere furnace, heat it to 1850℃ in N2 atmosphere and keep it for 3h for sintering, and cool it down naturally after sintering;

[0013] S7: After cooling, the radial deviation of the cooked dough is tested to verify whether the preparation process has fully achieved the expected effect.

[0014] Preferably, the aluminum nitride ceramic rod is a cylindrical rod, the diameter of the inner cavity of the rubber mold body is equal to the diameter of the aluminum nitride ceramic rod, and the depth of the inner cavity of the rubber mold body is equal to the length of the aluminum nitride ceramic rod.

[0015] Preferably, in step S2, the vibration frequency of the vibration platform is 32 Hz and the amplitude is 0.7 mm.

[0016] Preferably, in step S4, when the pressed green billets are placed on the customized BN stacking support, an aluminum nitride ceramic rod green billet is placed at the lowest position of the V-shaped fixture as the first layer, two aluminum nitride ceramic rod green billets are placed on the first layer as the second layer, three aluminum nitride ceramic rod green billets are placed on the second layer as the third layer, and so on until the required number of layers are placed.

[0017] Preferably, the two aluminum nitride ceramic rod green sheets on the second layer are symmetrically arranged with respect to the aluminum nitride ceramic rod green sheets on the first layer, and the two aluminum nitride ceramic rod green sheets on the second layer are flush in the left-right direction.

[0018] The above technical solution has the following beneficial effects:

[0019] The aluminum nitride ceramic rod green body is prepared by the method described in the present application, which can ensure the yield and improve the production efficiency.

[0020] The evenly punched holes on both sides of the V-shaped fixture can ensure sufficient heat exchange of the hot air flow and ensure uniform shrinkage and flatness of the aluminum nitride ceramic rod green body;

[0021] The gravity of the aluminum nitride ceramic rod green body can be balanced by the supporting forces on both sides, thereby reducing the pressure of gravity on the lower green body and maintaining deformation. Multiple aluminum nitride ceramic rods can be sintered at one time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the three-dimensional structure of the aluminum nitride ceramic rod green body and the V-shaped fixture of the present invention;

[0023] Figure 2 It is a schematic diagram of the structure of the aluminum nitride ceramic rod green body and the V-shaped fixture of the present invention;

[0024] Figure 3 It is a structural schematic diagram of the BN stacking support base of the present invention. DETAILED DESCRIPTION

[0025] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] A method for preparing a large-size aluminum nitride ceramic rod, the preparation method comprising:

[0027] S1: According to the specific size of the large-sized aluminum nitride ceramic rod, a corresponding rubber mold is customized, the rubber mold includes a rubber mold body with an inner cavity and a rubber plug matched with the rubber mold body, the length of the large-sized aluminum nitride ceramic rod is larger than that of the large-sized aluminum nitride ceramic rod, the outer diameter of the large-sized aluminum nitride ceramic rod is equal to the diameter of the inner cavity of the rubber mold body, and the length is also equal, and the large-sized aluminum nitride ceramic rod green body 3 is formed after being pressed by the corresponding rubber mold;

[0028] S2: Place the customized rubber mold on a vibration platform, set the vibration frequency of the vibration platform to 30-33 Hz and the amplitude to 0.5-0.8 mm, and vibrate and fill the aluminum nitride powder. After the aluminum nitride powder is filled, insert the rubber plug into the rubber mold body and seal it to prevent moisture from entering. After vibration filling, the aluminum nitride powder can be initially formed into a green body;

[0029] S3: After sealing, the sealed green body is pressed by cold isostatic pressing at a pressure of 200 MPa to form an aluminum nitride ceramic rod green body 3, and then isostatic pressing is performed after vibration canning to form an aluminum nitride ceramic rod green body 3;

[0030] S4: Place the pressed aluminum nitride ceramic rod green body 3 on the customized BN stacking support seat, refer to Figure 1 to Figure 3 The BN stacking support seats are all made of BN material, BN is boron nitride, and the BN stacking support seat includes a V-shaped fixture 1, an upper cover plate 5 located above the V-shaped fixture 1, and a front side plate 4 and a rear side plate located before and after the V-shaped fixture 1. The aluminum nitride ceramic rod green body 3 is stacked on the V-shaped fixture 1. When stacking, BN powder is sprinkled on the aluminum nitride ceramic rod green body 3 to prevent adhesion. The V-shaped fixture 1, the upper cover plate 5, the front side plate 4, and the rear side plate are evenly covered with through holes. The evenly distributed through holes can be used for hot air flow exchange to ensure that each aluminum nitride ceramic rod green body 3 is evenly heated and contracted to ensure its verticality. Support rods 2 are provided on the left and right sides of the V-shaped fixture 1. The support rods 2 are used to support the V-shaped fixture 1 to ensure the stability of the entire BN stacking support seat;

[0031] The BN stacking support seat is used to place multiple aluminum nitride ceramic rod green sheets 3. The multiple aluminum nitride ceramic rod green sheets 3 are specifically placed on a V-shaped fixture. An aluminum nitride ceramic rod green sheet 3 is placed at the bottom of the V-shaped fixture. Then two aluminum nitride ceramic rod green sheets 3 are placed on the aluminum nitride ceramic rod green sheets 3. They are placed upward in sequence. Two aluminum nitride ceramic rod green sheets 3 are placed on the second layer, three aluminum nitride ceramic rod green sheets 3 are placed on the third layer, and four aluminum nitride ceramic rod green sheets 3 are placed on the fourth layer. They are placed upward in sequence as needed. The angle formed by the V-shaped fixture is an acute angle, such as 60° or 45°. The specific angle can be set according to the diameter of the aluminum nitride ceramic rod green sheets 3.

[0032] The V-shaped fixture 1 on the BN stacking support seat is used to fundamentally solve the deformation and fracture phenomenon caused by the stacking of ceramic green bodies in the prior art. The aluminum nitride ceramic rod green bodies 3 are arranged in the V-shaped fixture 1. Except for the bottom green body being affected by gravity, the aluminum nitride ceramic rod green bodies 3 arranged in the upper layer are not only affected by gravity but also balanced by the support force of the two walls. The support force of the two inclined surfaces to the aluminum nitride ceramic rod green bodies 3 is perpendicular to their respective inclined surfaces through the center of the green body. The two forces are balanced in the horizontal direction. When stacked in multiple layers, they will not be deformed due to the action of gravity. The gravity of the aluminum nitride ceramic rod green bodies 3 arranged on the same layer can be borne by the contact points of the two aluminum nitride ceramic rod green bodies 3 in the lower layer, reducing the deformation of each aluminum nitride ceramic rod green body 3 caused by gravity. The presence of BN fine powder between the green bodies will not cause green body bonding. At the same time, there is a certain gap between each aluminum nitride ceramic rod green body 3 for hot air flow exchange, which can ensure that each green body is evenly heated and contracted to ensure its verticality.

[0033] S5: The stacked aluminum nitride ceramic rod blanks 3 are spliced ​​with the front side plate 4 and the rear side plate with the BN plate. The V-shaped fixture 1 can be provided with grooves that match the front side plate 4 and the rear side plate. The front side plate 4 and the rear side plate can be clamped with the V-shaped fixture 1, and then the upper cover plate 5 is tightened and buckled with the BN fastening screws 6, so that the bottom side wall of the upper cover plate 5 is in contact with the uppermost aluminum nitride ceramic rod blank 3, and the uppermost aluminum nitride ceramic rod blank 3 is supported to avoid excessive bending of the aluminum nitride ceramic rod blank 3 during sintering, to ensure the quality of the product, and to prevent the positions of the aluminum nitride ceramic rod blanks 3 of each layer from changing during sintering;

[0034] S6: Send the BN stacking support into the atmosphere furnace, heat it to 1850℃ in N2 atmosphere and keep it for 3h for sintering, and cool it naturally after sintering to complete the firing of aluminum nitride ceramic rod;

[0035] S7: After cooling, the radial deviation of the cooked blank is tested to verify whether the preparation process has fully achieved the expected effect. The radial deviation of the product is ±0.1mm, which meets the net preparation process requirements of aluminum nitride ceramic rods with a larger length-to-diameter ratio.

[0036] The aluminum nitride ceramic rod is a cylindrical rod, the diameter of the inner cavity of the rubber mold body is equal to the diameter of the aluminum nitride ceramic rod, and the depth of the inner cavity of the rubber mold body is equal to the length of the aluminum nitride ceramic rod;

[0037] In the above step S2, the vibration frequency of the vibration platform is preferably 32 Hz, and the amplitude is 0.7 mm, which has a better effect;

[0038] In the above step S4, when the pressed aluminum nitride ceramic rod green body 3 is placed on the customized BN stacking support seat, one aluminum nitride ceramic rod green body 3 is placed at the lowest position of the V-shaped fixture 1 as the first layer, two aluminum nitride ceramic rod green bodies 3 are placed on the first layer as the second layer, and three aluminum nitride ceramic rod green bodies 3 are placed on the second layer as the third layer, and so on until the required number of layers is placed, such as the maximum number of layers that can be set to 6;

[0039] The two aluminum nitride ceramic rod green sheets 3 on the second layer are symmetrically arranged with respect to the aluminum nitride ceramic rod green sheets 3 on the first layer, and the two aluminum nitride ceramic rod green sheets 3 on the second layer are flush in the left-right direction, and are placed upward in sequence until the number of layers required to be placed is reached. Similarly, the third layer is also flush in the left-right direction after being placed, and each layer placed upward in sequence is also flush in the left-right direction;

[0040] The lower left and lower right of an aluminum nitride ceramic rod blank 3 of the first layer are supported by a V-shaped fixture 1 respectively. The lower left of the left one is supported by the V-shaped fixture 1, and the lower right is supported by the aluminum nitride ceramic rod blank 3 on the first layer. The lower left of the right one is supported by the aluminum nitride ceramic rod blank 3 of the first layer, and the lower right is supported by the V-shaped fixture 1. Going up successively, for the aluminum nitride ceramic blank on the first layer, since the lower left, lower right, upper left and upper right are all supported, it can be well supported during the sintering process to ensure its radial deviation size. Similarly, this is the case for all the upper layers except the aluminum nitride ceramic rod blank 3 on the top layer. For the aluminum nitride ceramic rod blank 3 on the top layer, the lower left and lower right are supported by the V-shaped fixture 1 or the aluminum nitride ceramic blank of the next layer, and the upper part is supported by the upper cover plate 5 to ensure the straightness requirement of the aluminum nitride ceramic rod after sintering.

[0041] The aluminum nitride ceramic rod green body 3 is prepared by the method described in the present application, which can ensure the yield and improve the production efficiency;

[0042] The through holes evenly punched on both sides of the V-shaped fixture 1 can ensure sufficient heat exchange of the hot air flow and ensure uniform shrinkage and flatness of the aluminum nitride ceramic rod green body 3;

[0043] The gravity of the aluminum nitride ceramic rod green body 3 can be balanced by the supporting forces on both sides, thereby reducing the pressure of gravity on the lower aluminum nitride ceramic rod green body 3, keeping it unchanged, and being able to sinter multiple aluminum nitride ceramic rods at one time.

[0044] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A method for preparing a large-size aluminum nitride ceramic rod, characterized in that: The method comprises: S1: A corresponding rubber mold is customized according to the specific size of the large-sized aluminum nitride ceramic rod, wherein the rubber mold includes a rubber mold body having an inner cavity and a rubber plug matched with the rubber mold body; S2: Place the customized rubber mold on a vibration platform, set the vibration frequency of the vibration platform to 30-33 Hz and the amplitude to 0.5-0.8 mm, and vibrate and fill the aluminum nitride powder. After the aluminum nitride powder is filled, insert the rubber plug into the rubber mold body and seal it to prevent moisture from entering. S3: After sealing, the sealed green body is pressed by cold isostatic pressing at a pressure of 200 MPa to form an aluminum nitride ceramic rod green body; S4: placing the pressed aluminum nitride ceramic rod green body on a customized BN stacking support seat, wherein the BN stacking support seat comprises a V-shaped fixture, an upper cover plate located above the V-shaped fixture, and a front side plate and a rear side plate located before and after the V-shaped fixture, and the green body is stacked on the V-shaped fixture. BN powder is sprinkled on the green body to prevent adhesion during stacking, wherein the V-shaped fixture, the upper cover plate, the front side plate, and the rear side plate are evenly covered with through holes, and support rods are provided on the left and right sides of the V-shaped fixture; S5: Use BN plates to splice the front and rear side plates of the stacked blanks, and then tighten and buckle the upper cover plate with BN fastening screws; S6: Send the BN stacking support into the atmosphere furnace, heat it to 1850℃ in N2 atmosphere and keep it for 3h for sintering, and cool it down naturally after sintering; S7: After cooling, the radial deviation of the cooked dough is tested to verify whether the preparation process has fully achieved the expected effect.

2. The method for preparing a large-size aluminum nitride ceramic rod according to claim 1, characterized in that: The aluminum nitride ceramic rod is a cylindrical rod, the diameter of the inner cavity of the rubber mold body is equal to the diameter of the aluminum nitride ceramic rod, and the depth of the inner cavity of the rubber mold body is equal to the length of the aluminum nitride ceramic rod.

3. The method for preparing a large-size aluminum nitride ceramic rod according to claim 1, characterized in that: In step S2, the vibration frequency of the vibration platform is 32 Hz and the amplitude is 0.7 mm.

4. The method for preparing a large-size aluminum nitride ceramic rod according to claim 1, characterized in that: In step S4, when the pressed green blanks are placed on the customized BN stacking support seat, an aluminum nitride ceramic rod green blank is placed at the lowest position of the V-shaped fixture as the first layer, two aluminum nitride ceramic rod green blanks are placed on the first layer as the second layer, three aluminum nitride ceramic rod green blanks are placed on the second layer as the third layer, and so on until the required number of layers are placed.

5. The method for preparing a large-size aluminum nitride ceramic rod according to claim 4, characterized in that: The two aluminum nitride ceramic rod green sheets on the second layer are symmetrically arranged with respect to the aluminum nitride ceramic rod green sheets on the first layer, and the two aluminum nitride ceramic rod green sheets on the second layer are flush in the left-right direction.

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