Pre-treatment method of substrate and method for preparing diamond film

Abstract

The application belongs to the field of diamond film preparation, and particularly discloses a substrate pretreatment method and a diamond film preparation method. The substrate pretreatment method comprises the following steps: cleaning the substrate and then drying; placing the substrate into a vacuum chamber, introducing argon, and performing plasma bombardment cleaning on the substrate; performing magnetron sputtering film coating on the substrate, with a time of 10-60 min and a film thickness of about 30-100 nm; placing the treated substrate into a diamond micro-powder / anhydrous ethanol suspension liquid for ultrasonic inoculation; performing ultrasonic cleaning and blowing dry, and standby; and the diamond film preparation method is to deposit diamond on the pretreated substrate obtained by using the above substrate pretreatment method. The application overcomes the shortcomings of mechanical grinding and ordinary ultrasonic inoculation, improves the nucleation rate, density and quality of diamond, and provides a good prerequisite for the growth of high-quality diamond film. In the process of diamond film deposition, the low carbon concentration used further improves the quality of the diamond film.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of diamond film preparation, and particularly relates to a substrate pretreatment method and a diamond film preparation method. BACKGROUND

[0002] The unique crystal structure of diamond determines its numerous excellent physical and chemical properties, and it is a typical multifunctional material, which has good application prospects in many high-tech fields such as energy, catalysis, sensors, precision machining, etc. However, natural diamond has very few reserves and is expensive, and is mostly in the form of particles, which is often used in the field of luxury consumption such as jewelry; diamond prepared by high temperature and high pressure method has many impurities and is difficult to dope, and is mostly in the form of particles, which is mostly used in the field of abrasive mold, and is difficult to meet the actual needs of diamond in high-tech fields.

[0003] Chemical vapor deposition (CVD) is an effective method for preparing high-quality diamond films, and especially microwave chemical vapor deposition (MPCVD) has become the preferred scheme for preparing high-quality diamond films due to its large plasma density and no electrode pollution, etc. However, it is not easy to prepare high-quality diamond films, and the quality is affected by many factors, especially the quality of nucleation directly determines the quality of diamond films. The pretreatment of the substrate is the most common and important method to enhance the nucleation density and quality.

[0004] In the existing method for preparing diamond films, the substrate is often pretreated by mechanical grinding and ultrasonic treatment. These technologies have great randomness, especially mechanical grinding, which is difficult to ensure the consistency of the treatment, resulting in certain differences in the quality of the prepared diamond films, and mechanical grinding is easy to cause the breakage of the substrate, resulting in certain waste. SUMMARY

[0005] In view of the problems in the prior art, the present application aims to provide a substrate pretreatment method.

[0006] Another object of the present application is to provide a method for preparing diamond films.

[0007] In order to achieve the object of the present application, the specific technical solutions are as follows:

[0008] A substrate pretreatment method, comprising the following steps:

[0009] S1. cleaning the substrate, and then drying;

[0010] S2. placing the substrate into a vacuum chamber, introducing argon, and using plasma to bombard and clean the substrate;

[0011] S3. Magnetron sputtering plating is performed on the substrate, a high-purity graphite target is used as the target material, the argon flow is controlled to be 20-100 sccm, the gas pressure is 0.5-2 Pa, the substrate temperature is 50-250 DEG C, the deposition rate is 1-4 nm / min, the time is 10-60 min, and the film thickness is 30-100 nm;

[0012] S4. The treated substrate is placed into a diamond powder / anhydrous ethanol suspension, and ultrasonic inoculation is performed for 10-30 min;

[0013] S5. Ultrasonic cleaning and blow drying are performed, and the substrate is ready for use.

[0014] Preferably, in step S1, the substrate is selected from one of silicon, silicon dioxide and titanium.

[0015] Preferably, in step S1, the cleaning process specifically comprises: first, using deionized water and detergent to remove dust and oil stains on the surface of the substrate, and then using acetone for ultrasonic cleaning for 10-20 min,

[0016] Preferably, in step S2, the argon flow is 5-10 sccm.

[0017] Preferably, in step S4, the solid-liquid ratio of the diamond powder / anhydrous ethanol suspension is 2.5-10 g:100 ml.

[0018] Preferably, in step S5, the ultrasonic cleaning specifically comprises: sequentially using acetone, anhydrous ethanol and deionized water to ultrasonically clean the substrate for 5-15 min.

[0019] The application further discloses a preparation method of a diamond film, which uses the treated substrate obtained by the above-mentioned pretreatment method to deposit diamond.

[0020] Preferably, the deposition atmosphere is hydrogen and methane, the volume ratio of the hydrogen and the methane is 100:1.5-2.5, the deposition pressure is 9-21 kPa, and the deposition temperature is 800-920 DEG C.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] (1) The application innovatively combines the processes of plating and ultrasonic inoculation to pretreat the substrate, a layer of diamond-like carbon film is plated on the surface of the substrate by using the magnetron sputtering plating method before diamond deposition, then the treated substrate is inoculated by ultrasonic, a large amount of diamond powder is inlaid into the surface of the substrate, according to the crystal nucleation theory, these inlaid diamond powders can act as the nucleation crystal nucleus in the nucleation early stage, the nucleation rate is high, and a large amount of defects etched from the substrate can provide high free energy positions required by diamond nucleation, thereby greatly improving the nucleation position density.

[0023] (2) The invention overcomes the shortcomings of mechanical grinding and ordinary ultrasonic inoculation, improves the rate, density and quality of diamond nucleation, and provides a good precondition for the growth of high-quality diamond films. During the deposition of the diamond film, the use of low carbon concentration further improves the quality of the diamond film.

[0024] (3) The process flow of the invention is simple and suitable for large-area industrial promotion. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The process flow chart of the embodiment of the invention.

[0026] Figure 2 The Raman diagram of the diamond film obtained in Example 1 of the invention. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the invention, the invention will be described more fully and specifically below in conjunction with the drawings and preferred embodiments, but the scope of protection of the invention is not limited to the following specific embodiments.

[0028] Unless otherwise defined, all professional terms used herein have the same meaning as generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the invention.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the invention can be purchased from the market or can be prepared by existing methods.

[0030] Example 1

[0031] The present embodiment provides a method for preparing a diamond film, comprising the following steps:

[0032] S1. Single crystal silicon is selected as the substrate, and deionized water and detergent are used to remove dust and oil stains on the surface of the substrate, then acetone is used for ultrasonic treatment for 15 min, and the substrate is dried in an oven after ultrasonic treatment;

[0033] S2. The dried substrate is placed in a vacuum chamber, argon gas is introduced at a flow rate of 5 sccm, and the substrate is bombarded and cleaned by plasma;

[0034] S3. High-purity graphite is used as the target material, argon gas is introduced at a flow rate of 60 sccm, the gas pressure is 0.5 Pa, the sputtering power is 100 W, the substrate temperature is 100℃, the deposition time is 25 min, and the film thickness is about 50 nm.

[0035] S4. The substrate after ultrasonic inoculation is sequentially ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 5 min;

[0036] S5. Put the treated substrate into 5g diamond powder and 100ml anhydrous ethanol for ultrasonic inoculation for 8min;

[0037] S6. Dry the cleaned substrate with dry air for standby;

[0038] S7. Put the dried substrate of step S6 into a microwave plasma chemical vapor deposition device, pass in 200sccm of hydrogen, and when the pressure rises to 2kPa, turn on the microwave, adjust the power and pressure, so that the temperature reading is 850℃, the pressure is 14kPa, pass in 4sccm of methane, and deposit for 20h to obtain a diamond film. Figure 2 As shown in the figure, the prepared sample has a sharp diamond characteristic peak D peak at 1332cm -1 , and no obvious amorphous carbon G peak appears, indicating that the prepared diamond has high quality.

[0039] Example 2

[0040] The embodiment provides a preparation method of a diamond film, comprising the following steps:

[0041] S1. Select a single crystal silicon as a substrate, and first remove dust and oil stains on the surface of the substrate using deionized water and a detergent, and then ultrasonically clean the substrate with acetone for 15min, and dry the substrate in a drying oven after ultrasonic cleaning;

[0042] S2. Put the dried substrate into a vacuum chamber, pass in argon at a flow rate of 5sccm, and clean the substrate by using plasma bombardment;

[0043] S3. Use high-purity graphite as a target material, pass in Ar at a flow rate of 100sccm, the gas pressure is 2Pa, the sputtering power is 100W, the substrate temperature is 100℃, the deposition time is 25min, and the film thickness is about 50nm.

[0044] S4. Ultrasonically clean the substrate after ultrasonic inoculation with acetone, anhydrous ethanol and deionized water in sequence for 5min;

[0045] S5. Put the treated substrate into 5g diamond powder and 100ml anhydrous ethanol for ultrasonic inoculation for 8min;

[0046] S6. Dry the cleaned substrate with dry air for standby;

[0047] S7. Put the dried substrate of step S6 into a microwave plasma chemical vapor deposition device, pass in 200sccm of hydrogen, and when the pressure rises to 2kPa, turn on the microwave, adjust the power and pressure, so that the temperature reading is 850℃, the pressure is 14kPa, pass in 4sccm of methane, and deposit for 20h to obtain a diamond film.

[0048] Comparative Example 1

[0049] The present comparative example provides a method for preparing a diamond film, comprising the following steps:

[0050] S1. Single crystal silicon was selected as the substrate, and deionized water and detergent were used to remove dust and oil stains on the surface of the substrate, followed by ultrasonic treatment with acetone for 15 min, and then drying in an oven;

[0051] S2. The dried substrate was placed in a vacuum chamber, and argon gas was introduced at a flow rate of 5 sccm, and the substrate was bombarded and cleaned by plasma;

[0052] S3. High-purity graphite was used as the target material, argon gas was introduced at a flow rate of 60 sccm, the gas pressure was 5 Pa, the sputtering power was 100 W, the substrate temperature was 100°C, the deposition time was 25 min, and the film thickness was about 50 nm.

[0053] S4. The substrate after ultrasonic inoculation was sequentially ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 5 min;

[0054] S5. The treated substrate was placed in 5 g of diamond micro-powder and 100 ml of anhydrous ethanol for ultrasonic inoculation for 8 min;

[0055] S6. The cleaned substrate was blown dry with dry air for standby use;

[0056] S7. The substrate dried in step S6 was placed in a microwave plasma chemical vapor deposition device, 200 sccm of hydrogen gas was introduced, and when the pressure rose to 2 kPa, the microwave was turned on, the power and pressure were adjusted, the temperature reading was 850°C, the pressure was 14 kPa, 4 sccm of methane was introduced, and the diamond film was deposited for 20 h.

[0057] Comparative Example 2

[0058] The present comparative example provides a method for preparing a diamond film by combining plasma dry etching and ultrasonic inoculation process to pretreat the substrate, comprising the following steps:

[0059] S1. Single crystal silicon was selected as the substrate, and the substrate was sequentially ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water, and then dried;

[0060] S2. The silicon substrate cleaned and dried in step S1 was placed in a microwave plasma chemical vapor deposition system, the door was closed, the vacuum pump was turned on to evacuate the chamber, 400 sccm of oxygen was introduced when the pressure reached 0.01 Pa, the microwave was turned on when the pressure rose to 2 kPa, the power was adjusted to a temperature of 400°C and a pressure of 20 kPa, and etching was performed for 60 min;

[0061] S3. The substrate after step S2 is put into a suspension of 5g, W0.25 diamond powder and 100ml anhydrous ethanol for ultrasonic inoculation for 30min;

[0062] S4. The substrate after ultrasonic inoculation is cleaned with acetone, anhydrous ethanol and deionized water in sequence for 5min, and then the cleaned substrate is dried by blowing;

[0063] S5. The dried substrate after step S4 is put into a chemical vapor deposition system, 200sccm of hydrogen is introduced after the pressure is changed to 0.01Pa, the microwave is turned on when the pressure is increased to 2kPa, the power and pressure are adjusted so that the temperature reading is 850℃ and the pressure is 14kPa, 4sccm of methane is introduced, and the deposition is carried out for 20h to obtain a diamond film.

[0064] Comparative Example 3

[0065] This comparative example provides a method for preparing a diamond film, which uses single crystal silicon as the substrate without pretreatment and directly carries out deposition:

[0066] 200sccm of hydrogen is introduced, the microwave is turned on when the pressure is increased to 2kPa, the power and pressure are adjusted so that the temperature reading is 850℃ and the pressure is 14kPa, 4sccm of methane is introduced, and the deposition is carried out for 20h to obtain a diamond film.

[0067] Test Example

[0068] The pretreated substrates and diamond films obtained in Examples 1 / 2 and Comparative Examples 1 / 2 / 3 are tested in this example, and the obtained data is shown in Table 1. It can be seen that the quality of the diamond film prepared by the method of the present application is excellent.

[0069] Table 1

[0070]

[0071] The above is only the preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the present application.

Claims

1. A method of pretreating a substrate, characterized by, The method comprises the following steps: S1. washing the substrate, and then drying; S2. placing the substrate into a vacuum chamber, introducing argon gas at a flow rate of 5-10 sccm, and performing plasma bombardment cleaning on the substrate; S3. performing magnetron sputtering film deposition on the substrate, using a high-purity graphite target, controlling the argon gas flow rate to be 20-100 sccm, the gas pressure to be 0.5-2 Pa, the substrate temperature to be 50-250 DEG C, the deposition rate to be 1-4 nm / min, the time to be 10-60 min, and the film thickness to be 30-100 nm; S4. placing the treated substrate into a diamond powder / anhydrous ethanol suspension, controlling the solid-liquid ratio of the diamond powder / anhydrous ethanol suspension to be 2.5-10 g:100 ml, and ultrasonic inoculation for 10-30 min; S5. ultrasonic cleaning, blowing dry, and standby.

2. The method of pretreating a substrate according to claim 1, wherein, In step S1, the substrate is selected from one of silicon, silicon dioxide, and titanium.

3. The method of pretreating a substrate of claim 1 wherein, In step S1, the washing process specifically comprises: first removing dust and oil stains on the surface of the substrate by using deionized water and detergent, and then performing ultrasonic treatment with acetone for 10-20 min.

4. The method of pretreating a substrate of claim 1 wherein, In step S5, the ultrasonic cleaning specifically comprises: sequentially performing ultrasonic cleaning on the substrate with acetone, anhydrous ethanol, and deionized water for 5-15 min.

5. A method of producing a diamond film, characterized by, The pretreated substrate obtained by using the pretreatment method of the substrate according to any one of claims 1-4 is used for depositing diamond.

6. The method of claim 5, wherein the substrate is heated to a temperature of 700- 900°C. The deposition atmosphere is hydrogen and methane, the volume ratio of the hydrogen and methane is 100:1.5-2.5, the deposition pressure is 9-21 kPa, and the deposition temperature is 800-920 DEG C.

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