MPCVD monocrystal diamond growth method for defective diamond seed crystals
Through the steps of screening, cutting, cleaning, pretreatment and filling gaps in the MPCVD single crystal diamond growth method, the problem of high-quality single crystal diamond seed crystals being prone to cracks during the growth process is solved, and the growth of high-quality single crystal diamonds is achieved, reducing seed waste and production costs.
Patent Information
- Application Number
- CN202311569851.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-22
- Publication Date
- 2025-05-23
AI Technical Summary
In the prior art, high-quality single crystal diamond seed crystals are prone to cracks during growth, laser cutting and polishing, resulting in a decrease in yield. The seed crystals containing cracks may explode in a high-temperature environment, wasting the seed crystals and increasing production costs.
The MPCVD single crystal diamond growth method is adopted with the steps of screening, cutting, cleaning, pretreatment and filling notches. The cracked area is removed by laser cutting, ultrasonic cleaning removes residues, and the annealing treatment improves the quality of seed crystals. The gap is filled by hydrogen, microwave and gas mixture in the MPCVD equipment to achieve high-quality growth of seed crystals.
Quickly determine and remove the crack-affected area, avoid crack extension and cracking, extend the service life of seed crystals, reduce seed crystal waste and production costs, and ensure the growth of high-quality single crystal diamonds.
Smart Images
Figure CN120026389A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of diamond preparation, and in particular to an MPCVD single crystal diamond growth method for defective diamond seed crystals. Background Art
[0002] Single crystal diamond is an ancient crystal material, usually used to polish into diamonds for jewelry or grinding and cutting materials. However, with the advancement of science and technology, many excellent material properties of single crystal diamond (such as high thermal conductivity, wide electromagnetic wave transmission frequency domain, high carrier mobility, etc.) have been gradually explored, making it an ideal material in the fields of power device heat dissipation, laser windows, wide bandgap semiconductors, etc. Microwave plasma chemical vapor deposition (MPCVD) technology is currently recognized as a way to artificially prepare large-size, high-quality single crystal diamonds. Its growth process is divided into homoepitaxial growth and heteroepitaxial growth according to the different substrates used. Homoepitaxial growth is a method of epitaxial growth using single crystal diamond seed crystals as growth substrates. Due to its high lattice matching and few defects, it has become an effective way to grow large thickness, high-quality single crystal diamonds. In the homoepitaxial method, high-quality single crystal diamond seed crystals are usually separated from the growth products (laser cutting) and polished for reuse after growth is completed due to their high price. However, the seed crystal may be cracked during the growth process, laser cutting process, and polishing process. The cracked seed crystal may expand or even explode due to the high temperature environment during the subsequent growth process, resulting in a decrease in the yield rate. Therefore, an MPCVD single crystal diamond growth method for defective diamond seed crystals is required. After searching, no technical solution identical to the present invention was found. Summary of the invention
[0003] The main technical problem solved by the present invention is to provide an MPCVD single crystal diamond growth method for defective diamond seed crystals, solving one or more of the above-mentioned prior art problems.
[0004] In order to solve the above technical problems, a technical solution adopted by the present invention is: an MPCVD single crystal diamond growth method for defective diamond seed crystals, the innovation of which is: comprising the following steps:
[0005] 1) Screening diamond seed crystals; placing defective single crystal diamond seed crystals under a polarizing microscope, the crack-affected area appears black under orthogonal polarized light, while the non-affected area appears as a light and dark image, thereby determining the crack-affected area and marking the black area;
[0006] 2) Cutting defects: Using laser to cut away the defective area, forming a notch, the side wall of the notch is perpendicular to the upper and lower surfaces of the diamond seed crystal, and the seed crystal with the defect-affected area removed is obtained;
[0007] 3) Cleaning the seed crystal; placing the seed crystal with the defect-affected area removed in an ultrasonic cleaning machine to obtain a cleaned seed crystal;
[0008] 4) pretreating the seed crystal; placing the cleaned seed crystal in a tube furnace, and annealing the seed crystal at a temperature of 550-600° C. in a vacuum atmosphere to obtain an annealed seed crystal;
[0009] 5) Filling the gap; placing the annealed seed crystal in the MPCVD equipment, closing the door to evacuate, introducing hydrogen and turning on the microwave to ignite the plasma, increasing the cabin pressure and microwave input power until the cabin pressure reaches 80-130mbar, the microwave power reaches 1000-1800W, and the seed crystal temperature reaches 700-780°C, introducing methane and nitrogen to make the single crystal diamond grow laterally and fill the gap, wherein the methane content is 18%-25%, and the nitrogen content is 0.001%-0.1%, to obtain a seed crystal after filling treatment;
[0010] 6) Seed crystal growth: turn off nitrogen, reduce methane content, increase seed crystal temperature, carry out vertical epitaxial growth of MPCVD single crystal diamond, and complete the growth of MPCVD single crystal diamond containing cracked seed crystal.
[0011] In some embodiments, in step 2), the notch is triangular in shape, and the side walls of the notch extend from the surface of the diamond seed crystal toward the inside and intersect at the same time.
[0012] In some embodiments, in step 3), the ultrasonic cleaning machine is filled with a cleaning solution, which is a mixed reagent of concentrated sulfuric acid and a hydrogen peroxide solution with a mass concentration of 25-28%, and the cleaning time in step 3) is 2.5-3 hours.
[0013] In some embodiments, the temperature in the tubular furnace in step 4) is increased by 30° C. per second, maintained at the target temperature for 5 seconds, and then decreased by 15° C. per second until the target temperature is reached.
[0014] In some embodiments, step 6) reduces the volume content of methane to 9%-12% and increases the seed crystal temperature to 1200-1300°C.
[0015] The beneficial effects of the present invention are as follows: the present technical solution can quickly determine the crack-affected area and completely remove it, ensuring that the crack does not extend, expand or crack during the subsequent growth process; the present technical solution can gradually grow the notch from the bottom to the top, so that the cracked seed crystal can also be used for high-quality single crystal growth, reducing the waste of seed crystals and lowering production costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:
[0017] Figure 1 The invention relates to the notch shape of the defective diamond seed crystal and the crystal growth process. DETAILED DESCRIPTION
[0018] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0019] like Figure 1 As shown, the embodiment of the present invention includes:
[0020] A method for growing single crystal diamond using MPCVD for a defective diamond seed crystal, the innovation of which is that it comprises the following steps:
[0021] 1) Screening diamond seed crystals; placing defective single crystal diamond seed crystals under a polarizing microscope, the crack-affected area appears black under orthogonal polarized light, while the non-affected area appears as a light and dark image, thereby determining the crack-affected area and marking the black area;
[0022] 2) Cutting defects: Using laser to cut away the defective area, forming a notch, the side wall of the notch is perpendicular to the upper and lower surfaces of the diamond seed crystal, and the seed crystal with the defect-affected area removed is obtained;
[0023] 3) Cleaning the seed crystal; placing the seed crystal with the defect-affected area removed in an ultrasonic cleaning machine to obtain a cleaned seed crystal;
[0024] 4) pretreating the seed crystal; placing the cleaned seed crystal in a tube furnace, and annealing the seed crystal at a temperature of 550-600° C. in a vacuum atmosphere to obtain an annealed seed crystal;
[0025] 5) Filling the gap; placing the annealed seed crystal in the MPCVD equipment, closing the door to evacuate, introducing hydrogen and turning on the microwave to ignite the plasma, increasing the cabin pressure and microwave input power until the cabin pressure reaches 80-130mbar, the microwave power reaches 1000-1800W, and the seed crystal temperature reaches 700-780°C, introducing methane and nitrogen to make the single crystal diamond grow laterally and fill the gap, wherein the methane content is 18%-25%, and the nitrogen content is 0.001%-0.1%, to obtain a seed crystal after filling treatment;
[0026] 6) Seed crystal growth: turn off nitrogen, reduce methane content, increase seed crystal temperature, carry out vertical epitaxial growth of MPCVD single crystal diamond, and complete the growth of MPCVD single crystal diamond containing cracked seed crystal.
[0027] In step 2), the notch is triangular in shape, and the side walls of the notch extend from the surface of the diamond seed crystal to the inside and intersect at the same time.
[0028] In step 3), the ultrasonic cleaning machine is filled with a cleaning solution, which is a mixed reagent of concentrated sulfuric acid and a hydrogen peroxide solution with a mass concentration of 25-28%. The cleaning time in step 3) is 2.5-3 hours.
[0029] The temperature in the tubular furnace in step 4) is raised by 30°C per second, maintained at the target temperature for 5 seconds, and then lowered by 15°C per second until the target temperature is reached.
[0030] In step 5), the door is closed and the vacuum is evacuated to below 5×10-5 mbar, 260 sccm of hydrogen is introduced, and microwaves are turned on to ignite the plasma.
[0031] Step 6) reducing the volume content of methane to 9%-12% and increasing the seed crystal temperature to 1200-1300°C.
[0032] This technical solution can quickly determine the crack-affected area and completely remove it, ensuring that the crack does not extend or crack during the subsequent growth process; this technical solution can gradually grow the bottom of the notch toward the top, so that cracked seed crystals can also be used for high-quality single crystal growth, reducing seed crystal waste and lowering production costs.
[0033] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.
Claims
1. A method for growing single crystal diamond using MPCVD from a defective diamond seed crystal, Features: The steps include: 1) Screening diamond seed crystals; placing defective single crystal diamond seed crystals under a polarizing microscope, the crack-affected area appears black under orthogonal polarized light, while the non-affected area appears as a light and dark image, thereby determining the crack-affected area and marking the black area; 2) Cutting defects: Using laser to cut away the defective area, forming a notch, the side wall of the notch is perpendicular to the upper and lower surfaces of the diamond seed crystal, and the seed crystal with the defect-affected area removed is obtained; 3) Cleaning the seed crystal; placing the seed crystal with the defect-affected area removed in an ultrasonic cleaning machine to obtain a cleaned seed crystal; 4) pretreating the seed crystal; placing the cleaned seed crystal in a tube furnace, and annealing the seed crystal at a temperature of 550-600° C. in a vacuum atmosphere to obtain an annealed seed crystal; 5) Filling the gap; placing the annealed seed crystal in the MPCVD equipment, closing the door to evacuate, introducing hydrogen and turning on the microwave to ignite the plasma, increasing the cabin pressure and microwave input power until the cabin pressure reaches 80-130mbar, the microwave power reaches 1000-1800W, and the seed crystal temperature reaches 700-780°C, introducing methane and nitrogen to make the single crystal diamond grow laterally and fill the gap, wherein the methane content is 18%-25%, and the nitrogen content is 0.001%-0.1%, to obtain a seed crystal after filling treatment; 6) Seed crystal growth: turn off nitrogen, reduce methane content, increase seed crystal temperature, carry out vertical epitaxial growth of MPCVD single crystal diamond, and complete the growth of MPCVD single crystal diamond containing cracked seed crystal.
2. The MPCVD single crystal diamond growth method for a defective diamond seed crystal according to claim 1, Features: In step 2), the notch is triangular in shape, and the side walls of the notch extend from the surface of the diamond seed crystal to the inside and intersect at the same time.
3. The MPCVD single crystal diamond growth method for a defective diamond seed crystal according to claim 1, Features: In step 3), the ultrasonic cleaning machine is filled with a cleaning solution, which is a mixed reagent of concentrated sulfuric acid and a hydrogen peroxide solution with a mass concentration of 25-28%. The cleaning time in step 3) is 2.5-3 hours.
4. The MPCVD single crystal diamond growth method for a defective diamond seed crystal according to claim 1, Features: The temperature in the tubular furnace in step 4) is raised by 30°C per second, maintained at the target temperature for 5 seconds, and then lowered by 15°C per second until the target temperature is reached.
5. The MPCVD single crystal diamond growth method for defective diamond seed crystals according to claim 1, Features: Step 6) reducing the volume content of methane to 9%-12% and increasing the seed crystal temperature to 1200-1300°C.