Method for manufacturing double-sided diamond and double-sided diamond
By preparing diamond seeds on both the upper and lower surfaces of the substrate and growing diamonds using an annular hollow heat dissipation fixture, the warping problem caused by the difference in thermal expansion coefficients was solved, achieving uniform and flat preparation of double-sided diamonds and improving the stability of the material.
Patent Information
- Application Number
- CN202211246733.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-12
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2042-10-12
AI Technical Summary
In the prior art, the difference in thermal expansion coefficients between the silicon substrate and the epitaxial diamond material causes warping, which may lead to diamond cracking and make it difficult to prepare epitaxial diamond materials with uniform and flat surfaces.
Diamond seeds were prepared on both the upper and lower surfaces of the substrate, and diamonds were grown in a diamond growth furnace using a heat dissipation fixture with an annular hollow structure. By controlling the gas contact surface and temperature changes, the stress balance of the diamonds on the upper and lower surfaces was ensured, and warping was avoided.
This method achieves a uniform and flat surface on both sides of the diamond, avoiding cracking caused by warping and improving the preparation quality and reliability of diamond materials.
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Figure CN115637492B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of diamond preparation technology, and in particular to a method for preparing double-sided diamond and the double-sided diamond itself. Background Technology
[0002] Among known natural substances, diamond has the highest thermal conductivity, reaching 2000 W / m at room temperature. · As can be seen from K, diamond has great application potential in the field of thermal conductivity and heat dissipation, specifically in the heat dissipation of power devices and circuits.
[0003] In existing technologies, silicon substrates are often used to prepare silicon epitaxial diamond materials. This involves preparing a diamond seed on a single crystal plane of the silicon substrate, and then growing the diamond material on that crystal plane. However, since the thermal expansion coefficient of the silicon substrate is greater than that of the epitaxial diamond, the silicon substrate shrinks more during the cooling process, while the diamond material shrinks less. This causes the epitaxial diamond material and the silicon substrate to warp, and in severe cases, the diamond may crack. Summary of the Invention
[0004] This invention provides a method for preparing double-sided diamond and a double-sided diamond, so as to prepare an epitaxial diamond material with a uniform and flat surface.
[0005] In a first aspect, embodiments of the present invention provide a method for preparing double-sided diamond, comprising:
[0006] Diamond seeds were prepared on both the upper and lower surfaces of the substrate to obtain the first composite substrate;
[0007] The heat dissipation fixture is placed on the molybdenum support inside the diamond growth furnace. The heat dissipation fixture has an annular hollow structure and holes that penetrate the side wall of the heat dissipation fixture.
[0008] The first composite substrate is placed on a heat dissipation fixture, the door of the diamond growth furnace is closed, and diamonds are grown on both sides of the first composite substrate to obtain double-sided diamonds.
[0009] In one possible implementation, the heat dissipation fixture is made of high-temperature resistant ceramic material;
[0010] The high-temperature resistant ceramic material is at least one of the following: boron nitride, zirconium dioxide, aluminum oxide, silicon carbide, and boron carbide.
[0011] In one possible implementation, the cross-section of the hole is at least one of the following shapes: circular, elliptical, square, and rectangular.
[0012] In one possible implementation, the holes are evenly distributed on the sidewall of the heat dissipation fixture.
[0013] In one possible implementation, the substrate is a silicon substrate or a molybdenum substrate;
[0014] Before preparing diamond seeds on both the upper and lower surfaces of the substrate, the process also includes:
[0015] The substrate was cleaned sequentially with deionized water and acetone.
[0016] The substrate was dried using a nitrogen gun and then placed in a dustproof device.
[0017] Under preset drying conditions, the dustproof device is placed in the drying oven for drying to obtain a substrate for preparing corundum seeds.
[0018] In one possible implementation, a first composite substrate is placed on a heat dissipation fixture, the door of the diamond growth furnace is closed, and diamond is grown on both sides of the first composite substrate to obtain double-sided diamond, including:
[0019] The first composite substrate is placed on a heat dissipation fixture, the door of the diamond growth furnace is closed, hydrogen is continuously supplied into the diamond growth furnace, the microwave power source is turned on, and when the furnace temperature and furnace pressure meet the preset conditions, gaseous carbon source is continuously supplied into the diamond growth furnace for diamond growth.
[0020] When the time for conveying the gaseous carbon source reaches the first preset time, the conveying of the gaseous carbon source is stopped, and the furnace temperature and furnace pressure are reduced.
[0021] If the current furnace temperature drops to the preset temperature, turn off the microwave power source, stop supplying hydrogen, and turn on the diamond growth furnace to obtain double-sided diamond.
[0022] In one possible implementation, when the furnace temperature and pressure meet preset conditions, a gaseous carbon source is continuously supplied to the diamond growth furnace for diamond growth, including:
[0023] When the furnace temperature reaches 800℃ and the furnace pressure is 100mbar-200mbar, a gaseous carbon source is continuously supplied into the diamond growth furnace.
[0024] The furnace temperature is maintained at 800℃-1000℃ and the furnace pressure at 100mbar-200mbar for diamond growth.
[0025] In one possible implementation, the hydrogen flow rate is 400 sccm;
[0026] The gaseous carbon source is at least one of the following: methane, ethane, ethylene, acetylene, and propane;
[0027] The ratio of the flow rate of the gaseous carbon source to the flow rate of the hydrogen is 5%.
[0028] In one possible implementation, when the time for conveying the gaseous carbon source reaches a first preset time, the conveying of the gaseous carbon source is stopped, including:
[0029] When the time for supplying the gaseous carbon source is 10-100 hours, stop supplying the gaseous carbon source.
[0030] The preset temperature is 20℃-25℃.
[0031] In a second aspect, embodiments of the present invention provide a double-sided diamond, which is prepared by a method as described in the first aspect or any possible implementation thereof.
[0032] This invention provides a method for preparing double-sided diamond. By preparing diamond seeds on both the upper and lower surfaces of a substrate, subsequent diamond growth on both surfaces is facilitated. A heat dissipation fixture, an annular hollow structure with holes penetrating its sidewalls, is placed on a molybdenum support within a diamond growth furnace. The first composite substrate is placed on the heat dissipation fixture, allowing subsequently supplied gas to contact the lower surface of the first composite substrate through the holes in the sidewalls. This ensures that both the upper and lower surfaces of the first composite substrate are in contact with the gas, enabling simultaneous diamond growth on both surfaces. Simultaneous diamond growth on both the upper and lower surfaces ensures consistent stress on the first composite substrate during cooling after diamond formation, achieving stress balance and maintaining overall warpage balance, resulting in a uniform and flat surface of the final diamond. Attached Figure Description
[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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 effort.
[0034] Figure 1 This is a flowchart illustrating the implementation of the method for preparing double-sided diamond provided in this embodiment of the invention.
[0035] Figure 2 This is a schematic diagram of the heat dissipation fixture provided in an embodiment of the present invention;
[0036] Figure 3 This is an application implementation diagram of the method for preparing double-sided diamond provided in the embodiments of the present invention;
[0037] Figure 4This is a schematic diagram of the structure of the double-sided diamond provided in an embodiment of the present invention. Detailed Implementation
[0038] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.
[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.
[0040] Figure 1 The implementation flowchart of the method for preparing double-sided diamond provided in the embodiments of the present invention is described in detail below:
[0041] Step S101: Prepare diamond seeds on both the upper and lower surfaces of the substrate to obtain the first composite substrate.
[0042] In this embodiment, diamond seeds are prepared on both the upper and lower surfaces of the substrate to facilitate the subsequent growth of diamonds on the upper and lower surfaces of the substrate based on the prepared diamond seeds.
[0043] Specifically, diamond seeds are prepared on both the upper and lower surfaces of the substrate, which can be done on a single crystal plane on the upper surface and a single crystal plane on the lower surface of the substrate.
[0044] Step S102: Place the heat dissipation fixture on the molybdenum support inside the diamond growth furnace. The heat dissipation fixture has an annular hollow structure and holes penetrating the side wall of the heat dissipation fixture.
[0045] In this embodiment, a heat dissipation fixture is placed on a molybdenum support, and then the first composite substrate is placed on the annular hollow heat dissipation fixture, so that there is space for diamond growth below the first composite substrate; and the gas subsequently delivered can pass through the holes in the penetrating sidewall of the heat dissipation fixture, so that diamond can also be grown on the lower surface of the first composite substrate; in addition, the first composite substrate and the molybdenum support do not directly contact each other, which can avoid the temperature of the surface of the first composite substrate dropping too quickly, so that diamond can grow at the required temperature.
[0046] Step S103: Place the first composite substrate on the heat dissipation fixture, close the door of the diamond growth furnace, and grow diamonds on both sides of the first composite substrate to obtain double-sided diamonds.
[0047] In this embodiment, the first composite substrate is placed on a heat dissipation fixture for double-sided diamond growth. This allows diamond to be grown simultaneously on the upper and lower surfaces of the first composite substrate. During the cooling process after obtaining the diamond, the stress exerted on the first composite substrate by the diamond on the upper and lower surfaces is consistent, forming a stress balance and maintaining the overall warpage balance, thereby resulting in a uniform and flat surface of the final diamond.
[0048] This invention provides an embodiment where diamond seeds are prepared on both the upper and lower surfaces of a substrate, facilitating subsequent diamond growth on both surfaces. A heat dissipation fixture, an annular hollow structure with holes penetrating its sidewalls, is placed on a molybdenum support within the diamond growth furnace. The first composite substrate is placed on this fixture, allowing subsequently supplied gas to pass through the holes and contact the lower surface of the substrate. This ensures that both the upper and lower surfaces of the first composite substrate are in contact with the gas, enabling simultaneous diamond growth on both surfaces. Simultaneous diamond growth on both surfaces ensures consistent stress distribution during cooling after diamond formation, maintaining overall warpage balance and resulting in a uniformly flat surface on the final diamond.
[0049] In one possible implementation, the heat dissipation fixture is made of a high-temperature resistant ceramic material; the high-temperature resistant ceramic material is at least one of the following: boron nitride, zirconium dioxide, aluminum oxide, silicon carbide, and boron carbide.
[0050] In this embodiment, the heat dissipation fixture is made of high-temperature resistant ceramic material, which can avoid damage to the structure of the heat dissipation fixture during high-temperature diamond growth, and ensure that the heat dissipation fixture can always support the substrate, thereby successfully growing diamond on the lower surface of the substrate. Furthermore, the selection of high-temperature resistant ceramic material can make the structure of the heat dissipation fixture stable, and the heat dissipation fixture can be repeatedly used for diamond preparation, which can save the cost of diamond preparation.
[0051] In one possible implementation, the cross-section of the hole is at least one of the following shapes: circular, elliptical, square, and rectangular.
[0052] In this embodiment, the cross-section of the hole is at least one of the following shapes: circular, elliptical, square, and rectangular, or other shapes; the hole on the sidewall of a heat dissipation fixture can be one of the above shapes, or a combination of several of the above shapes; see attached figure for details. Figure 2 The schematic diagram of the heat dissipation fixture shown shows that the cross-section of the hole in the side wall of one heat dissipation fixture is circular, and the cross-section of the hole in the side wall of the other heat dissipation fixture is rectangular, with the short side of the rectangle being arc-shaped.
[0053] In one possible implementation, the holes are evenly distributed on the sidewall of the heat dissipation fixture.
[0054] In this embodiment, the holes are evenly arranged on the sidewall of the heat dissipation fixture, which can ensure that gas can enter the space under the substrate evenly through the holes during diamond growth, thereby ensuring that the diamond under the substrate can grow evenly.
[0055] In one possible implementation, the substrate is a silicon substrate or a molybdenum substrate.
[0056] In one possible implementation, before preparing the diamond seeds on both the upper and lower surfaces of the substrate, the method further includes: cleaning the substrate sequentially with deionized water and acetone; drying the substrate with a nitrogen gun and placing the dried substrate into a dustproof device; and drying the dustproof device in an oven under preset drying conditions to obtain the substrate for preparing the diamond seeds.
[0057] In this embodiment, before preparing diamond seeds on both the upper and lower surfaces of the substrate, the substrate is cleaned and dried to obtain a clean substrate for preparing diamond seeds. This ensures that diamonds can be grown uniformly on the surface of the substrate, avoiding diamond growth failure due to foreign matter.
[0058] In one possible implementation, see Figure 3 The diagram illustrates the application of a method for preparing double-sided diamond. In this diagram, 31 is a molybdenum support, 32 is a heat dissipation fixture, 33 is a first composite substrate, and 34 is plasma. The first composite substrate 33 is placed on the heat dissipation fixture 32, the door of the diamond growth furnace is closed, and diamond is grown on both sides of the first composite substrate to obtain double-sided diamond, including:
[0059] The first composite substrate 33 is placed on a heat dissipation fixture, the door of the diamond growth furnace is closed, and hydrogen is continuously supplied into the diamond growth furnace. The flow rate of the hydrogen can be 400 sccm. The microwave power source is turned on, and plasma 34 is formed on the surface of the substrate. When the furnace temperature and furnace pressure meet the preset conditions, a gaseous carbon source is continuously supplied into the diamond growth furnace for diamond growth.
[0060] In this embodiment, when the furnace temperature reaches 800°C and the furnace pressure is 100-200 mbar, a gaseous carbon source is continuously supplied to the diamond growth furnace; and the furnace temperature is maintained at 800°C-1000°C and the furnace pressure at 100-200 mbar. The supplied hydrogen is used as the carrier gas, and the supplied gaseous carbon source is used as the growth source for diamond growth. Further, the gaseous carbon source is at least one of the following: methane, ethane, ethylene, acetylene, and propane, and the ratio of the flow rate of the gaseous carbon source to the flow rate of hydrogen is 5%.
[0061] When the time for conveying the gaseous carbon source reaches the first preset time, the conveying of the gaseous carbon source is stopped, and the furnace temperature and furnace pressure are reduced.
[0062] Specifically, when the time for supplying the gaseous carbon source is 10-100 hours, the supply of the gaseous carbon source should be stopped.
[0063] In this embodiment, the diamond growth time can be 10 hours to 100 hours. When the first preset time is reached, that is, after the diamond growth is completed, the carbon source can be stopped. In addition, when the gaseous carbon source is stopped, the furnace pressure and furnace temperature should be reduced slowly to avoid the diamond surface cracking due to sudden contraction of the diamond and the substrate.
[0064] If the current furnace temperature drops to the preset temperature, turn off the microwave power source, stop supplying hydrogen, and turn on the diamond growth furnace to obtain double-sided diamond.
[0065] Furthermore, the preset temperature is room temperature, specifically 20℃-25℃. When the temperature inside the furnace drops to the preset temperature, it indicates that the double-sided diamond has been prepared and the diamond and substrate will no longer shrink. At this point, the diamond growth furnace can be opened to obtain the final double-sided diamond.
[0066] In one specific embodiment, a 2-inch silicon substrate with a thickness of 2 mm is selected. Diamond seeds are grown on both the upper and lower surfaces of the silicon substrate to obtain a composite substrate. The composite substrate is placed on a boron nitride heat dissipation fixture with circular holes inside a diamond growth furnace. The door of the diamond growth furnace is closed, and hydrogen is continuously supplied into the diamond growth furnace at a flow rate of 400 sccm. A microwave power source is turned on to form plasma on the surface of the substrate. When the furnace temperature is 800°C and the furnace pressure is between 100 mbar and 200 mbar, a gaseous carbon source is continuously supplied into the diamond growth furnace to maintain the furnace temperature at 850°C and the furnace pressure at 150 mbar. The ratio of the flow rate of the gaseous carbon source to the flow rate of hydrogen is 5%, and diamond growth is carried out for 50 hours. The supply of gaseous carbon source is stopped, and the furnace temperature and pressure are slowly reduced. When the furnace temperature drops to 23°C, the microwave power source is turned off, the supply of hydrogen is stopped, and the diamond growth furnace is opened to obtain double-sided diamonds.
[0067] The final double-sided diamond sample was tested using digital vernier calipers. The test results showed that the average thickness of the epitaxial diamond on the upper surface of the silicon substrate was 50 μm, and the average thickness of the epitaxial diamond on the lower surface of the silicon substrate was 40 μm. The warpage of the final double-sided diamond sample was less than 20 μm.
[0068] This invention provides an embodiment where diamond seeds are prepared on both the upper and lower surfaces of a substrate, facilitating subsequent diamond growth on these surfaces. A heat dissipation fixture is placed on a molybdenum support, and then the first composite substrate is placed on the annular hollow structure of the heat dissipation fixture, creating space for diamond growth beneath the first composite substrate. Furthermore, the supplied gas can pass through holes in the penetrating sidewalls of the heat dissipation fixture, allowing both the upper and lower surfaces of the first composite substrate to contact the gas, enabling simultaneous diamond growth on both surfaces. Additionally, the first composite substrate does not directly contact the molybdenum support, preventing a rapid drop in surface temperature and ensuring diamond growth at the required temperature. The heat dissipation fixture is made of high-temperature resistant ceramic material, preventing damage during high-temperature diamond growth. The structure of the heat dissipation fixture is disrupted, ensuring that it can consistently support the substrate, thus enabling successful diamond growth on the lower surface of the substrate. Furthermore, the selection of high-temperature resistant ceramic materials stabilizes the structure of the heat dissipation fixture, allowing for repeated use in diamond preparation and reducing costs. Placing the first composite substrate on the heat dissipation fixture and simultaneously growing diamond on both its upper and lower surfaces, followed by a slow reduction of furnace pressure and temperature after diamond formation, prevents sudden contraction of the diamond and substrate, which could cause surface cracking. This ensures consistent stress distribution on the first composite substrate from both the upper and lower surfaces, achieving stress balance and maintaining overall warpage balance, resulting in a uniform and flat surface for the final diamond.
[0069] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
[0070] The following are structural embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.
[0071] Figure 4 A schematic diagram of the structure of a double-sided diamond provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below:
[0072] A double-sided diamond is prepared using the double-sided diamond preparation method described in any of the above embodiments.
[0073] Specifically, 41 represents diamond grown on the upper surface of the substrate, 42 represents the substrate, and 43 represents diamond grown on the lower surface of the substrate.
[0074] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.
Claims
1. A method for preparing double-sided diamond, characterized in that, include: Diamond seeds were prepared on both the upper and lower surfaces of the substrate to obtain the first composite substrate; The heat dissipation fixture is placed on the molybdenum support inside the diamond growth furnace. The heat dissipation fixture has an annular hollow structure and holes penetrating the side wall of the heat dissipation fixture are provided. The holes are evenly distributed on the side wall of the heat dissipation fixture. The first composite substrate is placed on the heat dissipation fixture, the door of the diamond growth furnace is closed, and diamonds are grown simultaneously on the upper and lower surfaces of the first composite substrate to obtain double-sided diamonds.
2. The method for preparing double-sided diamond according to claim 1, characterized in that, The heat dissipation fixture is made of high-temperature resistant ceramic material; The high-temperature resistant ceramic material is at least one of the following: boron nitride, zirconium dioxide, aluminum oxide, silicon carbide, and boron carbide.
3. The method for preparing double-sided diamond according to claim 1, characterized in that, The cross-section of the hole is at least one of the following shapes: circular, elliptical, square, and rectangular.
4. The method for preparing double-sided diamond according to claim 1, characterized in that, The substrate is a silicon substrate or a molybdenum substrate; Before preparing diamond seeds on both the upper and lower surfaces of the substrate, the process also includes: The substrate was cleaned sequentially with deionized water and acetone. The substrate was dried using a nitrogen gun and then placed in a dustproof device. Under preset drying conditions, the dustproof device is placed in an oven for drying to obtain a substrate for preparing corundum seeds.
5. The method for preparing double-sided diamond according to claim 1, characterized in that, The step of placing the first composite substrate on the heat dissipation fixture, closing the door of the diamond growth furnace, and simultaneously growing diamonds on the upper and lower surfaces of the first composite substrate to obtain double-sided diamonds includes: The first composite substrate is placed on the heat dissipation fixture, the door of the diamond growth furnace is closed, hydrogen is continuously supplied into the diamond growth furnace, the microwave power source is turned on, and when the furnace temperature and furnace pressure meet the preset conditions, gaseous carbon source is continuously supplied into the diamond growth furnace for diamond growth. When the time for conveying the gaseous carbon source reaches the first preset time, the conveying of the gaseous carbon source is stopped, and the furnace temperature and furnace pressure are reduced. If the current furnace temperature drops to the preset temperature, the microwave power source is turned off, the hydrogen supply is stopped, the diamond growth furnace is turned on, and the double-sided diamond is obtained.
6. The method for preparing double-sided diamond according to claim 5, characterized in that, The step of continuously supplying a gaseous carbon source into the diamond growth furnace for diamond growth when the furnace temperature and pressure meet preset conditions includes: When the temperature inside the furnace reaches 800°C and the pressure inside the furnace is 100mbar-200mbar, a gaseous carbon source is continuously supplied into the diamond growth furnace. The furnace temperature is maintained at 800℃-1000℃ and the furnace pressure is 100 mbar-200 mbar for diamond growth.
7. The method for preparing double-sided diamond according to claim 5, characterized in that, The flow rate of the hydrogen gas is 400 sccm; The gaseous carbon source is at least one of the following: methane, ethane, ethylene, acetylene, and propane; The ratio of the flow rate of the gaseous carbon source to the flow rate of the hydrogen is 5%.
8. The method for preparing double-sided diamond according to claim 5, characterized in that, When the time for conveying the gaseous carbon source reaches a first preset time, the conveying of the gaseous carbon source is stopped, including: When the time for supplying the gaseous carbon source is 10 hours to 100 hours, the supply of the gaseous carbon source shall be stopped. The preset temperature is 20℃-25℃.
Citation Information
Patent Citations
Method for producing CVD diamond film substantially free of thermal stress-induced cracks
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