Semiconductor graphite material and preparation method thereof

Abstract

This invention belongs to the field of semiconductor graphite materials, specifically relating to a semiconductor graphite material and its preparation method. The semiconductor graphite material comprises, by mass percentage, 23-33% asphalt coke powder, 23-33% raw petroleum coke powder, 5-15% artificial graphite powder, 3-8% natural graphite powder, and the balance modified asphalt. The semiconductor graphite material exhibits high flexural strength, compressive strength, hardness, and density; low resistivity, porosity, and ash content; and a simpler preparation process, reducing production costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor graphite materials, and in particular relates to a semiconductor graphite material and a preparation method thereof. Background Art

[0002] Semiconductor materials are widely used in the modern electronics industry, including integrated circuits, solar cells, sensors, and optoelectronic devices. Graphite, a typical carbon-based material, exhibits excellent electrical, thermal, and mechanical properties, and its application in the semiconductor field has been increasing in recent years.

[0003] A prior art Chinese patent, CN 117534467 A, discloses a method for preparing a highly homogeneous specialty graphite material for epitaxial growth substrates. The main raw materials are needle-shaped petroleum coke, needle-shaped pitch coke, modified artificial graphite, and modified asphalt; the mass ratio of the needle-shaped petroleum coke, needle-shaped pitch coke, and modified artificial graphite is 5:4:1 to 8:1:1. This technical solution maintains the various properties of graphite itself while effectively enhancing specific individual properties. However, this preparation method requires impregnation and secondary carbonization, making it a complex process.

[0004] Lü Zunhua and Zhang Junhua published a study on specialty graphite for semiconductor substrates in the journal Carbon Technology. The paper described a raw material processing technique involving coating and heat-treating pitch coke, followed by spheroidization of the particles. The results showed that the treated raw materials significantly improved the strength, thermodynamic properties, electrical properties, and isotropy of the test products. However, the proposed method did not disclose the calcination process. Summary of the Invention

[0005] In response to the above problems, the present invention provides a semiconductor graphite material and a preparation method thereof. The semiconductor graphite material of the present invention has high flexural strength, compressive strength, hardness and density; has low resistivity, porosity and ash content; and the preparation process is simpler, thereby reducing production costs.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The invention provides a semiconductor graphite material. Calculated by mass percentage, the raw materials include 23-33% of pitch coke powder, 23-33% of raw petroleum coke powder, 5-15% of artificial graphite powder, 3-8% of natural graphite powder, and the balance is modified asphalt.

[0008] In some preferred embodiments, the mass ratio of the pitch coke powder, the raw petroleum coke powder, the artificial graphite powder and the natural graphite powder is 4-7:4-7:1.6-2:1.

[0009] In a preferred embodiment, the semiconductor graphite material comprises, by mass percentage, 28% asphalt coke powder, 28% raw petroleum coke powder, 9% artificial graphite powder, 5% natural graphite powder, and the remainder is modified asphalt.

[0010] In a preferred embodiment, the particle size of the asphalt coke powder: the sieve particle size -320# is 80-90%.

[0011] In the present invention, the sieve particle size -320# represents the powder content with a sieve particle size below 320 mesh.

[0012] In some preferred embodiments, the average particle size D50 of the green petroleum coke powder is 10-20 μm.

[0013] In some preferred embodiments, the particle size of the artificial graphite powder is 80-90% based on the sieve particle size -320#.

[0014] In some preferred embodiments, the particle size of the natural graphite powder is: sieve particle size -320# is 80-90%, and pH=7.

[0015] Preferably, the natural graphite powder is T395 graphite powder produced by Qingdao Nanshu Ruiying Graphite Co., Ltd.

[0016] A second aspect of the present invention provides a method for preparing the above-mentioned semiconductor graphite material, comprising the following steps:

[0017] S1, mixing asphalt coke powder, raw petroleum coke powder, artificial graphite powder and natural graphite powder for a first time, and then adding modified asphalt for a second mixing to obtain a mixture;

[0018] S2, rolling, grinding and pressing the mixed material in sequence to obtain a blank;

[0019] S3, roasting the blank according to a predetermined temperature rise curve to obtain a roasted material;

[0020] S4. Graphitizing the calcined material to obtain a semiconductor graphite material.

[0021] In some preferred embodiments, the conditions for the first mixing in step S1 are: temperature 110-130° C., and time 60-90 min.

[0022] Preferably, the conditions for the first mixing in step S1 are: temperature 120° C., and time 80 min.

[0023] In some preferred embodiments, the second mixing condition in step S2 is: first mixing with the lid closed for 80-100 minutes, and then mixing with the lid open for 3-8 minutes.

[0024] Preferably, the second mixing condition in step S1 is: first mixing with the lid closed for 90 minutes, and then mixing with the lid open for 3-8 minutes.

[0025] In some preferred embodiments, the temperature of the sheet rolling in step S2 is 175-185° C., and the sheet thickness after rolling is 2-4 mm.

[0026] In some preferred embodiments, the physical properties of the powder obtained after the grinding in step S2 are: moisture ≤ 1%, volatile matter 15-20%, sieve particle size +160# ≤ 7%, sieve particle size -320# 45-55%.

[0027] In some preferred embodiments, the pressing method in step S2 is isostatic pressing, the pressing pressure is 130-170 MPa, and the holding time is 10-20 min.

[0028] Preferably, the pressing pressure is 150 MPa and the holding time is 15 min. Preferably, the density of the blank in step S2 is 1.3-1.8 g / cm 3 .

[0029] Preferably, the density of the blank in step S2 is 1.5±0.03 g / cm 3 .

[0030] In some preferred embodiments, the predetermined heating curve in step S3 is:

[0031] Stage 1: heating from room temperature to 320-380°C at a free heating rate;

[0032] Stage 2: heating to 400-550°C at a rate of 2-4°C / h;

[0033] Stage 3: heating to 700-920°C at a rate of 1-3°C / h;

[0034] Stage 4: heating to 950-1000℃ at a heating rate of 3-5℃ / h;

[0035] Stage 5: heating to 1100-1200°C at a heating rate of 6-10°C / h;

[0036] Stage 6: Keep at 1200℃ for 60-80h.

[0037] In some preferred embodiments, the stage 2 specifically includes:

[0038] Stage 2.1: heating to 430-480°C at a rate of 3-3.5°C / h;

[0039] Stage 2.2: heating to 480-550°C at a rate of 2-3°C / h;

[0040] The stage 3 specifically includes:

[0041] Stage 3.1: heating to 730-770°C at a rate of 1-1.5°C / h;

[0042] Stage 3.2: heating to 780-820°C at a rate of 1.5-1.7°C / h;

[0043] Stage 3.3: heating to 880-920°C at a heating rate of 2-3°C / h.

[0044] Preferably, the stage 2 specifically includes:

[0045] Stage 2.1: heating to 450°C at a rate of 3.3°C / h;

[0046] Stage 2.2: heating to 500°C at a rate of 2.5°C / h;

[0047] The stage 3 specifically includes:

[0048] Stage 3.1: heating to 750°C at a rate of 1.25°C / h;

[0049] Stage 3.2: heating to 800°C at a rate of 1.6°C / h;

[0050] Stage 3.3: heating to 900°C at a heating rate of 2.5°C / h.

[0051] Most preferably, the predetermined heating curve in step S3 is:

[0052] Stage 1: heating from room temperature to 350 °C at a free heating rate of 5 h;

[0053] Stage 2.1: heating to 450°C at a rate of 3.3°C / h;

[0054] Stage 2.2: heating to 500°C at a rate of 2.5°C / h;

[0055] Stage 3.1: heating to 750°C at a rate of 1.25°C / h;

[0056] Stage 3.2: heating to 800°C at a rate of 1.6°C / h;

[0057] Stage 3.3: heating to 900°C at a rate of 2.5°C / h;

[0058] Stage 4: heating to 980°C at a rate of 4°C / h;

[0059] Stage 5: heating to 1180°C at a rate of 8°C / h;

[0060] Stage 6: Keep at 1200℃ for 70h.

[0061] In some preferred embodiments, the conditions for the graphitization treatment in step S4 are:

[0062] (1) Place the roasted material in a graphitization furnace, and when the furnace core temperature is 2000-2200°C, supply chlorine gas, and when it is 2200-2400°C, supply Freon; or when the furnace core temperature is 2000-2200°C, supply chlorine gas, and after 6 hours of supplying chlorine gas, supply Freon and chlorine gas simultaneously;

[0063] (2) Graphitization treatment at 2800-3000℃ for 40-50h.

[0064] Preferably, during the simultaneous delivery of freon and chlorine, the amount of chlorine is slightly greater than the amount of freon.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] By adopting specific raw materials and optimized roasting conditions, the present invention only requires one roasting treatment and graphitization treatment, and no impregnation is required. The preparation method is simple and efficient, and the production cost is reduced. The obtained semiconductor graphite material has high flexural strength, compressive strength, hardness and density; and has low resistivity, porosity and ash content. DETAILED DESCRIPTION

[0067] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0068] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0069] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0070] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0071] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0072] In the following examples, unless otherwise specified, all raw materials used were purchased from commercial sources or prepared by conventional methods in the art.

[0073] The sources of raw materials involved in the examples and comparative examples are shown in Table 1:

[0074] Table 1

[0075]

[0076] Examples 1-3 and Comparative Examples 1-4 provide a semiconductor graphite material, the composition of which is shown in Table 2 in terms of mass percentage:

[0077] Table 2

[0078] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Pitch coke powder 23％ 28％ 33％ 28％ 0％ 39％ 56％ Raw petroleum coke powder 23％ 28％ 33％ 28％ 56％ 15％ 0％ Artificial graphite powder 15％ 9％ 5％ 14％ 9％ 9％ 9％ T395 graphite powder 8％ 5％ 3％ 0％ 5％ 5％ 5％ Reformed asphalt 31％ 30％ 26％ 30％ 30％ 32％ 30％

[0079] The preparation methods of Examples 1-3 and Comparative Examples 1-4 comprise the following steps:

[0080] S1. Asphalt coke powder, raw petroleum coke powder, artificial graphite powder and natural graphite powder were mixed for the first time at a temperature of 120° C. for 80 minutes, and then modified asphalt was added and mixed for 90 minutes with the lid closed, and then for 5 minutes with the lid open to obtain a mixture;

[0081] S2. rolling the mixed material into sheets: the sheeting temperature is 180°C, and the sheet thickness after rolling is 3 mm;

[0082] Grinding: 4R grinding mill is used for grinding; the physical properties of the powder obtained after grinding are as follows: moisture: ≤1%; volatile matter: 12-18%; +160#: ≤7%; -320#: 45-55%;

[0083] Isostatic pressing: pressure is 150 MPa, holding time is 15 min, and the blank is obtained; the density of the blank is 1.5 ± 0.03 g / cm 3 ;

[0084] S3, calcining the blank according to a predetermined temperature rise curve to obtain a calcined material;

[0085] The predetermined heating curve is:

[0086] Stage 1: heating from room temperature to 350 °C at a free heating rate of 5 h;

[0087] Stage 2.1: heating to 450°C at a rate of 3.3°C / h;

[0088] Stage 2.2: heating to 500°C at a rate of 2.5°C / h;

[0089] Stage 3.1: heating to 750°C at a rate of 1.25°C / h;

[0090] Stage 3.2: heating to 800°C at a rate of 1.6°C / h;

[0091] Stage 3.3: heating to 900°C at a rate of 2.5°C / h;

[0092] Stage 4: heating to 980°C at a rate of 4°C / h;

[0093] Stage 5: heating to 1180°C at a rate of 8°C / h;

[0094] Stage 6: Keep at 1200℃ for 70h;

[0095] S4. Place the roasted material in a graphitization furnace. When the furnace core temperature is 2000℃, add chlorine gas; when it is 2200℃, add Freon; and graphitize at 3000℃ for 48 hours to obtain the product.

[0096] Comparative Example 5

[0097] The difference from Example 2 is that the predetermined heating curve in step S3 is:

[0098] Stage 1: heating from room temperature to 350°C at a free heating rate;

[0099] Stage 2: heating to 500°C at a rate of 3.3°C / h;

[0100] Stage 3.1: heating to 800°C at a rate of 1.25°C / h;

[0101] Stage 3.2: heating to 900°C at a rate of 2.5°C / h;

[0102] Stage 4: heating to 1180°C at a rate of 8°C / h;

[0103] Stage 5: Keep at 1200℃ for 70h.

[0104] Comparative Example 6

[0105] The difference from Example 2 is that the predetermined heating curve in step S3 is:

[0106] Stage 1: heating from room temperature to 350°C at a free heating rate;

[0107] Stage 2.1: heating to 450°C at a rate of 2.5°C / h;

[0108] Stage 2.2: heating to 500°C at a heating rate of 3.5°C / h.

[0109] Stage 3: heating to 800°C at a rate of 1.25°C / h;

[0110] Stage 3.1: heating to 750°C at a rate of 2°C / h;

[0111] Stage 3.2: heating to 800°C at a rate of 1°C / h;

[0112] Stage 3.3: heating to 900°C at a rate of 3°C / h;

[0113] Stage 4: heating to 980°C at a rate of 6°C / h;

[0114] Stage 5: heating to 1180°C at a rate of 4°C / h;

[0115] Stage 6: Keep at 1200℃ for 70h.

[0116] Comparative Example 7

[0117] The difference from Example 2 is that the predetermined heating curve in step S3 is:

[0118] Stage 1: heating from room temperature to 200°C at a free heating rate;

[0119] Stage 2: heating to 600°C at a rate of 10°C / h;

[0120] Stage 3: heating to 900°C at a heating rate of 3°C / h;

[0121] Stage 4: heating to 1000°C at a heating rate of 7°C / h;

[0122] Stage 5: heating to 1150°C at a rate of 15°C / h;

[0123] Stage 6: Keep at 1150℃ for 50h.

[0124] The semiconductor graphite materials of Examples 1-3 and Comparative Examples 1-7 were subjected to performance tests, wherein the flexural strength test standard was JB / T 8133.7 Test Method for Physical and Chemical Properties of Electric Carbon Products Part 7; the compressive strength test standard was JB / T 8133.8 Test Method for Physical and Chemical Properties of Electric Carbon Products Part 8; the resistivity test standard was JB / T 8133.2 Test Method for Physical and Chemical Properties of Electric Carbon Products Part 2; the hardness test standard was JB / T 8133.4 Test Method for Physical and Chemical Properties of Electric Carbon Products Part 4; the bulk density test standard was JB / T 8133.14 Test Method for Physical and Chemical Properties of Electric Carbon Products Part 14; and the porosity test standard was JB / T 8133.15 Test Method for Physical and Chemical Properties of Electric Carbon Products Part 15. The results are shown in Table 3.

[0125] Table 3

[0126]

[0127]

[0128] The semiconductor graphite material of the embodiment of the present invention has been tried out on graphite bases and clips used in semiconductor silicon wafer production by a company in my country.

[0129] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A semiconductor graphite material, characterized in that: Calculated by mass percentage, the raw materials include 23-33% asphalt coke powder, 23-33% raw petroleum coke powder, 5-15% artificial graphite powder, 3-8% natural graphite powder, and the balance is modified asphalt; The method for preparing the semiconductor graphite material comprises the following steps: S1, mixing asphalt coke powder, raw petroleum coke powder, artificial graphite powder and natural graphite powder for a first time, and then adding modified asphalt for a second mixing to obtain a mixture; S2, rolling, grinding and pressing the mixed material in sequence to obtain a blank; S3, roasting the blank according to a predetermined temperature rise curve to obtain a roasted material; S4, graphitizing the calcined material to obtain a semiconductor graphite material; The predetermined heating curve in step S3 is: Stage 1: heating from room temperature to 350 °C at a free heating rate of 5 h; Stage 2.1: heating to 450°C at a rate of 3.3°C / h; Stage 2.2: heating to 500°C at a rate of 2.5°C / h; Stage 3.1: heating to 750°C at a rate of 1.25°C / h; Stage 3.2: heating to 800°C at a rate of 1.6°C / h; Stage 3.3: heating to 900°C at a rate of 2.5°C / h; Stage 4: heating to 980°C at a rate of 4°C / h; Stage 5: heating to 1180°C at a rate of 8°C / h; Stage 6: Keep at 1200℃ for 70h.

2. The semiconductor graphite material according to claim 1, characterized in that The mass ratio of the pitch coke powder, the raw petroleum coke powder, the artificial graphite powder and the natural graphite powder is 4-7:4-7:1.6-2:

1.

3. The semiconductor graphite material according to claim 1, characterized in that The semiconductor graphite material comprises, by mass percentage, 28% asphalt coke powder, 28% raw petroleum coke powder, 9% artificial graphite powder, 5% natural graphite powder, and the balance being modified asphalt.

4. The semiconductor graphite material according to claim 1, characterized in that The physical properties of the powder obtained after the grinding in step S2 are as follows: moisture ≤ 1%, volatile matter 15-20%, sieve particle size +160# ≤ 7%, sieve particle size -320# 45-55%.

5. The semiconductor graphite material according to claim 1, characterized in that The density of the blank in step S2 is 1.3-1.8 g / cm 3 .

6. The semiconductor graphite material according to claim 1, characterized in that The conditions for the graphitization treatment in step S4 are: (1) Place the roasted material in a graphitization furnace. When the furnace core temperature is 2000-2200℃, supply chlorine gas, and when it is 2200-2400℃, supply Freon; or when the furnace core temperature is 2000-2200℃, supply chlorine gas, and after 6 hours of supplying chlorine gas, supply Freon and chlorine gas simultaneously; (2) Graphitization treatment at 2800-3000℃ for 40-50h.

Images