A method for preparing a diamond semiconductor device and a diamond semiconductor device

Abstract

The embodiment of the present invention discloses a method for preparing a diamond semiconductor device and a diamond semiconductor device. The method for preparing the diamond semiconductor device comprises: providing a diamond substrate; spin coating a photoresist on one side of the diamond substrate; patterning the photoresist to obtain a photoresist plane structure; annealing the photoresist plane structure to obtain a graphite electrode; wherein the shape of the graphite electrode is the same as the shape of the photoresist plane structure, and the annealing temperature is greater than or equal to the growth temperature of the diamond. The technical solution provided by this embodiment has a simple process, is easy to implement, and has a lower cost. It will not cause damage to the diamond material itself, and the carbon atoms on the surface of the diamond form bonds with the carbon atoms in the graphite electrode, so that the defect density of the interface between the diamond and the graphite electrode is small, the interface resistance is reduced, the contact performance is improved, and the performance of the diamond semiconductor device is improved, which provides a new method for the realization of the diamond semiconductor device.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of semiconductor technology, and in particular to a method for preparing a diamond semiconductor device and a diamond semiconductor device. Background Art

[0002] Diamond has various excellent properties such as the highest thermal conductivity, the highest breakdown electric field, extremely high carrier mobility and strong radiation resistance. It is hailed as the "ultimate semiconductor" by the industry and has a huge application market in 5G communications, aerospace, high-speed rail transit, new energy vehicles and other fields.

[0003] Existing diamond semiconductor devices generally use precious metals such as Pt and Au to prepare ohmic contact electrodes, which have high preparation costs and high interface defect density of the prepared electrodes, which is not conducive to meeting the requirements of diamond semiconductor devices for low interface resistance.

[0004] Currently, graphite electrodes are generally prepared by laser ablation of diamond materials to form graphite electrodes, but the process conditions and cost requirements are relatively high, which is not conducive to industrial mass production. Summary of the invention

[0005] The embodiments of the present invention provide a method for preparing a diamond semiconductor device and a diamond semiconductor device, so as to solve the problems of high cost and high interface resistance of the existing electrode manufacturing method.

[0006] In order to achieve the above technical problems, the present invention adopts the following technical solutions:

[0007] An embodiment of the present invention provides a method for preparing a diamond semiconductor device, comprising:

[0008] providing a diamond substrate;

[0009] Spin coating a photoresist on one side of the diamond substrate;

[0010] Patterning the photoresist to obtain a photoresist planar structure;

[0011] The photoresist planar structure is pyrolyzed to obtain a graphite electrode; wherein the shape of the graphite electrode is the same as the shape of the photoresist planar structure, and the annealing temperature is greater than or equal to the growth temperature of the diamond.

[0012] Optionally, the step of spin coating the photoresist on one side of the diamond substrate comprises:

[0013] A positive photoresist or a negative photoresist is spin-coated on one side of the diamond substrate.

[0014] Optionally, patterning the photoresist to obtain a photoresist planar structure includes:

[0015] After the photoresist is subjected to pre-baking, exposure, post-baking, development and hardening process, a photoresist plane structure arranged on one side of the diamond substrate is obtained.

[0016] Optionally, the step of pyrolyzing the photoresist planar structure to obtain a graphite electrode comprises:

[0017] Sending the diamond substrate having the photoresist planar structure into an annealing furnace;

[0018] The photoresist plane structure is annealed in an atmosphere with a fixed flow rate of inert gas to obtain the graphite electrode.

[0019] Optionally, annealing the photoresist planar structure in an atmosphere into which a fixed flow of inert gas is introduced to obtain the graphite electrode comprises:

[0020] In the first stage, starting from the starting temperature, the temperature of the photoresist planar structure is raised to a first intermediate temperature at a preset temperature changing rate for a first preset time in an atmosphere of an inert gas with a fixed flow rate;

[0021] In the second stage, the first intermediate temperature is maintained for a second preset time;

[0022] In the third stage, starting from the first intermediate temperature and continuing at the preset temperature changing rate for the first preset time, the photoresist planar structure is heated to a second intermediate temperature in an atmosphere with a fixed flow rate of inert gas;

[0023] In the fourth stage, the second intermediate temperature is maintained for a second preset time;

[0024] In the fifth stage, starting from the second intermediate temperature and continuing at the preset temperature changing rate for the first preset time, the photoresist planar structure is heated to the target temperature in an atmosphere with a fixed flow rate of inert gas;

[0025] In the sixth stage, the target temperature is maintained for a second preset time to obtain the graphite electrode; wherein the first preset time is greater than the second preset time.

[0026] Optionally, the first stage includes a first sub-stage and a second sub-stage located after the first sub-stage;

[0027] The first preset temperature change rate of the first sub-stage includes a first sub-rate, and the first preset temperature change rate of the second sub-stage includes a second sub-rate;

[0028] The first sub-rate is less than the second sub-rate;

[0029] The second sub-rate is less than or equal to the preset temperature change rate of the third stage;

[0030] The second sub-rate is less than or equal to the preset temperature change rate of the fifth stage.

[0031] Optionally, the second preset time is half of the first preset time;

[0032] The temperature difference between the first intermediate temperature and the second intermediate temperature is equal to the temperature difference between the target temperature and the second intermediate temperature;

[0033] The target temperature ranges from 800°C to 1100°C.

[0034] Optionally, providing a diamond substrate comprises:

[0035] A diamond film is epitaxially grown on one side of a polished substrate using microwave plasma chemical vapor deposition technology;

[0036] The reaction gases are methane and hydrogen, and the gas flow ratio of the methane to the hydrogen is 1:50 to 1:5; the microwave power is 3000W to 6000W, the growth pressure is 30torr to 200torr, and the temperature is 800°C to 1100°C.

[0037] Optionally, the diamond film thickness ranges from 0.1 μm to 50 μm;

[0038] The thickness of the graphite electrode ranges from 30nm to 500nm;

[0039] The material of the photoresist includes phenolic resin.

[0040] According to another aspect of the present invention, this embodiment provides a diamond semiconductor device, comprising:

[0041] Diamond substrate;

[0042] A graphite electrode is arranged on one side of the diamond substrate; wherein the graphite electrode is obtained by patterning the photoresist on one side of the diamond substrate to obtain a photoresist plane structure, and annealing the photoresist plane structure; the shape of the graphite electrode is the same as the shape of the photoresist plane structure, and the annealing temperature is greater than or equal to the growth temperature of the diamond.

[0043] The method for preparing a diamond semiconductor device provided in an embodiment of the present invention adopts a method of spin coating a photoresist on the surface of a diamond substrate, patterning the photoresist, and then pyrolyzing it to obtain a graphite electrode. Compared with the laser ablation diamond process, the technical solution provided in this embodiment is simple in process, easy to implement, and has lower cost. It is compatible with the current photolithography equipment in the semiconductor industry for mass production, and will not cause damage to the diamond material itself. In addition, the carbon atoms on the surface of the diamond and the carbon atoms in the graphite electrode form bonds, so that the defect density of the interface between the diamond and the graphite electrode is small, the interface resistance is reduced, the contact performance is improved, and the performance of the diamond semiconductor device is improved, which provides a new method for the realization of the diamond semiconductor device. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0045] Figure 1 is a flow chart of a method for preparing a diamond semiconductor device provided by an embodiment of the present invention;

[0046] Figure 2 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention;

[0047] Figure 3 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention;

[0048] Figure 4 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention;

[0049] Figure 5 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention;

[0050] Figure 6 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention;

[0051] Figure 7 It is a schematic diagram of a process for preparing a diamond semiconductor device provided by an embodiment of the present invention;

[0052] Figure 8 This is a Raman spectrum of a graphite electrode provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0054] Figure 1 The present invention provides a flowchart of a method for preparing a diamond semiconductor device.

[0055] See also Figure 1 , a method for preparing a diamond semiconductor device provided by an embodiment of the present invention comprises:

[0056] S101. Provide a diamond substrate.

[0057] S102, spin coating photoresist on one side of the diamond substrate.

[0058] S103, patterning the photoresist to obtain a photoresist planar structure.

[0059] S104, annealing the photoresist planar structure to obtain a graphite electrode; wherein the shape of the graphite electrode is the same as the shape of the photoresist planar structure, and the annealing temperature is greater than or equal to the growth temperature of the diamond.

[0060] Specifically, a photoresist is spin-coated on one side of a diamond substrate and patterned, for example, by photolithography, to form a finger-shaped photoresist plane structure. The photoresist plane structure is still in the form of a thin film. The photoresist plane structure is pyrolyzed to obtain a graphite electrode, which is still in the form of a thin film, but non-C elements such as H and O in the photoresist plane structure continuously escape in the form of water or other molecules as the temperature rises, and the photoresist plane structure is transformed into graphite or a graphite-containing material with high conductivity, and is used as a graphite electrode.

[0061] Diamonds are composed entirely of carbon SP3, and graphite electrodes are also composed of carbon atoms. The temperature in the process of preparing graphite electrodes reaches the growth temperature of diamond, so that the carbon atoms on the surface of the diamond and the carbon atoms in the graphite electrode form bonds, making the defect density at the interface between the diamond and the graphite electrode smaller, reducing the interface resistance, and improving the contact performance, thereby improving the performance of diamond semiconductor devices and reducing power consumption.

[0062] The method for preparing the diamond semiconductor device provided in this embodiment adopts a method of spin coating a photoresist on the surface of a diamond substrate, patterning the photoresist and then pyrolyzing it to obtain a graphite electrode, and the graphite electrode may include a graphite electrode or a carbon micrographite electrode. Compared with the laser ablation process, the technical solution provided in this embodiment is simple in process, easy to implement, and has lower cost. It is compatible with the current photolithography equipment in the semiconductor industry for mass production, and will not cause damage to the diamond material itself. It provides a new method for the realization of diamond semiconductor devices, such as all-carbon solar-blind ultraviolet detection devices, and solves the problem that the existing electrode manufacturing method has high cost and high interface resistance.

[0063] Optional, Figure 2 FIG. 1 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention. Figure 2 , a method for preparing a diamond semiconductor device provided by an embodiment of the present invention comprises:

[0064] S101. Provide a diamond substrate.

[0065] S201, spin coating a positive photoresist or a negative photoresist on one side of the diamond substrate.

[0066] Specifically, a coating machine may be used to spin-coat AZ positive photoresist or negative photoresist onto the surface of the diamond film as required, and no limitation is made herein.

[0067] S103, patterning the photoresist to obtain a photoresist planar structure.

[0068] S104, annealing the photoresist planar structure to obtain a graphite electrode; wherein the shape of the graphite electrode is the same as the shape of the photoresist planar structure, and the annealing temperature is greater than or equal to the growth temperature of the diamond.

[0069] Optional, Figure 3 FIG. 1 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention. Figure 3 , a method for preparing a diamond semiconductor device provided by an embodiment of the present invention comprises:

[0070] S101. Provide a diamond substrate.

[0071] S102, spin coating photoresist on one side of the diamond substrate.

[0072] S301, subjecting the photoresist to pre-baking, exposure, post-baking, development and hardening processes to obtain a photoresist planar structure disposed on one side of the diamond substrate.

[0073] Specifically, the shape of the photoresist planar structure is the same as the shape of the graphite electrode to be finally produced, which is convenient for improving the preparation accuracy of the electrode and reducing the process difficulty.

[0074] S104, annealing the photoresist planar structure to obtain a graphite electrode; wherein the shape of the graphite electrode is the same as the shape of the photoresist planar structure, and the annealing temperature is greater than or equal to the growth temperature of the diamond.

[0075] Optional, Figure 4 FIG. 1 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention. Figure 4 , a method for preparing a diamond semiconductor device provided by an embodiment of the present invention comprises:

[0076] S101. Provide a diamond substrate.

[0077] S102, spin coating photoresist on one side of the diamond substrate.

[0078] S103, patterning the photoresist to obtain a photoresist planar structure.

[0079] S401, sending the diamond substrate having the photoresist planar structure into an annealing furnace.

[0080] S402, annealing the photoresist planar structure in an atmosphere with a fixed flow rate of inert gas to obtain the graphite electrode.

[0081] Specifically, the inert gas may include nitrogen or argon, etc. Slow annealing may be performed as required, and the annealing temperature is greater than or equal to the growth temperature of diamond to improve the conductivity of the graphite electrode.

[0082] Optional, Figure 5 FIG. 1 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention. Figure 5 , a method for preparing a diamond semiconductor device provided by an embodiment of the present invention comprises:

[0083] S101. Provide a diamond substrate.

[0084] S102, spin coating photoresist on one side of the diamond substrate.

[0085] S103, patterning the photoresist to obtain a photoresist planar structure.

[0086] S401, sending the diamond substrate having the photoresist planar structure into an annealing furnace.

[0087] S501. In the first stage, starting from a starting temperature, the photoresist planar structure is heated to a first intermediate temperature at a preset temperature changing rate for a first preset time in an atmosphere with a fixed flow rate of inert gas.

[0088] S502: In the second stage, the first intermediate temperature is maintained for a second preset time.

[0089] S503 . In the third stage, starting from the first intermediate temperature, the temperature of the photoresist planar structure is raised to a second intermediate temperature at the preset temperature changing rate for the first preset time in an atmosphere with a fixed flow rate of inert gas.

[0090] S504: In the fourth stage, the second intermediate temperature is maintained for a second preset time.

[0091] S505 , in the fifth stage, starting from the second intermediate temperature and continuing at the preset temperature changing rate for the first preset time, the photoresist planar structure is heated to the target temperature in an atmosphere with a fixed flow rate of inert gas.

[0092] S506. In the sixth stage, the target temperature is maintained for a second preset time to obtain the graphite electrode; wherein the first preset time is greater than the second preset time.

[0093] Illustratively, Table 1 is a thermal decomposition annealing process for a photoresist planar structure provided in this embodiment.

[0094]

[0095] Referring to Table 1, Table 1 exemplarily shows that the starting temperature is 20°C, the first intermediate temperature is 300°C, the second intermediate temperature is 600°C, the target temperature is 900°C, the first preset time is 60 minutes, and the second preset time is 30 minutes, without any limitation here.

[0096] In another optional embodiment, the first stage includes a first sub-stage and a second sub-stage located after the first sub-stage; the first preset temperature change rate of the first sub-stage includes a first sub-rate, and the first preset temperature change rate of the second sub-stage includes a second sub-rate; the first sub-rate is less than the second sub-rate; the second sub-rate is less than or equal to the preset temperature change rate of the third stage; the second sub-rate is less than or equal to the preset temperature change rate of the fifth stage.

[0097] Exemplarily, the first sub-stage may be 20 minutes to 50 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes. The first sub-rate may be 5°C / min. The second sub-rate may be 6°C / min. The preset temperature change rate of the third stage may be 7-8°C / min. The preset temperature change rate of the fifth stage may be 10°C / min, which is not limited here.

[0098] In another optional embodiment, the temperature range of the first sub-stage may be a stage corresponding to a temperature starting from 10° C. and increasing to 100° C.-200° C. For example, the temperature range of the first sub-stage may include 20° C.-150° C. The temperature range of the second sub-stage may include 150° C.-300° C.

[0099] This arrangement, on the one hand, allows the photoresist plane structure to be annealed very slowly, H and O in the photoresist plane structure are slowly removed in the first sub-stage, and no warping or other deformation occurs during the process of generating the graphite electrode, ensuring that the shape of the obtained graphite electrode is the same as the shape of the photoresist plane structure. On the other hand, in the second sub-stage and the subsequent second to sixth stages, the efficiency of manufacturing the graphite electrode can be improved, reducing the production cost.

[0100] Optionally, the second preset time is half of the first preset time; the temperature difference between the first intermediate temperature and the second intermediate temperature is equal to the temperature difference between the target temperature and the second intermediate temperature; the target temperature range includes 800°C to 1100°C.

[0101] Specifically, such an arrangement allows the photoresist plane structure to be slowly annealed, and no warping or other deformation occurs during the process of generating the graphite electrode, ensuring that the shape of the obtained graphite electrode is the same as the shape of the photoresist plane structure, thereby improving the yield of the production. The target temperature range includes 800°C to 1100°C, and preferably, the target temperature may include 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C or 1100°C, etc., without any limitation herein. The target temperature range includes 800°C to 1100°C, so that the target temperature of annealing during the preparation of the graphite electrode reaches the growth temperature of the diamond, so that the carbon atoms on the surface of the diamond and the carbon atoms in the graphite electrode form a good bond, so that the defects at the interface between the diamond and the graphite electrode are smaller, the interface state defect density is reduced, the interface resistance between the diamond and the graphite electrode is reduced, and the contact performance of the diamond and the graphite electrode is improved, thereby improving the performance of the diamond semiconductor device, reducing power consumption, and improving the detection sensitivity.

[0102] Optional, Figure 6 FIG. 1 is a flow chart of another method for preparing a diamond semiconductor device provided by an embodiment of the present invention. Figure 6 , a method for preparing a diamond semiconductor device provided by an embodiment of the present invention comprises:

[0103] S601, epitaxially growing a diamond film on one side of a polished substrate using microwave plasma chemical vapor deposition technology; wherein the reaction gases are methane and hydrogen, and the gas flow ratio of the methane to the hydrogen is 1:50 to 1:5; the microwave power is 3000W to 6000W, the growth pressure is 30torr to 200torr, and the temperature is 800℃ to 1100℃.

[0104] Specifically, the substrate may include a silicon substrate such as single crystal silicon, a silicon carbide substrate, a sapphire substrate or a diamond substrate, etc., without any limitation here. After the diamond film is polished and cleaned, an AZ positive photoresist may be spin-coated at a speed of 3000 r / min onto the surface of the diamond-formed film using a coating machine, and after pre-baking, exposure, post-baking, development, and hardening, a photoresist plane structure on the surface of the diamond-formed film is obtained.

[0105] S102, spin coating photoresist on one side of the diamond substrate.

[0106] S103, patterning the photoresist to obtain a photoresist planar structure.

[0107] S104, annealing the photoresist planar structure to obtain a graphite electrode; wherein the shape of the graphite electrode is the same as the shape of the photoresist planar structure, and the annealing temperature is greater than or equal to the growth temperature of the diamond.

[0108] Optional, Figure 7 FIG. 1 is a schematic diagram of a process for preparing a diamond semiconductor device according to an embodiment of the present invention. Figure 7 , provide a single crystal silicon substrate, and make a diamond film on one side of the single crystal silicon substrate to form a diamond substrate 10. Spin-coat a photoresist 20 on one side of the diamond substrate 10. Pattern the photoresist 20 to obtain a photoresist planar structure 30. Send the diamond substrate 10 with the photoresist planar structure 30 into an annealing furnace. Anneal the photoresist planar structure 30 in an atmosphere with a fixed flow of inert gas to obtain the graphite electrode 40.

[0109] Specifically, since the photoresist releases water vapor and organic gas during the pyrolysis process, the width of the graphite electrode formed after pyrolysis will be reduced to a certain extent compared to the width of the photoresist after the photolithography process.

[0110] Optionally, based on the above embodiments, the thickness of the diamond film ranges from 0.1 μm to 50 μm; the thickness of the graphite electrode ranges from 30 nm to 500 nm; and the material of the photoresist includes phenolic resin.

[0111] Exemplarily, microwave plasma chemical vapor deposition (MPCVD) technology is used to heterogeneously grow diamond films on substrates. The MPCVD technology is used to grow diamond films on polished p-type (111) substrates. The reaction gases are methane and hydrogen. The gas flow ratio can be set to 1:50, the microwave power can be set to 5000W, the growth pressure can be set to 70torr, the temperature is 870°C, the growth time is 9 hours, and the thickness of the diamond film is 10μm. After the diamond film is polished and cleaned, the AZ positive photoresist is spin-coated onto the surface of the diamond film at a speed of 3000r / min using a coating machine. After pre-baking, exposure, post-baking, development, and hardening, the photoresist plane structure on the surface of the diamond film is obtained.

[0112] The diamond film with the structured photoresist is sent to an annealing furnace for photoresist thermal decomposition treatment, that is, the sample is annealed in an atmosphere with a fixed flow of inert gas. The annealing process is divided into six stages, and the specific parameters are shown in Table 1. The above-mentioned photolithography process and annealing process are used to complete the preparation of the graphite electrode on the device surface. The preparation process of the graphite electrode is as follows Figure 7 shown.

[0113] Based on the above high-quality polycrystalline diamond substrate, a graphite electrode was prepared using a preparation method for a diamond semiconductor device.

[0114] Figure 8 is a Raman spectrum of a graphite electrode provided by an embodiment of the present invention. Figure 8 The graphite electrode was characterized by Raman spectroscopy. There was a 1362cm -1 and 1603cm -1 The two characteristic peaks of , compared with the standard card, represent the D peak and G peak of graphite respectively. It can be seen that the technical solution provided in this embodiment successfully realizes the graphite electrode on diamond.

[0115] This embodiment provides a diamond semiconductor device, comprising: a diamond substrate and a graphite electrode disposed on one side of the diamond substrate; wherein the graphite electrode is obtained by patterning the photoresist on one side of the diamond substrate to obtain a photoresist plane structure, and pyrolyzing the photoresist plane structure; the shape of the graphite electrode is the same as the shape of the photoresist plane structure. The diamond semiconductor device provided by this embodiment, including the graphite electrode provided by any of the above embodiments, has the beneficial effects of the graphite electrode provided by any of the above embodiments, which will not be repeated here.

[0116] In an optional implementation, this embodiment provides a diamond semiconductor device, in which a graphite electrode with good ohmic contact is formed on one side of a diamond substrate by spin coating photoresist and patterning, and then pyrolyzing, and the graphite electrode can be used as the source and drain of the diamond semiconductor device.

[0117] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a diamond semiconductor device, characterized in that: include: providing a diamond substrate; Spin coating a photoresist on one side of the diamond substrate; Patterning the photoresist to obtain a photoresist planar structure, wherein the photoresist planar structure is in the form of a thin film; Annealing the photoresist planar structure to obtain a graphite electrode; wherein the shape of the graphite electrode is the same as the shape of the photoresist planar structure, and the annealing temperature is greater than or equal to the growth temperature of the diamond; Annealing the photoresist planar structure to obtain a graphite electrode comprises: Sending the diamond substrate having the photoresist planar structure into an annealing furnace; Annealing the photoresist planar structure in an atmosphere with a fixed flow of inert gas to obtain the graphite electrode; The process of annealing the photoresist planar structure in an atmosphere with a fixed flow rate of inert gas to obtain the graphite electrode comprises: In the first stage, starting from the starting temperature, the temperature of the photoresist planar structure is raised to a first intermediate temperature at a preset temperature changing rate for a first preset time in an atmosphere of an inert gas with a fixed flow rate; In the second stage, the first intermediate temperature is maintained for a second preset time; In the third stage, starting from the first intermediate temperature and continuing at the preset temperature changing rate for the first preset time, the photoresist planar structure is heated to a second intermediate temperature in an atmosphere with a fixed flow rate of inert gas; In the fourth stage, the second intermediate temperature is maintained for a second preset time; In the fifth stage, starting from the second intermediate temperature and continuing at the preset temperature changing rate for the first preset time, the photoresist planar structure is heated to the target temperature in an atmosphere with a fixed flow rate of inert gas; In the sixth stage, the target temperature is maintained for a second preset time to obtain the graphite electrode; wherein the first preset time is greater than the second preset time; The first stage includes a first sub-stage and a second sub-stage located after the first sub-stage; The preset temperature change rate of the first sub-stage includes a first sub-rate, and the preset temperature change rate of the second sub-stage includes a second sub-rate; The first sub-rate is less than the second sub-rate; The second sub-rate is less than or equal to the preset temperature change rate of the third stage; The second sub-rate is less than or equal to the preset temperature change rate of the fifth stage.

2. The method according to claim 1, characterized in that Spin coating a photoresist on one side of the diamond substrate, comprising: A positive photoresist or a negative photoresist is spin-coated on one side of the diamond substrate.

3. The method according to claim 1, characterized in that The step of patterning the photoresist to obtain a photoresist planar structure comprises: After the photoresist is subjected to pre-baking, exposure, post-baking, development and hardening process, a photoresist plane structure arranged on one side of the diamond substrate is obtained.

4. The method according to claim 1, characterized in that: The second preset time is half of the first preset time; The temperature difference between the first intermediate temperature and the second intermediate temperature is equal to the temperature difference between the target temperature and the second intermediate temperature; The target temperature ranges from 800°C to 1100°C.

5. The method according to claim 1, characterized in that The provision of a diamond substrate comprises: A diamond film is epitaxially grown on one side of a polished substrate using microwave plasma chemical vapor deposition technology; The reaction gases are methane and hydrogen, and the gas flow ratio of the methane to the hydrogen is 1:50~1:5; the microwave power is 3000W~6000W, the growth pressure is 30 torr~200 torr, and the temperature is 800℃~1100℃.

6. The method according to claim 1, characterized in that The thickness of diamond film ranges from 0.1 mm to 50 mm; The thickness of the graphite electrode ranges from 30 nm to 500 nm; The material of the photoresist includes phenolic resin.

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