Method for improving quality of seam of large-size single crystal diamond

Abstract

The invention discloses a method for improving the quality of a seam of large-size single crystal diamonds, and relates to the technical field of growth of single crystal diamond materials, the surface of the seam surface of two large-size single crystal diamonds is cleaned, it is confirmed that no other dirt such as dust, grease and the like exists, then the surface of the seam is ground and polished, and then the seam surface of the two large-size single crystal diamonds is obtained. According to the method, ICP etching micro-nano processing is carried out on the surfaces of the joints of the single crystal diamonds, and plasma is used for carrying out chemical reaction and physical corrosion on the surfaces of materials, and the method has the advantages that the ICP etching micro-nano processing is carried out on the surfaces of the joints of the two groups of single crystal diamonds, so that transverse epitaxial growth and seamless connection can be realized when the single crystal diamonds are spliced; according to the method, mechanical polishing and chemical polishing are carried out on the single crystal diamonds, so that the surfaces of the joints of the single crystal diamonds can be smooth and tidy, the single crystal diamonds can be conveniently spliced to be more stable, the two groups of single crystal diamonds are fixed in the reaction chamber to react and grow, and the stability of the quality of the joints of the large-size single crystal diamonds is improved.

Description

Technical Field

[0001] The invention relates to the technical field of single crystal diamond material growth, in particular to a method for improving the quality of large-size single crystal diamond joints. Background Art

[0002] Diamond is known as the "ultimate semiconductor" material because of its excellent mechanical properties, such as large bandgap, large hole and electron mobility, effective radiation resistance, etc. It has faster speed, lower power consumption and higher intrinsic mobility than traditional semiconductors, especially in the future 6G era, deep ultraviolet optoelectronic devices, high-voltage and high-power electronic devices and other fields. It has significant advantages and huge development potential and has become a hot spot of international competition. With the development of semiconductor devices, microelectronics, nuclear energy, aerospace, national defense and military industries, the demand for large-sized single-crystal diamonds is becoming more and more urgent. Natural diamonds are far from meeting people's needs. Therefore, it is hoped that high-quality and large-area single-crystal diamond materials can be prepared by artificial synthesis. However, the preparation of large-sized single-crystal diamonds is still mainly based on homoepitaxial growth. Affected by the growth mechanism, the growth rate is relatively slow. Therefore, the size of the prepared single-crystal diamond needs to be strongly dependent on the size of the natural or high-temperature and high-pressure synthetic single-crystal diamond substrate. In addition, during the growth process, due to the competitive growth of different crystal planes, the side surface will produce a higher defect density during the growth process, as well as the influence of defects such as substrate dislocation inheritance, which cannot meet the needs of the electronic device industry for inch-level wafers. For this reason, scholars have begun to explore the preparation of large-scale, high-quality single-crystal diamonds. Currently, the maximum size of single-crystal diamonds obtained by splicing growth can reach 2 inches. However, the biggest problem faced by the splicing growth method is that there are microscopic height differences and gaps at the joints. In splicing growth, it is difficult to achieve seamless connection due to the obvious interface, which leads to defects such as polycrystallization and high dislocation density at the joints of large-area single-crystal diamonds grown by splicing. The quality is quite different from that of single-crystal diamonds grown epitaxially on the substrate surface, making it difficult to become a truly large-scale, high-quality single-crystal diamond wafer, and unable to meet the preparation of large-scale electronic-grade diamonds.

[0003] The technical difficulties of the splicing method mainly focus on the control of the crystal orientation of the substrate and the control of the microscopic gap at the joints. Since it is difficult to achieve seamless arrangement of the interface during the growth process, the substrate splicing is not tight enough and a slight misalignment will lead to the appearance of subgrain boundaries or even gaps at the joints of large-area single crystal diamonds grown by splicing, causing dislocation defects and stress concentration in this area, seriously affecting the crystal quality and unable to meet the preparation of large-size electronic-grade diamonds. For this reason, we propose a method to improve the quality of the joints of large-size single crystal diamonds. Summary of the invention

[0004] The object of the present invention is to provide a method for improving the quality of large-size single-crystal diamond joints.

[0005] In order to solve the problems raised in the above background technology, the present invention provides the following technical solutions: a method for improving the quality of large-sized single crystal diamond joints, cleaning the joint surfaces of two large-sized single crystal diamonds to confirm that there is no dust, grease or other dirt, then grinding and polishing the joint surfaces, and then performing ICP etching micro-nano processing on the joint surfaces of the single crystal diamonds, using plasma to chemically react and physically corrode the material surface to achieve microstructure processing, and the specific steps are as follows:

[0006] Step 1: Take two single crystal diamonds with a size of 5-8 mm and a thickness of 2-5 mm, clean the side surfaces of the single crystal diamonds, and grind the side surfaces with diamond disc blades of different sizes after drying, so that the joint surfaces of the two single crystal diamonds are smooth and flat and have the same thickness;

[0007] Step 2: polishing the single crystal diamond to the same thickness by mechanical polishing and chemical polishing, and performing acid washing and ultrasonic cleaning on the two single crystal diamonds;

[0008] Step 3: Fix the treated single crystal diamond and put it into the ICP etcher to evenly create defect points on the joint surface. Put the treated single crystal diamond into the sample holder in the reaction chamber, evacuate the chamber, and introduce hydrogen and methane to react and grow for 3-6 hours.

[0009] Step 4: Fix the two groups of single crystal diamonds processed in step 3 in the sample holder in the reaction chamber, evacuate the chamber, introduce hydrogen and methane for reaction growth for 4-12 hours, and obtain large-sized single crystal diamonds.

[0010] As a further solution of the present invention: In the step 1, a disc-shaped blade is generally used for grinding the single crystal diamond. Diamond blades with sizes of W10, W5, and W1 are used for grinding for a total of 2-4 hours, a diamond disc-shaped blade with size W10 is used for grinding for 1 hour, and W5 and W1 diamond blades are used for grinding for 1 hour and 2 hours, respectively. Finally, the joint surface of the two single crystal diamonds is made smooth and flat and the overall thickness is the same.

[0011] As a further solution of the present invention: in the step 2, after the single crystal diamond is polished by mechanical polishing, it is immersed in a chemical polishing agent for polishing for 15-20 minutes, and the chemical polishing agent is mainly prepared by an acidic polishing agent. After the chemical polishing is completed, the single crystal diamond is neutralized and cleaned to remove residual chemicals.

[0012] As a further solution of the present invention: in the step 2, sulfuric acid and nitric acid solutions are used to carry out pickling operation on the single crystal diamond to remove impurities generated during the polishing process.

[0013] As a further solution of the present invention: in the step 2, the single crystal diamond is ultrasonically cleaned for 30-60 minutes using acetone, alcohol and deionized water, which can effectively remove impurities on the surface of the single crystal diamond.

[0014] As a further solution of the present invention: In step three, the reaction chamber is one of the devices used to grow a diamond film on a diamond substrate, and there are also a microwave generator, a gas supply system, a bottom heater and a control system. The equipment can be adjusted according to the specific reaction process. The bottom heater is used to heat the equipment and control the reaction temperature of the equipment.

[0015] As a further solution of the present invention: in the step 3, defect points are made on the joint surfaces of the two groups of single crystal diamonds by an ICP etcher, and hydrogen and methane are introduced into the joints for 1-2 hours under vacuum conditions, the temperature is controlled at 900-1100°C, the pressure is 10-16 kPa, and the flow rate of hydrogen is 150-300 cm 3 / min, the flow rate of methane is 10-35cm 3 / min, so that the defects can be rapidly nucleated, and the flow rates of hydrogen and methane are increased. The flow rate of hydrogen is 150-800cm 3 / min, the flow rate of methane is 10-75cm 3 / min, the temperature is controlled at 1000-1200℃, the pressure is 14-20kPa, and the reaction growth is 4-5h to obtain the epitaxial layer of single crystal diamond.

[0016] As a further solution of the present invention: in the step 4, the two groups of processed single crystal diamonds are fixed in a sample holder so that the joint surfaces of the two groups of single crystal diamonds are closely connected, and the two groups of single crystal diamonds are allowed to react and grow under specific conditions.

[0017] As a further solution of the present invention: in the step 4, after the reaction chamber is evacuated, hydrogen and methane are introduced to allow the single crystal diamond joint surface to react and grow for 30-120 minutes, the temperature is controlled at 900-1100°C, the pressure is 10-16 kPa, and the flow rate of hydrogen is 150-300 cm 3 / min, the flow rate of methane is 10-35cm 3 / min, then increase the flow rate of hydrogen and methane, the flow rate of hydrogen is 150-800cm 3 / min, the flow rate of methane is 10-75cm 3 / min, the temperature is controlled at 1000-1200°C, the pressure is 14-20kPa, and the single crystal diamond joint surface is allowed to react and grow for 2-11 hours to obtain a large-sized single crystal diamond.

[0018] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. The present invention performs ICP etching micro-nano treatment on the surface of the joints of two groups of single crystal diamonds, so that the single crystal diamonds can achieve lateral epitaxial growth and seamless connection when spliced. By mechanically polishing and chemically polishing the single crystal diamonds, the surface of the single crystal diamond joints can be smooth and tidy, which is convenient for splicing and makes it more stable. By fixing the two groups of single crystal diamonds in the reaction chamber to make them react and grow, the stability of the quality of the joints of large-sized single crystal diamonds is improved;

[0020] 2. The present invention performs pickling and ultrasonic cleaning on the single crystal diamond so that it can be connected naturally and smoothly during the splicing process, thereby obtaining a large-sized single crystal diamond with high quality at the joint. The single crystal diamond is subjected to vacuum high-temperature reaction in the reaction chamber, and hydrogen and other gases are injected to accelerate the growth rate of the single crystal diamond joint surface, reduce the time for experimental production of large-sized single crystal diamond, and make the experimental operation more convenient and quick; BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the reaction growth of single crystal diamond in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0023] The present invention provides a method for improving the quality of large-size single crystal diamond joints, and the steps are as follows:

[0024] Step 1: Take two single crystal diamonds with a size of 8 mm and a thickness of 5 mm, clean the side surfaces of the single crystal diamonds, and grind the side surfaces after drying to make the joint surfaces of the two single crystal diamonds smooth and flat and have the same thickness;

[0025] Step 2: polishing the single crystal diamond to the same thickness by mechanical polishing and chemical polishing, and performing acid washing and ultrasonic cleaning on the two single crystal diamonds;

[0026] Step 3: Fix the treated single crystal diamond and put it into the ICP etcher to evenly create defect points on the joint surface. Put the treated single crystal diamond into the sample holder in the reaction chamber, evacuate the chamber, and introduce hydrogen and methane to react and grow for 6 hours.

[0027] Step 4: Fix the two groups of single crystal diamonds processed in step 3 in the sample holder in the reaction chamber, evacuate the chamber, introduce hydrogen and methane for reaction growth for 12 hours, and obtain large-sized single crystal diamonds.

[0028] In one embodiment of the present invention: in the step 1, a disc-shaped blade is generally used for grinding the single crystal diamond. Diamond blades with sizes of W10, W5, and W1 are used for grinding for a total of 4 hours, a diamond disc-shaped blade with size W10 is used for grinding for 1 hour, and W5 and W1 diamond blades are used for grinding for 1 hour and 2 hours, respectively. Finally, the joint surface of the two single crystal diamonds is made smooth and flat and the overall thickness is the same.

[0029] In one embodiment of the present invention: in the step 2, after the single crystal diamond is polished by mechanical polishing, it is immersed in a chemical polishing agent for polishing for 20 minutes, and the chemical polishing agent is mainly composed of an acidic polishing agent. After the chemical polishing is completed, the single crystal diamond is neutralized and cleaned to remove residual chemicals.

[0030] In one embodiment of the present invention: in the step 2, sulfuric acid and nitric acid solutions are used to pickle the single crystal diamond to remove impurities generated during the polishing process.

[0031] In one embodiment of the present invention: in the step 2, the single crystal diamond is ultrasonically cleaned for 45 minutes using acetone, alcohol and deionized water, which can effectively remove impurities on the surface of the single crystal diamond.

[0032] In one embodiment of the present invention: in step three, the reaction chamber is one of the devices used to grow a diamond film on a diamond substrate, and there are also a microwave generator, a gas supply system, a bottom heater and a control system. The equipment can be adjusted according to the specific reaction process, and the bottom heater is used to heat the equipment and control the reaction temperature of the equipment.

[0033] In one embodiment of the present invention: in step 3, defect points are made on the joint surfaces of the two groups of single crystal diamonds by an ICP etcher, and hydrogen and methane are introduced into the joints for 1.5 hours under vacuum conditions, the temperature is controlled at 900-1100°C, the pressure is 10-16 kPa, and the flow rate of hydrogen is 150-300 cm 3 / min, the flow rate of methane is 10-35cm 3 / min, so that the defects can be rapidly nucleated, and the flow rates of hydrogen and methane are increased. The flow rate of hydrogen is 150-800cm 3 / min, the flow rate of methane is 10-75cm 3 / min, the temperature was controlled at 1000-1200°C, the pressure was 14-20kPa, and the reaction growth was carried out for 4.5h to obtain the epitaxial layer of single crystal diamond.

[0034] In one embodiment of the present invention: in the step 4, the two groups of processed single crystal diamonds are fixed in a sample holder so that the joint surfaces of the two groups of single crystal diamonds are closely connected, and the two groups of single crystal diamonds are allowed to react and grow under specific conditions.

[0035] In one embodiment of the present invention, in step 4, after the reaction chamber is evacuated, hydrogen and methane are introduced to allow the single crystal diamond joint surface to react and grow for 120 minutes, the temperature is controlled at 900-1100°C, the pressure is 10-16 kPa, and the flow rate of hydrogen is 150-300 cm 3 / min, the flow rate of methane is 10-35cm 3 / min, then increase the flow rate of hydrogen and methane, the flow rate of hydrogen is 150-800cm 3 / min, the flow rate of methane is 10-75cm 3 / min, the temperature is controlled at 1000-1200°C, the pressure is 14-20kPa, and the single crystal diamond joint surface is allowed to react and grow for 10 hours to obtain a large-sized single crystal diamond.

[0036] The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

[0037] Embodiment 1:

[0038] Take two single crystal diamonds with a size of 8 mm and a thickness of 5 mm, clean the side surfaces of the single crystal diamonds, grind the side surfaces after drying, make the joint surfaces of the two single crystal diamonds smooth and flat and have the same thickness, polish the single crystal diamonds to the same thickness by mechanical polishing and chemical polishing, the polishing time is 20 minutes, pickle the two single crystal diamonds and perform ultrasonic cleaning for 45 minutes, fix the processed single crystal diamonds, and make defects on the joint surfaces by ICP etcher, put the processed single crystal diamonds into the sample holder of the reaction chamber, introduce hydrogen and methane under vacuum conditions for reaction for 1.5 hours, control the temperature at 900-1100°C, the pressure at 10-16 kPa, and the flow rate of hydrogen at 150-300 cm 3 / min, the flow rate of methane is 10-35cm 3 / min, so that the defects can be rapidly nucleated, and the flow rates of hydrogen and methane are increased. The flow rate of hydrogen is 150-800cm 3 / min, the flow rate of methane is 10-75cm 3 / min, the temperature is controlled at 1000-1200℃, the pressure is 14-20kPa, and the reaction growth is 4.5h to obtain the epitaxial layer of single crystal diamond;

[0039] After the reaction chamber is evacuated, hydrogen and methane are introduced to allow the single crystal diamond joint surface to react and grow for 120 minutes. The temperature is controlled at 900-1100°C, the pressure is 10-16 kPa, and the flow rate of hydrogen is 150-300 cm 3 / min, the flow rate of methane is 10-35cm 3 / min, then increase the flow rate of hydrogen and methane, the flow rate of hydrogen is 150-800cm 3 / min, the flow rate of methane is 10-75cm 3 / min, the temperature is controlled at 1000-1200℃, the pressure is 14-20kPa, and the single crystal diamond joint surface is allowed to react and grow for 10 hours to obtain a large-sized single crystal diamond. Figure 1 This is a picture of single crystal diamond growing in the reaction chamber.

[0040] Embodiment 2:

[0041] Take two single crystal diamonds with a size of 8 mm and a thickness of 4 mm, clean the side surfaces of the single crystal diamonds, grind the side surfaces after drying, make the joint surfaces of the two single crystal diamonds smooth and flat and have the same thickness, polish the single crystal diamonds to the same thickness by mechanical polishing and chemical polishing, the polishing time is 20 minutes, pickle and ultrasonically clean the two single crystal diamonds for 45 minutes, fix the processed single crystal diamonds, and make defects on the joint surfaces by ICP etcher, put the processed single crystal diamonds into the sample holder of the reaction chamber, introduce hydrogen and methane under vacuum conditions for 1 hour, control the temperature at 900-1100°C, the pressure at 10-16 kPa, and the flow rate of hydrogen at 150-300 cm 3 / min, the flow rate of methane is 10-35cm 3 / min, so that the defects can be rapidly nucleated, and the flow rates of hydrogen and methane are increased. The flow rate of hydrogen is 150-800cm 3 / min, the flow rate of methane is 10-75cm 3 / min, the temperature is controlled at 1000-1200℃, the pressure is 14-20kPa, and the reaction growth is 5h to obtain the epitaxial layer of single crystal diamond;

[0042] After the reaction chamber is evacuated, hydrogen and methane are introduced to allow the single crystal diamond joint surface to react and grow for 120 minutes. The temperature is controlled at 900-1100°C, the pressure is 10-16 kPa, and the flow rate of hydrogen is 150-300 cm 3 / min, the flow rate of methane is 10-35cm3 / min, then increase the flow rate of hydrogen and methane, the flow rate of hydrogen is 150-800cm 3 / min, the flow rate of methane is 10-75cm 3 / min, the temperature is controlled at 950-1150°C, the pressure is 14-20kPa, and the single crystal diamond joint surface is allowed to react and grow for 11 hours to obtain a large-sized single crystal diamond.

[0043] Embodiment three:

[0044] Take two single crystal diamonds with a size of 8 mm and a thickness of 5 mm, clean the side surfaces of the single crystal diamonds, grind the side surfaces after drying, make the joint surfaces of the two single crystal diamonds smooth and flat and have the same thickness, polish the single crystal diamonds to the same thickness by mechanical polishing and chemical polishing, the polishing time is 20 minutes, apply a thin layer of adhesive on the side surface of the single crystal diamond, butt the two single crystal diamonds together through the sample holder to ensure that they are completely fitted without gaps, put the butt-jointed single crystal diamonds into a special fixture, apply appropriate pressure to fully cure the adhesive, finely process the spliced ​​single crystal diamonds, and grind them to the required shape and size to obtain large-sized single crystal diamonds.

[0045] Comparing Example 1 and Example 3, under normal circumstances, the quality strength of the joints achieved by splicing single crystal diamonds using adhesives is much lower than the quality strength of the joints achieved by splicing single crystal diamonds using MPCVD (microwave plasma chemical vapor deposition). This method significantly improves the quality of the joints of large-size single crystal diamonds.

[0046] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

[0047] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0048] The above contents are merely examples and explanations of the present invention. Various modifications or additions to the specific embodiments described or replacements in similar ways by technicians in the technical field shall fall within the protection scope of the present invention as long as they do not deviate from the invention or exceed the scope defined by the claims.

[0049] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for improving the quality of large-size single crystal diamond joints, characterized in that: Clean the joint surfaces of two large-sized single-crystal diamonds to make sure there is no dust, grease or other dirt. Then, grind and polish the joint surfaces, and then perform ICP etching micro-nano processing on the joint surfaces of single-crystal diamonds. Use plasma to chemically react and physically corrode the surface of the material to achieve microstructure processing. The specific steps are as follows: Step 1: Take two single crystal diamonds with a size of 5-8 mm and a thickness of 2-5 mm, clean the side surfaces of the single crystal diamonds, and grind the side surfaces after drying to make the joint surfaces of the two single crystal diamonds smooth and flat and have the same thickness; Step 2: polishing the single crystal diamond to the same thickness by mechanical polishing and chemical polishing, and performing acid washing and ultrasonic cleaning on the two single crystal diamonds; Step 3: Fix the treated single crystal diamond and put it into the ICP etcher to evenly create defect points on the joint surface. Put the treated single crystal diamond into the sample holder in the reaction chamber, evacuate the chamber, and introduce hydrogen and methane to react and grow for 3-6 hours. Step 4: Fix the two groups of single crystal diamonds processed in step 3 in the sample holder in the reaction chamber, evacuate the chamber, introduce hydrogen and methane for reaction growth for 4-12 hours, and obtain large-sized single crystal diamonds.

2. A method for improving the quality of large-size single crystal diamond joints according to claim 1, characterized in that: In the step 1, a disc-shaped blade is generally used for grinding the single crystal diamond. Diamond blades with sizes of W10, W5, and W1 are used for grinding for 2-4 hours, respectively, so that the joint surfaces of the two single crystal diamonds are smooth and flat and the overall thickness is the same.

3. The method for improving the quality of large-size single crystal diamond joints according to claim 1, characterized in that: In the step 2, after the single crystal diamond is polished by mechanical polishing, it is immersed in a chemical polishing agent for polishing for 15-20 minutes. After the chemical polishing is completed, the single crystal diamond is neutralized and cleaned to remove residual chemicals.

4. The method for improving the quality of large-size single crystal diamond joints according to claim 1, characterized in that: In the step 2, the single crystal diamond is pickled using sulfuric acid and nitric acid solutions to remove impurities generated during the polishing process.

5. The method for improving the quality of large-size single crystal diamond joints according to claim 1, characterized in that: In the step 2, acetone, alcohol and deionized water are used to perform ultrasonic cleaning on the single crystal diamond, which can effectively remove impurities on the surface of the single crystal diamond.

6. A method for improving the quality of large-size single crystal diamond joints according to claim 1, characterized in that: In step three, the reaction chamber is one of the devices used to grow a diamond film on a diamond substrate, and also includes a microwave generator, a gas supply system, a bottom heater and a control system, and the equipment can be adjusted according to the specific reaction process.

7. The method for improving the quality of large-size single crystal diamond joints according to claim 1, characterized in that: In the step three, defect points are created on the joint surfaces of the two groups of single crystal diamonds by using an ICP etcher, and hydrogen and methane are introduced under vacuum conditions for 1-2 hours to react so that the defects are rapidly nucleated. Then, the flow rates of hydrogen and methane are increased and the reaction growth is carried out for 4-5 hours to obtain an epitaxial layer of single crystal diamond.

8. The method for improving the quality of large-size single crystal diamond joints according to claim 1, characterized in that: In the step 4, the two groups of processed single crystal diamonds are fixed in a sample holder so that the joint surfaces of the two groups of single crystal diamonds are closely connected, and the two groups of single crystal diamonds are allowed to react and grow under specific conditions.

9. The method for improving the quality of large-size single crystal diamond joints according to claim 1, characterized in that: In the step 4, after the reaction chamber is evacuated, hydrogen and methane are introduced to allow the single crystal diamond joint surface to react and grow for 30-120 minutes, and then the flow rate of hydrogen and methane is increased to allow the single crystal diamond joint surface to react and grow for 2-11 hours to obtain a large-sized single crystal diamond.

Images