Preparation method of a high-performance large-sized carbon target material

Abstract

A method for preparing a high-performance large-size carbon target. The carbon target uses high-purity methane gas as the carbon source gas, and nitrogen and hydrogen as the dilution gas and carrier gas, and is prepared by chemical vapor deposition. First, the carbon target grows horizontally at the bottom for 1-5 mm. Then, the gas flow pattern is changed to make the carbon target grow vertically for 5-10 mm. Next, the carbon target grows horizontally at the top for 1-5 mm to obtain a large-size carbon target blank with two growth directions. Finally, the carbon grown horizontally with a thickness of 1-5 mm at the bottom and top is removed by machining to obtain a high-performance large-size carbon target with a diameter ≥ 400 mm, a thickness of 5-10 mm, and a density ≥ 2.1 g / cm 3 , and a purity ≥ 5N; compared with the prior art, this method has the following advantages: (1) a large-size carbon target can be obtained; (2) the process is simple and the production efficiency is improved; (3) the density of the target is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetron sputtering target manufacturing, and particularly relates to a method for preparing a high-performance large-size carbon target. Background Art

[0002] Due to the characteristics of high hardness, low friction coefficient and high chemical stability, carbon thin films are often used to prepare protective layers and lubricating layers for advanced storage devices. The carbon thin films for advanced storage devices are mainly prepared by magnetron sputtering of carbon targets. Currently, carbon targets are mainly prepared by isostatic pressing graphite, with a relatively low density (1.7 - 1.9 g / cm 3 ), and arcing and particle phenomena are likely to occur during the magnetron sputtering coating process, affecting the yield of the thin film. The high-purity carbon targets prepared by chemical deposition method have a higher density (1.9 - 2.2 g / cm 3 ), which can effectively avoid arcing and particle phenomena. However, due to the single orientation of the high-purity carbon targets prepared by chemical deposition method, the physical properties such as thermal conductivity and thermal expansion coefficient in the horizontal and vertical directions are quite different, and the stress in different directions after deposition is relatively large, making it easy to crack during the cooling stage and difficult to prepare large-size carbon targets. Summary of the Invention

[0003] Aiming at the problems mentioned in the prior art, the present invention provides a method for preparing a high-performance large-size carbon target. The carbon target is prepared by chemical vapor deposition method, including: Step (1) growing the carbon target horizontally at the bottom for 1 - 5 mm; Step (2) changing the gas flow pattern to grow the carbon target vertically for 5 - 10 mm; Step (3) then growing the carbon target horizontally at the top for 1 - 5 mm to obtain a large-size carbon target blank with two growth directions; Step (4) using machining to remove the carbon grown horizontally at the bottom and top with a thickness of 1 - 5 mm to obtain a high-performance large-size carbon target with a single orientation.

[0004] In the present invention, in Step (4), a high-performance large-size carbon target with a diameter ≥ 400 mm, a thickness of 5 - 10 mm, a density ≥ 2.1 g / cm 3 , and a purity ≥ 5N can be obtained.

[0005] The manufacturing process of the present invention utilizes the carbon targets grown horizontally at the bottom and top to offset or reduce the stress generated during the cooling process of the carbon target grown vertically in the middle, thereby obtaining a large-size high-performance carbon target.

[0006] In the present invention, the thickness of the carbon target material grown in the horizontal direction at the bottom and the top depends on the thickness of the carbon target material to be prepared in the middle in the vertical direction. For example, when the thickness of the carbon target material in the vertical direction is 10 mm, the thickness of the carbon target material grown in the horizontal direction at the bottom and the top is about 4 - 5 mm; while when the thickness of the carbon target material in the vertical direction is 5 mm, the thickness of the carbon target material grown in the horizontal direction at the bottom and the top is about 1 - 2 mm. In this way, during the cooling process, the stress changes generated by the carbon target material grown in the middle in the vertical direction are offset or reduced by using the carbon target material grown in the horizontal direction at the bottom and the top.

[0007] Specifically, the present invention provides a method for preparing a high-performance large-size carbon target material, which includes the following steps:

[0008] (1) Place a graphite substrate with a diameter ≥ 400 mm in a chemical deposition furnace and heat it to 1800 - 2000 °C;

[0009] (2) Input high-purity methane, nitrogen, and hydrogen. The methane flow rate ranges from 0.5 to 2.0 L / min, the nitrogen flow rate ranges from 0.1 to 15 L / min, and the hydrogen flow rate ranges from 0.1 to 1 L / min to deposit the carbon target material horizontally at the bottom of the graphite substrate for 1 - 5 mm;

[0010] (3) Change the gas flow pattern and continue to grow the carbon target material vertically on the surface of the carbon target material obtained in step (2) for 5 - 10 mm;

[0011] (4) Change the gas flow pattern again and continue to grow the carbon target material horizontally on the surface of the carbon target material obtained in step (3) for 1 - 5 mm;

[0012] (5) Slowly cool down to obtain a large-size carbon target material with two growth directions and no cracks and a diameter ≥ 400 mm;

[0013] (6) Remove the carbon grown horizontally with a thickness of 1 - 5 mm at the bottom and the top, and finally obtain a high-performance large-size carbon target material with a single orientation, a diameter ≥ 400 mm, a thickness of 5 - 10 mm, and a density ≥ 2.1 g / cm 3 , and a purity ≥ 5N.

[0014] Compared with the prior art, the present technical solution has the following advantages:

[0015] (1) A large-size carbon target material can be obtained: By using the principle that the anisotropy of the carbon target material grown in the horizontal direction and the vertical direction offsets each other, the stress caused by the physical property differences of the carbon target material during the cooling process can be effectively avoided, and a large-size carbon target material can be obtained;

[0016] (2) The process is simple and the production efficiency is improved: The present technical solution can directly obtain a large-size carbon target material with only 6 processes. Compared with the isostatic graphite preparation process with 9 processes, the process is simple and the production efficiency is improved.

[0017] (3) High density of the target: The density of the carbon target prepared by chemical deposition method is ≥ 2.1 g / cm 3 , which is greater than that of the carbon target prepared by isostatic pressing graphite (1.7 - 1.9 g / cm 3 ).

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it does not mean to limit the protection scope of the present invention. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of preparing a carbon target for the present invention patent.

[0020] As Figure 1 shown, the preparation method of the present invention includes:

[0021] (1) Place the graphite substrate in a chemical deposition furnace;

[0022] (2) Heat it to 1800 - 2000 °C;

[0023] (3) Input high-purity methane, nitrogen and hydrogen;

[0024] (4) Deposit the carbon target at the bottom of the graphite substrate horizontally for 1 - 5 mm;

[0025] (5) Change the gas flow pattern and continue to grow it vertically for 5 - 10 mm;

[0026] (6) Change the gas flow pattern again and continue to grow it horizontally on the surface of the carbon target for 1 - 5 mm;

[0027] (7) Slowly cool down;

[0028] (8) Remove the carbon grown horizontally at the bottom and top;

[0029] (9) Obtain a high-performance large-size carbon target with a single orientation. Specific Embodiments

[0030] The invention mechanism of the present invention is as follows: First, make the carbon target grow horizontally at the bottom for 1 - 5 mm, then change the gas flow pattern to make the carbon target grow vertically for 5 - 10 mm, and finally make the carbon target grow horizontally at the top for 1 - 5 mm to obtain a large-size carbon target blank with two growth directions. Use machining to remove the carbon grown horizontally with a thickness of 1 - 5 mm at the bottom and top to obtain a carbon target with a diameter ≥ 400 mm, a thickness of 5 - 10 mm, and a density ≥ 2.1 g / cm 3, a high-performance large-size carbon target with a purity of ≥5N. The manufacturing process of the present invention utilizes the horizontal growth of carbon targets at the bottom and top to offset or reduce the stress generated during the cooling process of the carbon target grown vertically in the middle, thereby obtaining a large-size high-performance carbon target.

[0031] To better explain the present invention for easy understanding, the present invention will be described in detail below through specific examples and comparative examples.

[0032] In addition, in all examples and comparative examples, the graphite matrix used is a graphite matrix prepared according to the prior art, and the high-purity methane, nitrogen, and hydrogen used are industrially pure (purity greater than 99.99%). The equipment used is the equipment known in the prior art.

[0033] Examples 1-9

[0034] 1. Place a graphite matrix with a diameter of ≥400 mm in a chemical vapor deposition (CVD) furnace and heat it to 1800-2000 °C.

[0035] 2. Input high-purity methane, nitrogen, and hydrogen. The methane flow rate ranges from 0.5 to 2.0 L / min, the nitrogen flow rate ranges from 0.1 to 15 L / min, and the hydrogen flow rate ranges from 0.1 to 1 L / min to deposit 1-5 mm of carbon target horizontally at the bottom of the graphite matrix.

[0036] 3. Change the gas flow pattern and continue to grow 5-10 mm vertically on the surface of the carbon target.

[0037] 4. Change the gas flow pattern again and continue to grow 1-5 mm horizontally on the surface of the carbon target.

[0038] 5. Slowly cool down to obtain a large-size carbon target with a diameter of ≥400 mm and no cracks in two growth directions.

[0039] 6. Remove the carbon grown horizontally with a thickness of 1-5 mm at the bottom and top, and finally obtain a high-performance large-size carbon target with a single orientation, a diameter of ≥400 mm, a thickness of 5-10 mm, and a density of ≥2.1 g / cm 3 , with a purity of ≥5N.

[0040] Comparative Example 1

[0041] 1. Place a graphite matrix with a diameter of 400 mm in a chemical vapor deposition furnace and heat it to 1800 °C.

[0042] 2. Input high-purity hydrocarbon gas to grow 5 mm of carbon target vertically on the graphite matrix.

[0043] 3. Slowly cool down to obtain a carbon target with a diameter of 400 mm, a thickness of 5 mm, and a density of 2.10 g / cm 3, cracked carbon target with a purity of ≥5N.

[0044] Comparative Example 2

[0045] 1. Place a graphite substrate with a diameter of 450 mm in a chemical deposition furnace and heat it to 2000 °C.

[0046] 2. Input high-purity hydrocarbon gas to grow the carbon target vertically on the graphite substrate by 10 mm.

[0047] 3. Slowly cool down to obtain a carbon target with a diameter of 450 mm, a thickness of 10 mm, and a density of 2.20 g / cm 3 , cracked carbon target with a purity of ≥5N.

[0048] Comparative Example 3

[0049] 1. Airflow pulverization: Calcined petroleum coke or pitch coke is coarsely crushed and then pulverized by an airflow pulverizer to make coke powder with an average particle size of 20 μm;

[0050] 2. Primary kneading and rolling: The ratio of coke powder to modified asphalt is 60 - 73:40 - 27. Knead under normal pressure for 2.5 h at a temperature of 180 °C. After the paste kneading is completed, roll the paste while it is hot. The rolling temperature is 170 °C, and the number of rolling times is 10 times;

[0051] 3. Extrusion molding: After the paste cools, crush it to less than 2 mm and extrude it into a slender rod with a diameter of Φ10 mm using a screw extruder;

[0052] 4. Rapid carbonization: Place the slender rod in an autoclave and carry out pressure carbonization at 650 °C and a pressure of 2.5 MPa for 10 h;

[0053] 5. Crushing and screening: After carbonization, crush and pass through a 200-mesh sieve;

[0054] 6. Secondary kneading and rolling: Knead and roll the sieved coke powder with modified asphalt in a certain proportion;

[0055] 7. Crushing and screening: Crush and pass through a 150-mesh sieve to obtain pressed powder;

[0056] 8. Pre-forming: Load the pressed powder into a steel mold and pre-form it under a pressure of 20 MPa;

[0057] 9. Isostatic pressing, baking, impregnation, graphitization: The pre-formed blank is made into isostatic graphite after subsequent processes such as isostatic pressing, impregnation, baking, and graphitization. Among them, isostatic pressing is cold pressing at a pressure of 180 MPa, and demolding is carried out after holding the pressure for 10 minutes. The blank after isostatic pressing is heated to 1000 °C at a heating rate of 10 °C / h under N2 protection, which is the first baking. After cooling and taking out of the furnace, at 260 °C and a pressure of 3.0 MPa, medium-temperature pitch is used for impregnation for 4 h, which is the first impregnation. Then, the second baking is carried out at a temperature of 900 °C. After the blank after the second baking is naturally cooled, it is impregnated again with high-temperature pitch for 4 h at 320 °C and a pressure of 3.5 MPa, which is the second impregnation. Then, the third baking is carried out at a temperature of 900 °C. The blank after the third baking is placed in a graphitization furnace with intermediate-frequency induction heating, and is heated to 2500 °C at a heating rate of 150 °C / h under Ar protection and held at a constant temperature for 1 h, obtaining a carbon target with a diameter of 450 mm, a thickness of 10 mm, and a density of 1.77 g / cm 3 , and a carbon target with a purity of ≥5N.

[0058] The main manufacturing processes and performance results of the carbon targets in Examples 1-9 and Comparative Examples 1-3 are shown in Table 1.

[0059] Table 1 Main manufacturing processes and properties of carbon targets in implementation cases and comparative cases

[0060]

[0061] From the results of the above Examples 1-9 and Comparative Examples 1-3, it can be seen that by using the method of the present invention, a high-performance large-size carbon target with a single orientation, a diameter of ≥400 mm, a thickness of 5-10 mm, a density of ≥2.1 g / cm 3 , and a purity of ≥5N can be obtained. However, by using the existing technology, for example: in Comparative Example 1, a cracked carbon target with a diameter of 400 mm, a thickness of 5 mm, a density of 2.10 g / cm 3 , and a purity of ≥5N is obtained; in Comparative Example 2, a cracked carbon target with a diameter of 450 mm, a thickness of 10 mm, a density of 2.20 g / cm 3 , and a purity of ≥5N is obtained; in Comparative Example 3, a carbon target with a diameter of 450 mm, a thickness of 10 mm, and a purity of ≥5N is prepared, and its density is only 1.77 g / cm 3 .

[0062] Obviously, compared with the existing technology, the technical solution of the present invention has the following advantages:

[0063] (1) Large-size carbon targets can be obtained; (2) The process is simple and the production efficiency is improved: (3) The density of the target is high.

[0064] Other embodiments of the present disclosure will be readily apparent to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include known common general knowledge or conventional technical means in the technical field not disclosed in the present disclosure. The specification and examples are only to be considered as exemplary, and the true scope and spirit of the present disclosure are pointed out by the claims of the present invention.

Claims

1. A preparation method of a carbon target, comprising the following steps: (1) Place a graphite substrate with a diameter ≥ 400 mm in a chemical deposition furnace and heat it to 1800 - 2000 °C; (2) Input high-purity methane, nitrogen, and hydrogen to deposit the carbon target 1 - 5 mm horizontally at the bottom of the graphite substrate; (3) Change the gas flow pattern and continue to grow it 5 - 10 mm vertically on the surface of the carbon target obtained in step (2); (4) Change the gas flow pattern again and continue to grow it 1 - 5 mm horizontally on the surface of the carbon target obtained in step (3); (5) Slowly cool down to obtain a carbon target with a diameter ≥ 400 mm and no cracks in two growth directions; (6) Remove the carbon grown horizontally with a thickness of 1 - 5 mm at the bottom and the top, and finally obtain a carbon target with a single orientation; In step (2), the methane flow rate ranges from 0.5 to 2.0 L / min, the nitrogen flow rate ranges from 0.1 to 15 L / min, and the hydrogen flow rate ranges from 0.1 to 1 L / min.

2. According to the preparation method of the carbon target described in claim 1, the thickness of the carbon target grown horizontally at the bottom or the top in step (2) or step (4) depends on the thickness of the carbon target to be prepared vertically in the middle. When the thickness of the carbon target in the vertical direction is 10 mm, the thickness of the carbon target grown horizontally at the bottom and the top is 4 - 5 mm; while when the thickness of the carbon target in the vertical direction is 5 mm, the thickness of the carbon target grown horizontally at the bottom and the top is 1 - 2 mm.

3. According to the preparation method described in claim 1, in step (6), a carbon target with a diameter ≥ 400 mm, a thickness of 5 - 10 mm, a density ≥ 2.1 g / cm 3 , and a purity ≥ 5N is obtained.

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