Preparation method for reducing defects of monocrystal diamond
By using a high proportion of hydrogen and carbon dioxide etching treatment during the growth process of single crystal diamond, combined with a growth preparation method that controls the gas ratio and temperature, the problem of high dislocation density in microwave plasma chemical gas phase method is solved, and the effect of reducing dislocation density and improving crystal quality is achieved.
Patent Information
- Application Number
- CN202510203254.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2025-05-13
AI Technical Summary
When the single crystal diamond is grown by microwave plasma chemical vapor phase, the temperature gradient leads to thermal stress, the ratio of carbon source and hydrogen affects the growth rate and mass, substrate defects and contamination affects the growth of single crystals, microwave instability leads to energy fluctuations, and increases dislocation density.
The flow ratio of H2 and CO2 is (95-99): (5-1), which is dissociated into active atoms H and O under the action of plasma to remove impurities and defects on the surface of the seed crystal. During the growth process, the flow ratio of carbon source gas, CO2, H2, tin source and inert gas is controlled, the growth temperature, pressure and time are adjusted, and tin is introduced as a surfactant to reduce stress and inhomogeneity. After thermal annealing, pickling and fluorination are carried out to remove impurities and dislocation structures.
Effectively remove impurities and defects on the surface of seed crystals, reduce stress and inhomogeneity during growth, reduce dislocation density, and improve the crystal quality and performance of single crystal diamonds.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of semiconductor devices, and in particular to a preparation method for reducing defects in single crystal diamond. Background Art
[0002] Diamond has excellent optical, thermal, electrical and mechanical properties, and is an ideal wide bandgap semiconductor material that can be used in optics, medicine, detectors and semiconductors. At present, the output of natural diamond is limited, and the preparation methods of artificial diamond are mainly high temperature and high pressure method (HPHT method) and MPCVD method (microwave plasma chemical vapor method). Among them, the impurity control and product size of the high temperature and high pressure method (HPHT method) are not advantageous. Therefore, the preparation method of single crystal diamond used for semiconductor materials is mainly microwave plasma chemical vapor method.
[0003] The main problems of microwave plasma chemical vapor method are: the temperature gradient generated by microwave plasma may cause thermal stress inside the single crystal, thereby inducing dislocations. The proportion of components such as carbon source and hydrogen in the reaction gas may affect the growth rate and quality of diamond, resulting in a decrease in growth rate and an increase in dislocations. Defects or contamination on the surface of the substrate may act as a dislocation source, affecting the growth of single crystal diamond. The instability of microwave plasma may cause energy fluctuations during the growth process, thereby affecting the crystallization quality of diamond. Too short a growth time or inappropriate pressure in the reaction chamber may cause the diamond crystal to fail to grow fully, thereby increasing the dislocation density.
[0004] Therefore, single crystal diamond grown using microwave plasma chemical vapor method has the risk of high dislocation density. Summary of the invention
[0005] In order to reduce the dislocation density of single crystal diamond, the present application provides a preparation method for reducing defects in single crystal diamond.
[0006] The present application provides a method for preparing single crystal diamond with reduced defects, which adopts the following technical solution:
[0007] A preparation method for reducing single crystal diamond defects comprises the following steps:
[0008] Seed crystal etching treatment: Place the seed crystal in the MPCVD growth equipment, introduce H2, CO2 and plasma to etch the seed crystal;
[0009] Preparation of single crystal diamond growth: introducing carbon source gas, CO2, H2, tin source and inert gas into MPCVD growth equipment, wherein the carbon source gas contains CH4, CO2, H2, tin source and inert gas in a flow ratio of (10-20):(300-400):(1-5):(1-3):(1-5), growing the etched seed crystal; the growth temperature is 800-1200°C, the growth pressure is 100-200mbar, the growth time is 100-120h, and a grown diamond is obtained;
[0010] Thermal annealing post-treatment: The grown diamond is placed in a vacuum environment at 800-1200°C for high temperature annealing for 50-80 minutes to obtain single crystal diamond and complete the preparation.
[0011] By adopting the above technical solution, H2 and CO2 are introduced during the seed crystal etching preparation process, and dissociated into active atoms H and O under the action of plasma. The active atoms H and O interact with the carbon atoms of the diamond surface defects to form different CdCyHx complexes. Then, through the interaction of atomic H and CdCyHx complexes, impurities and defects on the seed crystal surface can be effectively removed, providing a purer starting point for subsequent single crystal growth. During the growth preparation process, CO2 increases the growth rate; Sn and carbon atoms have the same valence electrons, and the atomic diameter of Sn is much larger than the atomic diameter of C. This size difference helps prevent Sn atoms from being incorporated into the SiC lattice, thereby maintaining the role of Sn as a surfactant, which can reduce the ability of the diamond surface and help form a smooth surface, thereby improving the crystal quality of single crystal diamond. By controlling the gas ratio, temperature, pressure and growth time during the growth process within the above range, the growth environment of single crystal diamond can be further optimized. The flow ratio of carbon source gas, CO2, H2, tin source and inert gas is within the above range, which helps to provide stable growth conditions, reduce stress and non-uniformity during the growth process, and thus reduce the dislocation density. In particular, the introduction of tin may help to regulate the energy distribution during the growth process and further reduce the formation of dislocations. In the post-processing process, by annealing the grown diamond in a vacuum environment and at high temperature, the stress and defects inside the crystal can be further eliminated, thereby reducing the dislocation density. High temperature annealing helps to rearrange atoms and make the crystal structure more perfect. Therefore, the preparation method of the present application can reduce the dislocation density of single crystal diamond.
[0012] In a specific implementation scheme, before the seed crystal etching step, the seed crystal is pre-treated as follows: the seed crystal is placed in aqua regia, heated to 60-80°C in a water bath, ultrasonically cleaned for 20-40 minutes, and then ultrasonically treated with acetone and anhydrous ethanol alternately for 10-30 minutes, dried, and the pre-treatment is completed.
[0013] By adopting the above technical scheme, before the seed crystal etching treatment step, aqua regia is used for water bath heating and ultrasonic cleaning, which can effectively remove metal impurities and oxides on the surface of the seed crystal, thereby ensuring the cleanliness of the seed crystal surface. Organic contamination and residual aqua regia on the surface of the seed crystal and in the micropores can be further removed by alternating ultrasonic treatment with acetone and anhydrous ethanol. This alternating treatment method can ensure a more thorough cleaning effect and provide better conditions for subsequent seed crystal etching and single crystal diamond growth preparation. Drying removes moisture from the surface of the seed crystal to prevent unnecessary chemical reactions or affect the treatment effect during subsequent treatment. This pre-treatment method can improve the purity and cleanliness of the seed crystal, reduce the impact of impurities and contaminants on the subsequent preparation process, and help improve the quality and performance of single crystal diamond.
[0014] In a specific implementation scheme, in the seed crystal etching process step, the flow ratio of H2 and CO2 is (95-99):(5-1).
[0015] By adopting the above technical solution, a high proportion of hydrogen plays a major role in cleaning and etching during the etching process. The active hydrogen decomposed from hydrogen can effectively react with carbon atoms on the surface of the seed crystal to form gaseous hydrocarbons, thereby removing impurities and amorphous carbon on the surface and providing a pure substrate for subsequent single crystal growth. A small amount of carbon dioxide plays an auxiliary role in the etching process. The introduction of carbon dioxide can fine-tune the chemical properties of the etching environment, which helps to more accurately control the etching rate and depth. In addition, under the above gas ratio, carbon dioxide can synergize with hydrogen to form a reaction environment that is more conducive to etching, which helps to reduce excessive damage to the seed crystal during the etching process and minimize damage to the seed crystal.
[0016] In a specific embodiment, in the seed crystal etching step, the etching temperature is 600-1000° C., the etching pressure is 70-90 Torr, and the etching time is 30 min-2 h.
[0017] By adopting the above technical solution, the above etching temperature helps to promote the chemical reaction and improve the etching efficiency. Within this temperature range, the etchant can react more effectively with the carbon atoms on the surface of the seed crystal, thereby accelerating the removal of impurities and amorphous carbon on the surface. The above temperature can also avoid unnecessary thermal damage to the seed crystal and ensure the quality of the seed crystal after etching. The appropriate etching pressure helps to maintain a stable etching environment. Within the above pressure range, the etchant can be evenly distributed on the surface of the seed crystal to ensure the uniformity and consistency of the etching. Within the above time range, the etchant has enough time to react with the impurities and amorphous carbon on the surface of the seed crystal and remove them. At the same time, avoiding too long etching time can reduce excessive damage to the seed crystal and maintain the integrity and performance of the seed crystal.
[0018] In a specific embodiment, in the single crystal diamond growth preparation step, the tin source is tin tetrachloride, diethyltin or dimethyltin.
[0019] By adopting the above technical solutions, these tin sources can provide a stable flow of tin atoms and have high volatility, which makes it possible to smoothly control the input amount of tin during the growth process, thereby achieving fine control of the growth rate and quality of diamonds. These tin sources have good activity in chemical reactions and can effectively promote chemical reactions during the growth of diamonds and improve growth efficiency. The use of these tin sources can also reduce the growth temperature and energy consumption to a certain extent, making the entire growth process more environmentally friendly and economical.
[0020] In a specific embodiment, in the single crystal diamond growth preparation step, the inert gas is argon or helium.
[0021] By adopting the above technical solution, argon and helium are both gases with extremely stable chemical properties. They will not react chemically with other substances in the single crystal diamond growth process, thereby ensuring the purity of the growth environment. During the growth of single crystal diamond, argon and helium can effectively transfer heat and help maintain the temperature uniformity in the growth furnace, thereby ensuring that the single crystal diamond can grow uniformly and stably. The low density of argon and helium helps to reduce airflow disturbances during the growth process, providing a more stable environment for the growth of single crystal diamond and reducing the generation of growth defects.
[0022] In a specific embodiment, in the single crystal diamond growth preparation step, the concentration of CH4 in the carbon source gas is 4%-8%.
[0023] By adopting the above technical solution, within the above CH4 concentration range, carbon atoms can be deposited on the surface of the seed crystal at a moderate speed, thereby ensuring the uniformity and consistency of the growth of single crystal diamond. This can avoid structural defects and stress accumulation caused by excessive growth rate, and reduce the introduction of impurities, thereby helping to improve the purity of single crystal diamond. Within the above CH4 concentration range, carbon atoms can be arranged more orderly on the surface of the seed crystal, forming a more compact and uniform crystal structure, which helps to improve the hardness and wear resistance of single crystal diamond. Therefore, controlling the concentration of CH4 in the carbon source gas to 4%-8% can effectively maintain a stable growth rate, reduce the introduction of impurities and optimize the crystal structure and performance of diamond.
[0024] In a specific possible implementation scheme, in the post-treatment step of thermal annealing, the obtained single crystal diamond is placed in aqua regia, heated to 60-80°C in a water bath, and ultrasonically cleaned for 5-10 minutes. The single crystal diamond is then placed in a fluorinating agent solution, heated to 60-80°C in a water bath, and ultrasonically cleaned for 5-10 minutes. The single crystal diamond is rinsed to complete the preparation.
[0025] By adopting the above technical solutions, pickling can help remove impurities and attachments on the surface of single crystal diamond, and at the same time, help dissolve or weaken some of the dislocation structures that have been generated. Fluorination helps to change the electronic structure and chemical bonding state of the diamond surface, thereby weakening some of the dislocation structures that have been formed.
[0026] In summary, this application has the following beneficial effects:
[0027] 1. The method of the present application can remove impurities and defects on the surface of the seed crystal, reduce stress and non-uniformity during the growth process, reduce the formation of dislocations, eliminate stress and defects inside the crystal, and thus reduce dislocation density.
[0028] 2. The method of the present application adopts a flow ratio of H2 and CO2 of (95-99):(5-1). Carbon dioxide can work synergistically with hydrogen to form a reaction environment that is more conducive to etching, which helps to reduce excessive damage to the seed crystal during the etching process and minimize damage to the seed crystal.
[0029] 3. The method of the present application, by performing pickling and fluorination treatment after thermal annealing, can remove impurities and attachments on the surface of the single crystal diamond, and at the same time, help to dissolve or weaken some of the generated dislocation structures. DETAILED DESCRIPTION
[0030] The present application is further described in detail below in conjunction with embodiments and comparative examples.
[0031] Example
[0032] Example 1
[0033] This embodiment provides a preparation method for reducing defects in single crystal diamond, comprising the following steps:
[0034] The diamond seed crystal was placed in the MPCVD growth equipment, and the vacuum chamber of the MPCVD growth equipment was first evacuated, and then H2, CO2 and plasma were introduced, and the flow ratio (sccm) of hydrogen and CO2 was controlled at 97:3 to etch the seed crystal. The etching temperature was 800°C, the pressure was 80 Torr, and the etching time was 1.2h. After the etching was completed, the plasma was stopped.
[0035] Then, CH4, CO2, H2, tin tetrachloride and argon are introduced into the MPCVD growth device, and the flow ratio (sccm) of CH4, CO2, H2, tin tetrachloride and argon is maintained at 15:350:3:2:3, and the etched seed crystal is grown. Moreover, during the growth process, the volume concentration of CH4 in the MPCVD growth device is controlled at 4-8%, the growth temperature is 1000°C, the growth pressure is 150mbar, and the growth time is 110h. After the growth of the diamond is completed, the introduction of CH4, CO2, H2, tin tetrachloride and argon is stopped.
[0036] The vacuum chamber of the MPCVD growth equipment is evacuated to vacuum, the temperature in the vacuum chamber of the MPCVD growth equipment is maintained at 1000°C, and the grown diamond is allowed to stand in the vacuum chamber of the MPCVD growth equipment for 65 minutes to complete high-temperature annealing to obtain single crystal diamond, thus completing the preparation.
[0037] Example 2
[0038] The only difference between this embodiment and Embodiment 1 is that the flow ratio (sccm) of CH4, CO2, H2, tin tetrachloride and argon is maintained at 10:400:1:1:1 to grow the etched seed crystal.
[0039] Example 3
[0040] The only difference between this embodiment and embodiment 1 is that the flow ratio (sccm) of CH4, CO2, H2, tin tetrachloride and argon is maintained at 20:300:5:3:5 to grow the etched seed crystal.
[0041] Example 4
[0042] The only difference between this embodiment and embodiment 1 is that the growth temperature is 800° C., the growth pressure is 200 mbar, and the growth time is 120 h.
[0043] Example 5
[0044] The only difference between this embodiment and embodiment 1 is that the growth temperature is 1200° C., the growth pressure is 100 mbar, and the growth time is 100 h.
[0045] Example 6
[0046] The only difference between this embodiment and Embodiment 1 is that the vacuum chamber of the MPCVD growth equipment is evacuated to vacuum, the temperature in the vacuum chamber of the MPCVD growth equipment is maintained at 800°C, and the grown diamond is left to stand in the vacuum chamber of the MPCVD growth equipment for 80 minutes to complete high-temperature annealing to obtain single crystal diamond, thereby completing the preparation.
[0047] Example 7
[0048] The only difference between this embodiment and Embodiment 1 is that the vacuum chamber of the MPCVD growth equipment is evacuated to vacuum, the temperature in the vacuum chamber of the MPCVD growth equipment is maintained at 1200°C, and the grown diamond is left to stand in the vacuum chamber of the MPCVD growth equipment for 50 minutes to complete high-temperature annealing to obtain single crystal diamond, thereby completing the preparation.
[0049] Example 8
[0050] The only difference between this embodiment and embodiment 1 is that H2, CO2 and plasma are introduced, the flow ratio (sccm) of hydrogen and CO2 is controlled at 93:7, and the seed crystal is etched.
[0051] Example 9
[0052] The only difference between this embodiment and embodiment 1 is that H2, CO2 and plasma are introduced, the flow ratio (sccm) of hydrogen and CO2 is controlled at 95:5, and the seed crystal is etched.
[0053] Example 10
[0054] The only difference between this embodiment and embodiment 1 is that H2, CO2 and plasma are introduced, the flow ratio (sccm) of hydrogen and CO2 is controlled at 99:1, and the seed crystal is etched.
[0055] Embodiment 11
[0056] The only difference between this embodiment and embodiment 1 is that H2, CO2 and plasma are introduced, and the flow ratio (sccm) of hydrogen and CO2 is controlled at 99.5:0.5 to etch the seed crystal.
[0057] Example 12
[0058] The only difference between this embodiment and embodiment 1 is that argon gas is replaced by an equal amount of helium gas.
[0059] Embodiment 13
[0060] The only difference between this embodiment and embodiment 1 is that tin tetrachloride is replaced by an equal amount of diethyltin.
[0061] Embodiment 14
[0062] The only difference between this embodiment and embodiment 1 is that tin tetrachloride is replaced by an equal amount of dimethyltin.
[0063] Embodiment 15
[0064] The only difference between this embodiment and embodiment 1 is that the diamond seed crystal is pre-treated as follows: the diamond seed crystal is placed in aqua regia, heated to 70°C in a water bath, ultrasonically cleaned for 30 minutes, and then ultrasonically treated with acetone and anhydrous ethanol alternately for 20 minutes, dried, and the pre-treatment is completed before the diamond seed crystal is placed in the MPCVD growth equipment.
[0065] Example 16
[0066] The only difference between this embodiment and embodiment 1 is that the diamond seed crystal is pre-treated as follows: the diamond seed crystal is placed in aqua regia, heated to 60°C in a water bath, ultrasonically cleaned for 40 minutes, and then ultrasonically treated with acetone and anhydrous ethanol alternately for 30 minutes, dried, and the pre-treatment is completed before the diamond seed crystal is placed in the MPCVD growth equipment.
[0067] Embodiment 17
[0068] The only difference between this embodiment and embodiment 1 is that the diamond seed crystal is pre-treated as follows: the diamond seed crystal is placed in aqua regia, heated to 80°C in a water bath, ultrasonically cleaned for 20 minutes, and then ultrasonically treated with acetone and anhydrous ethanol alternately for 10 minutes, dried, and the pre-treatment is completed before the diamond seed crystal is placed in the MPCVD growth equipment.
[0069] Embodiment 18
[0070] The only difference between this embodiment and embodiment 1 is that the obtained single crystal diamond is placed in aqua regia, heated to 60°C in a water bath, ultrasonically cleaned for 10 minutes, and then placed in a hydrofluoric acid solution with a mass concentration of 30%, heated to 60°C in a water bath, ultrasonically cleaned for 10 minutes, and rinsed to complete the preparation.
[0071] Embodiment 19
[0072] The only difference between this embodiment and embodiment 1 is that the obtained single crystal diamond is placed in aqua regia, heated to 70°C in a water bath, ultrasonically cleaned for 7 minutes, and then placed in a hydrofluoric acid solution with a mass concentration of 30%, heated to 70°C in a water bath, ultrasonically cleaned for 7 minutes, and rinsed to complete the preparation.
[0073] Embodiment 20
[0074] The only difference between this embodiment and embodiment 1 is that the obtained single crystal diamond is placed in aqua regia, heated to 80°C in a water bath, ultrasonically cleaned for 10 minutes, and then placed in a hydrofluoric acid solution with a mass concentration of 30%, heated to 80°C in a water bath, ultrasonically cleaned for 10 minutes, and rinsed to complete the preparation.
[0075] Embodiment 21
[0076] The difference between this embodiment and embodiment 1 is that the diamond seed crystal is pre-treated as follows: the diamond seed crystal is placed in aqua regia, heated to 70°C in a water bath, ultrasonically cleaned for 30 minutes, and then ultrasonically treated with acetone and anhydrous ethanol for 20 minutes alternately, dried, and the pre-treatment is completed, and then the diamond seed crystal is placed in the MPCVD growth equipment. The obtained single crystal diamond is placed in aqua regia, heated to 60°C in a water bath, ultrasonically cleaned for 10 minutes, and then placed in a fluorinating agent solution, heated to 6°C in a water bath, ultrasonically cleaned for 10 minutes, and the single crystal diamond is rinsed to complete the preparation.
[0077] Comparative Example
[0078] Comparative Example 1
[0079] The only difference between this comparative example and Example 1 is that the flow ratio (sccm) of CH4, CO2, H2, tin tetrachloride and argon is maintained at 8:450:0.5:0.5:0.5 to grow the etched seed crystal.
[0080] Comparative Example 2
[0081] The only difference between this comparative example and Example 1 is that the flow ratio (sccm) of CH4, CO2, H2, tin tetrachloride and argon is maintained at 25:250:6:6:6 to grow the etched seed crystal.
[0082] Comparative Example 3
[0083] The only difference between this comparative example and Example 1 is that the growth temperature is 600° C., the growth pressure is 250 mbar, and the growth time is 130 h.
[0084] Comparative Example 4
[0085] The only difference between this comparative example and Example 1 is that the growth temperature is 1400° C., the growth pressure is 80 mbar, and the growth time is 90 h.
[0086] Comparative Example 5
[0087] The only difference between this comparative example and Example 1 is that CH4, CO2, H2 and argon are introduced into the MPCVD growth equipment, and the flow ratio (sccm) of CH4, CO2, H2 and argon is maintained at 15:350:3:5 to grow the etched seed crystal.
[0088] Comparative Example 6
[0089] The only difference between this comparative example and Example 1 is that CH4, CO2, tin tetrachloride and argon are introduced into the MPCVD growth equipment, and the flow ratio (sccm) of CH4, CO2 and argon is maintained at 15:350:2:6 to grow the etched seed crystal.
[0090] Comparative Example 7
[0091] The difference between this comparative example and Example 1 is that a preparation method for reducing defects in single crystal diamond comprises the following steps:
[0092] The diamond seed crystal was placed in the MPCVD growth equipment, and the vacuum chamber of the MPCVD growth equipment was first evacuated, and then H2, CO2 and plasma were introduced, and the flow ratio (sccm) of hydrogen and CO2 was controlled at 97:3 to etch the seed crystal. The etching temperature was 800°C, the pressure was 80 Torr, and the etching time was 1.2h. After the etching was completed, the plasma was stopped.
[0093] Then, carbon source gas, CO2, H2, tin tetrachloride and argon are introduced into the MPCVD growth equipment. The carbon source gas contains CH4, and the volume concentration of CH4 in the carbon source gas is 6%. The flow ratio (sccm) of CH4, CO2, H2, tin tetrachloride and argon is maintained at 15:350:3:2:3, and the etched seed crystal is grown. The growth temperature is 1000°C, the growth pressure is 150mbar, and the growth time is 110h. The grown diamond is obtained, and the introduction of CH4, CO2, H2, tin tetrachloride and argon is stopped, and the preparation is completed.
[0094] Performance testing
[0095] The following performance tests were performed on the single crystal diamonds prepared in Examples 1-21 and Comparative Examples 1-7:
[0096] According to T / IAWBS 018-2022 “Test method for dislocation density of diamond single crystal polishing wafer”, the dislocation density of the single crystal diamond prepared in each embodiment and comparative example was tested.
[0097] The growth rate of the single crystal diamond prepared in each embodiment and comparative example was detected.
[0098] The test results are shown in Table 1.
[0099] Table 1
[0100]
[0101]
[0102] Combining Example 1 and Comparative Examples 1-2 and Table 1, it can be seen that compared with Example 1, the dislocation density of Comparative Examples 1-2 is significantly increased, but the growth rate changes slightly. This shows that the method of the present application can reduce the dislocation density of single crystal diamond and maintain a high growth rate within the gas flow ratio range of Examples 1-3.
[0103] Combining Example 1 and Comparative Examples 3-4 and Table 1, it can be seen that the growth rate of Comparative Example 3 is smaller than that of Example 1. The dislocation density of Comparative Example 4 is significantly larger, which shows that the method of the present application can reduce the dislocation density of single crystal diamond under the growth conditions of Example 1 while maintaining a relatively high growth rate.
[0104] Combining Example 1 and Comparative Examples 5-7 and Table 1, it can be seen that the dislocation density and growth rate of Comparative Examples 5-7 are both smaller than those of Example 1. This shows that only with the coordinated cooperation of the gas flow ratio and process steps in Example 1 can the effect of reducing the dislocation density of single crystal diamond and maintaining a high growth rate be achieved.
[0105] Combining Examples 1-14 and Table 1, it can be seen that the dislocation density of Examples 1-14 is 4×10 4 cm -2 , the growth rates are all greater than 0.9 μm / h, which indicates that the dislocation density of single crystal diamond can be reduced by using the process conditions within the range of Examples 1-14.
[0106] Combining Examples 1, 15-21 and Table 1, it can be seen that the dislocation density of Examples 15-21 is significantly reduced compared to Example 1. This shows that the dislocation density of single crystal diamond can be further reduced by using the process conditions within the range of Examples 15-21.
[0107] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.
Claims
1. A method for reducing defects in single crystal diamond, characterized in that: The steps include: Seed crystal etching treatment: Place the seed crystal in the MPCVD growth equipment, introduce H2, CO2 and plasma to etch the seed crystal; Preparation of single crystal diamond growth: introducing carbon source gas, CO2, H2, tin source and inert gas into MPCVD growth equipment, wherein the carbon source gas contains CH4, CO2, H2, tin source and inert gas in a flow ratio of (10-20):(300-400):(1-5):(1-3):(1-5), growing the etched seed crystal; the growth temperature is 800-1200°C, the growth pressure is 100-200mbar, the growth time is 100-120h, and a grown diamond is obtained; Thermal annealing post-treatment: The grown diamond is placed in a vacuum environment at 800-1200°C for high temperature annealing for 50-80 minutes to obtain single crystal diamond and complete the preparation.
2. A method for reducing defects in single crystal diamond according to claim 1, characterized in that: Before the seed crystal etching step, the seed crystal is pre-treated as follows: the seed crystal is placed in aqua regia, heated to 60-80°C in a water bath, ultrasonically cleaned for 20-40 minutes, and then ultrasonically treated with acetone and anhydrous ethanol alternately for 10-30 minutes, dried, and the pre-treatment is completed.
3. A method for reducing defects in single crystal diamond according to claim 1, characterized in that: In the seed crystal etching process, the flow ratio of H2 and CO2 is (95-99):(5-1).
4. A method for reducing defects in single crystal diamond according to claim 3, characterized in that: In the seed crystal etching process, the etching temperature is 600-1000° C., the etching pressure is 70-90 Torr, and the etching time is 30 min-2 h.
5. The method for reducing defects in single crystal diamond according to claim 1, characterized in that: In the single crystal diamond growth preparation step, the tin source is tin tetrachloride, diethyltin or dimethyltin.
6. A method for reducing defects in single crystal diamond according to claim 5, characterized in that: In the single crystal diamond growth preparation step, the inert gas is argon or helium.
7. A method for reducing defects in single crystal diamond according to claim 6, characterized in that: In the single crystal diamond growth preparation step, the concentration of CH4 in the carbon source gas is 4%-8%.
8. The method for preparing single crystal diamond with reduced defects according to claim 1, characterized in that: In the post-treatment step of thermal annealing, the obtained single crystal diamond is placed in aqua regia, heated to 60-80°C in a water bath, ultrasonically cleaned for 5-10 minutes, and then placed in a fluorinating agent solution, heated to 60-80°C in a water bath, ultrasonically cleaned for 5-10 minutes, and rinsed to complete the preparation.