Silicon carbide insulating substrate based on double-sided aluminum coating and preparation method thereof

Abstract

The invention belongs to the technical field of semiconductors, and particularly relates to a silicon carbide insulating substrate based on double-sided aluminum coating and a preparation method thereof. A first silicon carbide layer, a second silicon carbide layer and a third silicon carbide layer are sequentially arranged on the silicon carbide insulating substrate from top to bottom in the thickness direction of the silicon carbide insulating substrate. A first metal layer is arranged between the first silicon carbide layer and the second silicon carbide layer, and a second metal layer is arranged between the second silicon carbide layer and the third silicon carbide layer; an upper copper layer is arranged on the first silicon carbide layer, and the upper copper layer is provided with an etching position; and a lower copper layer is arranged on the third silicon carbide layer. The three silicon carbide layers are arranged on the silicon carbide insulating substrate, the metal layer is arranged between every two silicon carbide layers, and the thermal stress and junction temperature of the chip can be reduced by using silicon carbide as the insulating layer; the metal layer is arranged on the surface of the silicon carbide insulating layer, thermal stress impact can be reduced, the chip can be prevented from being damaged due to overlarge thermal stress, and the reliability of the module can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductors, and in particular relates to a silicon carbide insulating substrate based on double-sided aluminum coating and a preparation method thereof. Background Art

[0002] In power electronics applications, in order to improve the current carrying capacity of power modules, multiple chips are generally configured into multi-chip packaged power modules. As a multi-chip packaged power module, it is not only required to have excellent electrothermal performance, but also to have good thermomechanical reliability, which determines the service life of the power module. With the continuous reduction in the size of power devices and the increase in power density, the packaging of power modules has become more miniaturized and lightweight. Compared with silicon-based power modules, the junction temperature of power devices in silicon carbide power modules is much higher, and high temperature has become a necessary condition for the operation of power modules. For silicon carbide power devices, due to their high voltage, high temperature and high frequency working characteristics, new challenges have been brought to the packaging and heat dissipation of silicon carbide power modules.

[0003] At present, the substrates used for power modules are mainly divided into resin substrates, ceramic substrates and metal base substrates; among them, the thermal conductivity of resin substrates is 1W / (m·K), and they have poor heat dissipation, heat resistance and reliability, and are usually used for control boards; the thermal conductivity of metal base substrates is about 2W / (m·K)~6W / (m·K), and they are mainly used for power modules rated below 600V / 50A systems; the thermal conductivity of ceramic substrates is 20W / (m·K)~170W / (m·K), and they are often used in high-power and high-current silicon carbide power modules.

[0004] The heat dissipation of the silicon carbide power module package is mainly conducted to the outer shell through the ceramic copper-clad board formed by the copper cladding of the ceramic substrate. Since oxygen-free copper has a high thermal conductivity, the determining factor of the thermal conductivity of the ceramic copper-clad board is the performance of the ceramic substrate material. This type of ceramic substrate has a large thermal resistance due to the pad layer and its welding layer. The inherent difference in thermal expansion coefficient between the ceramic substrate and copper in the ceramic copper-clad board will cause the ceramic copper-clad substrate to be subjected to thermal cycles. Large stress is generated at the copper and ceramic interface, resulting in ceramic cracking or copper layer peeling, which can easily cause the silicon carbide chip to be damaged by excessive thermal stress, causing the silicon carbide power module to fail, becoming the main bottleneck for reducing the thermal resistance of the silicon carbide power module, affecting the environmental reliability of the silicon carbide power module, and restricting the service life of the silicon carbide power module. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a silicon carbide insulating substrate based on double-sided aluminum coating and a preparation method thereof. The present invention is based on an insulating substrate formed by silicon carbide material, which reduces the thermal resistance of the substrate, thereby improving the heat dissipation efficiency of the silicon carbide power module and increasing the operating temperature. At the same time, the silicon carbide material used as the substrate is the same as the silicon carbide chip material, and has the same thermal expansion. A metal layer is plated on the surface of the silicon carbide insulating layer, which can reduce thermal stress impact, prevent the silicon carbide chip from being damaged by excessive thermal stress, and improve the reliability of the silicon carbide power module.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] It should be noted that if it is required to work in a high temperature environment, the power rating of a general silicon carbide power module will be reduced when the temperature is higher than a certain value, that is, the output power will be reduced by 30% when the temperature rises by 20°C. In actual applications, the normal working environment temperature will change due to changes in climate and changes in system operating conditions. The module generally will not continue to operate for a considerable period of time under its specified maximum ambient temperature conditions. If the temperature control of the module limit is appropriate, the module capacity can be limited only at the maximum ambient temperature in most operating conditions, maximizing the power of the module.

[0008] However, high temperature is the main factor affecting the thermal mechanical reliability of power modules. In order to improve the heat dissipation performance of the module, the reliability of the ceramic copper-clad substrate at high temperature is becoming more and more important. Among them, the ceramic copper-clad substrate is a ceramic insulating substrate directly bonded between two layers of copper. These ceramic insulating substrates are usually selected according to the application and their thermal properties, mechanical properties and electrical insulation properties. Common ceramic insulating substrate materials include aluminum oxide, aluminum nitride, silicon nitride, etc. Among them, aluminum oxide is the most economical choice. Although it has relatively high mechanical strength, it is much weaker in thermal conductivity compared with other materials, which is relatively not in line with the development requirements of subsequent power devices; aluminum nitride has higher thermal conductivity and its thermal expansion coefficient is almost the same as that of silicon, which effectively reduces problems such as delamination and solder fatigue, but the mechanical strength is not enough in larger thermal cycles. The thermal expansion coefficient of silicon nitride is also very close to that of semiconductor chips, and it provides good mechanical strength and thermal fatigue resistance, but cost and supply are relatively a "weak point".

[0009] Based on this, on the one hand, the present invention provides a silicon carbide insulating substrate based on double-sided aluminum coating, comprising: Along the thickness direction of the silicon carbide insulating substrate, the silicon carbide insulating substrate is provided with a first silicon carbide layer, a second silicon carbide layer and a third silicon carbide layer in sequence from top to bottom, and the thickness of the first silicon carbide layer, the second silicon carbide layer and the third silicon carbide layer are all 80μm to 120μm; a first metal layer is provided between the first silicon carbide layer and the second silicon carbide layer, and a second metal layer is provided between the second silicon carbide layer and the third silicon carbide layer, and the thickness of the first metal layer and the second metal layer are all 40μm to 60μm.

[0010] An upper copper layer is arranged on the first silicon carbide layer, and the upper copper layer is provided with an etching position; a lower copper layer is arranged on the third silicon carbide layer; the thickness of the upper copper layer and the lower copper layer are both 240 μm to 360 μm.

[0011] The silicon carbide insulating substrate provided by the present invention has three silicon carbide layers arranged on the silicon carbide insulating substrate, and a metal layer is arranged between each silicon carbide layer, that is, the silicon carbide insulating substrate is obtained by alternately arranging the silicon carbide layer and the metal layer. By using silicon carbide as the insulating layer, the thermal stress and junction temperature of the silicon carbide chip can be reduced. At the same time, since the thermal conductivity of silicon carbide as a ceramic layer is better than that of traditional materials, it will not cause the junction temperature of the silicon carbide chip to increase too much; and the metal layer is arranged on the surface of the silicon carbide layer, and the characteristics of its soft texture and good thermal conductivity are utilized, and the thermal stress impact can be reduced at the same time, and the silicon carbide chip can be prevented from being damaged by excessive thermal stress, and the reliability of the silicon carbide rate module can be improved. A silicon carbide insulating substrate is obtained by alternating the silicon carbide layer and the metal layer, and the thickness between the silicon carbide layer and the metal layer is controlled, and the matching of the thermal expansion coefficients of the silicon carbide layer and the metal layer is regulated, thereby shortening the thermal resistance from the power device to the packaging substrate, improving the heat dissipation efficiency of the packaging substrate, and achieving the purpose of quickly reducing the junction temperature of the power device, reducing the thermal resistance of the substrate, thereby improving the heat dissipation efficiency of the silicon carbide module, and increasing the operating temperature of the silicon carbide power module.

[0012] In some embodiments, the first metal layer and the second metal layer are both aluminum metal layers. It should be noted that the present invention uses aluminum metal as the metal layer, and the thermal conductivity is 237W / (m·K)‌‌. Due to the inherent difference in thermal expansion coefficients between ceramic and copper, when the ceramic copper-clad substrate is subjected to thermal cycles, a large stress is generated at the interface between copper and ceramic, resulting in ceramic cracking or copper layer peeling. The present invention uses the silicon carbide layer and the copper layer with similar thermal conductivity, and utilizes its soft texture and good thermal conductivity. It can reduce thermal stress shock, prevent the chip from being damaged by excessive thermal stress, improve the reliability of the module, and the price of aluminum metal is relatively low.

[0013] In some embodiments, a first bonding layer is provided between the first silicon carbide layer and the upper copper layer, a second bonding layer is provided between the third silicon carbide layer and the lower copper layer, the thickness of the first bonding layer and the second bonding layer are both 50nm to 100nm, and the first bonding layer and the second bonding layer are both titanium metal layers. It should be noted that copper particles can be directly plated after sputtering the titanium metal layer, that is, direct copper plating method, which can save process costs.

[0014] The silicon carbide insulating substrate provided by the present invention is made of the same material as the silicon carbide chip, the insulating layer is a three-layer silicon carbide layer, and the thickness between the silicon carbide layer and the metal layer is controlled, and the matching of the thermal expansion coefficients of the silicon carbide layer and the metal layer is regulated to shorten the thermal resistance from the power device to the packaging substrate, improve the heat dissipation efficiency of the packaging substrate, and achieve the purpose of quickly reducing the junction temperature of the power device, reduce the thermal resistance of the substrate, thereby improving the heat dissipation efficiency of the silicon carbide module, and increase the operating temperature of the silicon carbide power module. At the same time, it can reduce thermal stress shock, can withstand more thermal shock tests, can prevent the silicon carbide chip from being damaged by excessive thermal stress, and improve the reliability of the silicon carbide power module.

[0015] On the other hand, the present invention provides a method for preparing the above-mentioned silicon carbide insulating substrate based on double-sided aluminum coating, comprising the following steps: The metal elements are sputtered and deposited on the upper surface and the lower surface of the second silicon carbide layer respectively by sputtering, and the upper surface or the lower surface of the second silicon carbide layer is metalized. Then, the metal elements are deposited by electroplating to a thickness of 40 μm to 60 μm to obtain a first metal layer and a second metal layer respectively.

[0016] Silicon carbide is sputtered and deposited on the upper surface of the first metal layer and the lower surface of the second metal layer respectively by sputtering, and then silicon carbide is deposited to a thickness of 80 μm to 120 μm by chemical vapor deposition to obtain a first silicon carbide layer and a third silicon carbide layer respectively.

[0017] It should be noted that before sputtering and depositing silicon carbide, the upper surface of the first metal layer or the lower surface of the second metal layer needs to be cleaned respectively, and acetone or isopropyl ketone is used to thoroughly clean the aluminum surface to remove dust and other contaminants. After cleaning the surface, the sandblasting method is used to increase the surface roughness of the first metal layer and the second metal layer to increase the contact surface area and enhance the adhesion. After the cleaning is completed, silicon carbide is first sputtered on the first metal layer and the second metal layer, and then high-quality silicon carbide is deposited by chemical vapor deposition to obtain the first silicon carbide layer or the third silicon carbide layer.

[0018] Metal copper is sputtered and deposited on the upper surface of the first silicon carbide layer and the lower surface of the third silicon carbide layer respectively by sputtering, and then metal copper is deposited to a thickness of 240 μm to 360 μm by electroplating deposition to obtain an upper copper layer and a lower copper layer respectively.

[0019] It should be noted that the deposition of metallic copper adopts the direct copper plating method, namely the DPC process. The full name of DPC in English is Direct Plating Copper. It mainly uses surface deposition processes such as evaporation and magnetron sputtering to metallize the substrate surface. First, titanium is sputtered under vacuum conditions, then copper particles, and finally electroplating thickening. Then the circuit is made by ordinary PCB process, and finally the thickness of the circuit is increased by electroplating / chemical plating deposition. Before depositing metallic copper, the first silicon carbide layer or the third silicon carbide layer is cleaned, organic solvents are used to remove impurities, and microscopic particles are cleaned with ultrasound to ensure that there are no pollutants on the surface. The surface of silicon carbide is roughened using a sandblasting process to increase the contact area. After the surface has been treated as above, metallic copper is sputtered and deposited.

[0020] A photoresist is coated on the upper copper layer, and etching is performed to form an etching position, thereby obtaining a silicon carbide insulating substrate based on double-sided aluminum coating.

[0021] It should be noted that the present invention does not specifically limit the sputtering method, electroplating deposition and chemical vapor deposition method, that is, the sputtering process, electroplating deposition and chemical vapor deposition commonly used by personnel in this field are adopted. The sputtering process can make the surface metal uniform and fine and the thickness can be controlled. After the sputtering process is completed, the electroplating deposition method is adopted, wherein the temperature of the chemical vapor deposition is 1000°C to 1200°C, and the reaction gas used in the chemical vapor deposition process is a mixture of hydrogen and monosilane.

[0022] It should be noted that the surface of the upper copper layer is etched. Before etching, the surface is first cleaned, cleaned with acetone or isopropyl ketone to remove organic matter on the surface, and then the surface is cleaned with ultrasound to remove microparticles. Finally, it is dried under a nitrogen environment. After drying, a layer of photoresist is evenly coated on the copper surface. The thickness of the coating is 1μm to 5μm. After coating, the photoresist is pre-dried to remove the solvent in the photoresist and improve its adhesion. The photoresist is exposed through a mask using an ultraviolet light source, and the exposed substrate is placed in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer. Etching can be selected from wet etching and dry etching. Wet etching is wet etching using a chemical etching solution such as a sulfuric acid solution that can dissolve copper materials. This step needs to control the etching time to ensure that only the copper layer not covered by the photoresist is removed; dry etching is dry etching using plasma, and the copper layer is selectively removed by a reaction gas such as chlorine. After the wet etching is completed, the photoresist is removed using acetone, leaving the etched copper layer. Finally, ultrasonic cleaning is performed to obtain a complete silicon carbide insulating substrate.

[0023] In some embodiments, the thickness of the surface metallization is 1 μm to 5 μm. The purpose is to first form a copper layer with controllable thickness and uniform and fine surface metal on the upper and lower surfaces of the second silicon carbide layer, thereby increasing the adhesion and thickness controllability of the metal copper layer.

[0024] In some embodiments, the thickness of the sputter-deposited copper metal is 20 μm to 30 μm. It should be noted that after the sputtering is completed, the surface and adhesion of the copper layer are checked, and electroplating is performed on the sputter-deposited copper layer to a thickness of 300 μm. During the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness.

[0025] In some embodiments, the temperature of chemical vapor deposition is 1000°C to 1200°C, and the reaction gas used in the chemical vapor deposition process is a mixture of hydrogen and monosilane. The deposition rate is controlled by chemical vapor deposition to ensure that a thickness of 100 μm is deposited without damaging the metal layer. After the deposition is completed, annealing is performed and heat treatment is performed in a nitrogen environment to enhance the bonding strength between the materials.

[0026] In some embodiments, after chemical vapor deposition or electroplating deposition is completed, annealing is performed at 150°C to 300°C for 8h to 12h in nitrogen or inert gas. After electroplating is completed, annealing treatment is required in a nitrogen environment at 150°C to 300°C for 8h to 12h to enhance the bonding strength between materials. After annealing, the surface is polished to eliminate surface unevenness and defects.

[0027] Compared with the prior art, the present invention has the following beneficial effects: (4) The silicon carbide insulating substrate provided by the present invention has a first silicon carbide layer, a second silicon carbide layer and a third silicon carbide layer arranged in sequence from top to bottom along the thickness direction of the silicon carbide insulating substrate; a first metal layer is arranged between the first silicon carbide layer and the second silicon carbide layer, and a second metal layer is arranged between the second silicon carbide layer and the third silicon carbide layer, that is, three silicon carbide layers are arranged on the silicon carbide insulating substrate, and a metal layer is arranged between each silicon carbide layer. Silicon carbide is used as an insulating layer to reduce the thermal stress and junction temperature of the silicon carbide chip. At the same time, since the thermal conductivity of silicon carbide as a ceramic layer is better than that of traditional materials, it will not cause the junction temperature of the silicon carbide chip to rise too much. The metal layer arranged on the surface of the insulating layer can reduce thermal stress shock by utilizing its soft texture and good thermal conductivity, thereby preventing the silicon carbide chip from being damaged by excessive thermal stress and improving the reliability of the power module. The present invention obtains a silicon carbide insulating substrate by alternately arranging silicon carbide layers and metal layers, controls the thickness between the silicon carbide layer and the metal layer, regulates the matching of the thermal expansion coefficients of the silicon carbide layer and the metal layer, thereby shortening the thermal resistance from the power device to the packaging substrate, improving the heat dissipation efficiency of the packaging substrate, achieving the purpose of quickly reducing the junction temperature of the power device, reducing the thermal resistance of the substrate, thereby improving the heat dissipation efficiency of the silicon carbide module, and increasing the operating temperature of the silicon carbide power module.

[0028] (2) The present invention provides a method for preparing a silicon carbide insulating substrate, which comprises sputtering and depositing metal elements on the upper surface or the lower surface of the second silicon carbide layer to form a first metal layer or a second metal layer, and depositing the first metal layer or the second metal layer to form a first silicon carbide layer or a third silicon carbide layer, and then sputtering and depositing metal copper, and etching to form an etching position to obtain a silicon carbide insulating substrate based on double-sided aluminum coating, wherein the surface metal is uniform and fine, the thickness is controllable, the adhesion performance is good, and the reliability of the insulating substrate can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of the present invention based on a silicon carbide insulating substrate with double-sided aluminum coating.

[0030] Figure 2 The present invention is a schematic structural diagram of a silicon carbide power module prepared based on a silicon carbide insulating substrate with double-sided aluminum coating.

[0031] Figure 3 This is a reflow soldering simulation temperature curve diagram based on Comsol software of the present invention.

[0032] Figure 4 This is the stress distribution diagram of different substrates after heating in the present invention. Figure 3 a is Example 1, b is Comparative Example 1, c is Comparative Example 2, and d is Comparative Example 3.

[0033] Figure 5 The following are the simulation results of the warping of different substrates after being deformed by heat according to the present invention. Figure 4 a is Example 1, b is Comparative Example 1, c is Comparative Example 2, and d is Comparative Example 3.

[0034] Figure 6 It is a schematic structural diagram of the alumina insulating substrate of the present invention.

[0035] Figure 7 It is a schematic structural diagram of the aluminum nitride insulating substrate of the present invention.

[0036] Figure 8 It is a schematic structural diagram of the silicon nitride insulating substrate of the present invention.

[0037] Fig. 9 It is a schematic structural diagram of the aluminum-based insulating substrate of the present invention.

[0038] Illustration Description: 1. First silicon carbide layer, 2. Second silicon carbide layer, 3. Third silicon carbide layer, 4. First metal layer, 5. Second metal layer, 6. Upper copper layer, 7. Lower copper layer, 8. Solder layer, 9. Chip.

[0039] 1-1, aluminum oxide layer, 1-2, aluminum nitride layer, 1-3, silicon nitride layer, 1-4, aluminum layer. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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.

[0041] The invention is further described below through specific examples.

[0042] Example 1 A silicon carbide insulating substrate based on double-sided aluminum coating, such as Figure 1 As shown, including: Along the thickness direction of the silicon carbide insulating substrate, the silicon carbide insulating substrate is provided with a first silicon carbide layer 1, a second silicon carbide layer 2 and a third silicon carbide layer 3 from top to bottom, and the thickness of the first silicon carbide layer 1, the second silicon carbide layer 2 and the third silicon carbide layer 3 is 100μm; a first metal layer 4 is provided between the first silicon carbide layer 1 and the second silicon carbide layer 2, and a second metal layer 5 is provided between the second silicon carbide layer 2 and the third silicon carbide layer 3, and the first metal layer 4 and the second metal layer 5 are both aluminum metal layers, and the thickness of the aluminum metal layer is 50μm.

[0043] An upper copper layer 6 is provided on the first silicon carbide layer 1, and the upper copper layer 6 is provided with an etching position; a lower copper layer 7 is provided on the third silicon carbide layer 3; the thickness of the upper copper layer 6 and the lower copper layer 7 are both 300 μm.

[0044] A first titanium metal bonding layer is provided between the first silicon carbide layer and the upper copper layer, and a second titanium metal bonding layer is provided between the third silicon carbide layer and the lower copper layer. The thickness of the first titanium metal bonding layer and the second titanium metal bonding layer are both 50 nm.

[0045] A method for preparing a double-sided aluminum-coated silicon carbide insulating substrate comprises the following steps: S1. Using a sputtering method, metal aluminum is sputtered and deposited on the upper surface of the second silicon carbide layer 2 to metallize the silicon carbide surface with a thickness of 1 μm. Then, metal aluminum is deposited by electroplating to a thickness of 50 μm to obtain a first metal layer 4.

[0046] S2. Using a sputtering method, metal aluminum is sputtered and deposited on the lower surface of the second silicon carbide layer 2 to metallize the silicon carbide surface to a thickness of 1 μm. Then, metal aluminum is deposited by electroplating to a thickness of 50 μm to obtain a second metal layer 5.

[0047] S3. Use acetone to thoroughly clean the surface of the first metal layer 4 to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the metal aluminum layer to increase the contact surface area and enhance adhesion. Then place it in a chemical vapor deposition reaction chamber and deposit silicon carbide in a mixture of hydrogen and monosilane at 1000°C. Control the deposition rate to ensure that a thickness of 100μm is deposited without damaging the metal aluminum layer. After the deposition is completed, anneal it at 200°C for 8h in a nitrogen environment to obtain a first silicon carbide layer 1.

[0048] S4. Use acetone to thoroughly clean the aluminum surface of the second metal layer 5 to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the metal aluminum layer to increase the contact surface area and enhance adhesion. Then place it in a chemical vapor deposition reaction chamber and deposit silicon carbide in a mixture of hydrogen and monosilane at 1000°C. Control the deposition rate to ensure that a thickness of 100μm is deposited without damaging the metal aluminum layer. After the deposition is completed, anneal it at 200°C for 8h in a nitrogen environment to obtain a third silicon carbide layer 3.

[0049] S5. Clean the surface of the first silicon carbide layer 1, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the first silicon carbide layer 1 to increase the contact area, and after the above surface treatment, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 50μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer with a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current is evenly distributed to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300°C for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain an upper copper layer 6.

[0050] S6. Clean the surface of the third silicon carbide layer 3, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the third silicon carbide layer 3 to increase the contact area, and after the above surface treatment, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 50μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer with a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current is evenly distributed to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300°C for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain a lower copper layer 7.

[0051] S7, cleaning the surface of the upper copper layer 6, cleaning it with acetone to remove the surface organic matter, then ultrasonically cleaning the surface to remove microparticles, and drying it in a nitrogen environment; after drying, evenly coating a layer of photoresist on the copper surface, the thickness of the coating is 2μm, pre-drying the photoresist after coating to remove the solvent in the photoresist, using an ultraviolet light source to expose the photoresist through a mask, placing the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer, and wet etching using a chemical etching solution that can dissolve copper materials, i.e., wet etching using a sulfuric acid solution, this step requires controlling the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed; after the wet etching is completed, using acetone to remove the photoresist, leaving the etched upper copper layer 6, to obtain a silicon carbide insulating substrate based on double-sided aluminum coating.

[0052] Example 2 A silicon carbide insulating substrate based on double-sided aluminum coating, such as Figure 1 As shown, including: Along the thickness direction of the silicon carbide insulating substrate, the silicon carbide insulating substrate is provided with a first silicon carbide layer 1, a second silicon carbide layer 2 and a third silicon carbide layer 3 from top to bottom, and the thickness of the first silicon carbide layer 1, the second silicon carbide layer 2 and the third silicon carbide layer 3 are all 100μm; a first metal layer 4 is provided between the first silicon carbide layer 1 and the second silicon carbide layer 2, and a second metal layer 5 is provided between the second silicon carbide layer 2 and the third silicon carbide layer 3, and the first metal layer 4 and the second metal layer 5 are both aluminum metal layers, and the thickness of the aluminum metal layers is 50μm.

[0053] An upper copper layer 6 is provided on the first silicon carbide layer 1, and the upper copper layer 6 is provided with an etching position; a lower copper layer 7 is provided on the third silicon carbide layer 3; the thickness of the upper copper layer 6 and the lower copper layer 7 are both 300 μm.

[0054] A first titanium metal bonding layer is provided between the first silicon carbide layer and the upper copper layer, and a second titanium metal bonding layer is provided between the third silicon carbide layer and the lower copper layer. The thickness of the first titanium metal bonding layer and the second titanium metal bonding layer are both 100 nm.

[0055] A method for preparing a double-sided aluminum-coated silicon carbide insulating substrate comprises the following steps: S1. Using a sputtering method, metal aluminum is sputtered and deposited on the upper surface of the second silicon carbide layer 2 to metallize the silicon carbide surface with a thickness of 1 μm. Then, metal aluminum is deposited by electroplating to a thickness of 50 μm to obtain a first metal layer 4.

[0056] S2. Using a sputtering method, metal aluminum is sputtered and deposited on the lower surface of the second silicon carbide layer 2 to metallize the silicon carbide surface to a thickness of 1 μm. Then, metal aluminum is deposited by electroplating to a thickness of 50 μm to obtain a second metal layer 5.

[0057] S3. Use acetone to thoroughly clean the aluminum surface of the first metal layer 4 to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the metal aluminum layer to increase the contact surface area and enhance adhesion. Then place it in a chemical vapor deposition reaction chamber and deposit silicon carbide in a mixture of hydrogen and monosilane at 1000°C. Control the deposition rate to ensure that a thickness of 100μm is deposited without damaging the metal aluminum layer. After the deposition is completed, anneal it at 200°C for 8h in a nitrogen environment to obtain a first silicon carbide layer 1.

[0058] S4. Use acetone to thoroughly clean the aluminum surface of the second metal layer 5 to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the metal aluminum layer to increase the contact surface area and enhance adhesion. Then place it in a chemical vapor deposition reaction chamber and deposit silicon carbide in a mixture of hydrogen and monosilane at 1000°C. Control the deposition rate to ensure that a thickness of 100μm is deposited without damaging the metal aluminum layer. After the deposition is completed, anneal it at 200°C for 8h in a nitrogen environment to obtain a third silicon carbide layer 3.

[0059] S5. Clean the surface of the first silicon carbide layer 1, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that the surface is free of pollutants, use sandblasting technology to roughen the surface of the first silicon carbide layer 1 to increase the contact area, and after the above surface treatment, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 100μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer with a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300℃ for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain an upper copper layer 6.

[0060] S6. Clean the surface of the third silicon carbide layer 3, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that the surface is free of pollutants, use sandblasting technology to roughen the surface of the first silicon carbide layer 3 to increase the contact area, and after the above surface treatment, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 100μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer with a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300℃ for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain a lower copper layer 7.

[0061] S7, cleaning the surface of the upper copper layer 6, cleaning it with acetone to remove the surface organic matter, then ultrasonically cleaning the surface to remove microparticles, and drying it in a nitrogen environment; after drying, evenly coating a layer of photoresist on the copper surface, the thickness of the coating is 2μm, pre-drying the photoresist after coating to remove the solvent in the photoresist, using an ultraviolet light source to expose the photoresist through a mask, placing the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer, and wet etching, that is, using a chemical etching solution that can dissolve copper materials, such as a sulfuric acid solution, for wet etching. This step requires controlling the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed; after the wet etching is completed, using acetone to remove the photoresist, leaving the etched upper copper layer 6, to obtain a silicon carbide insulating substrate based on double-sided aluminum coating.

[0062] Example 3 A silicon carbide insulating substrate based on double-sided aluminum coating, such as Figure 1 As shown, including: Along the thickness direction of the silicon carbide insulating substrate, the silicon carbide insulating substrate is provided with a first silicon carbide layer 1, a second silicon carbide layer 2 and a third silicon carbide layer 3 from top to bottom, and the thickness of the first silicon carbide layer 1, the second silicon carbide layer 2 and the third silicon carbide layer 3 are all 100μm; a first metal layer 4 is provided between the first silicon carbide layer 1 and the second silicon carbide layer 2, and a second metal layer 5 is provided between the second silicon carbide layer 2 and the third silicon carbide layer 3, and the first metal layer 4 and the second metal layer 5 are both aluminum metal layers, and the thickness of the aluminum metal layers is 50μm.

[0063] An upper copper layer 6 is provided on the first silicon carbide layer 1, and the upper copper layer 6 is provided with an etching position; a lower copper layer 7 is provided on the third silicon carbide layer 3; the thickness of the upper copper layer 6 and the lower copper layer 7 are both 300 μm.

[0064] A first titanium metal bonding layer is provided between the first silicon carbide layer and the upper copper layer, and a second titanium metal bonding layer is provided between the third silicon carbide layer and the lower copper layer. The thickness of the first titanium metal bonding layer and the second titanium metal bonding layer are both 80 nm.

[0065] A method for preparing a double-sided aluminum-coated silicon carbide insulating substrate comprises the following steps: S1. Using a sputtering method, metal aluminum is sputtered and deposited on the upper surface of the second silicon carbide layer 2 to metallize the silicon carbide surface with a thickness of 1 μm. Then, metal aluminum is deposited by electroplating to a thickness of 50 μm to obtain a first metal layer 4.

[0066] S2. Using a sputtering method, metal aluminum is sputtered and deposited on the lower surface of the second silicon carbide layer 2 to metallize the silicon carbide surface to a thickness of 1 μm. Then, metal aluminum is deposited by electroplating to a thickness of 50 μm to obtain a second metal layer 5.

[0067] S3. Use acetone to thoroughly clean the aluminum surface of the first metal layer 4 to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the metal aluminum layer to increase the contact surface area and enhance adhesion. Then place it in a chemical vapor deposition reaction chamber and deposit silicon carbide in a mixture of hydrogen and monosilane at 1000°C. Control the deposition rate to ensure that a thickness of 100μm is deposited without damaging the metal aluminum layer. After the deposition is completed, anneal it at 200°C for 8h in a nitrogen environment to obtain a first silicon carbide layer 1.

[0068] S4. Use acetone to thoroughly clean the aluminum surface of the second metal layer 5 to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the metal aluminum layer to increase the contact surface area and enhance adhesion. Then place it in a chemical vapor deposition reaction chamber, and deposit silicon carbide at 1000°C in a mixture of hydrogen and monosilane. Control the deposition rate to ensure that the thickness of 100μm is deposited without damaging the metal aluminum layer; after the deposition is completed, anneal it at 200°C for 8h in a nitrogen environment to obtain a third silicon carbide layer 3.

[0069] S5. Clean the surface of the first silicon carbide layer 1, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the first silicon carbide layer 1 to increase the contact area, and after the above surface treatment, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 80μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer with a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300℃ for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain an upper copper layer 6.

[0070] S6. Clean the surface of the third silicon carbide layer 3, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the first silicon carbide layer 3 to increase the contact area, and after the above surface treatment, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 80μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer with a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300°C for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain a lower copper layer 7.

[0071] S7, cleaning the surface of the upper copper layer 6, cleaning it with acetone to remove the surface organic matter, then ultrasonically cleaning the surface to remove microparticles, and drying it in a nitrogen environment; after drying, evenly coating a layer of photoresist on the copper surface, the thickness of the coating is 2μm, pre-drying the photoresist after coating to remove the solvent in the photoresist, using an ultraviolet light source to expose the photoresist through a mask, placing the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer, and wet etching using a chemical etching solution that can dissolve copper materials, i.e., wet etching using a sulfuric acid solution, this step needs to control the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed, so as to obtain a silicon carbide insulating substrate based on double-sided aluminum coating.

[0072] Comparative Example 1 An alumina insulating substrate, such as Figure 6 As shown, including: Along the thickness direction of the aluminum nitride insulating substrate, the aluminum nitride insulating substrate is provided with a lower copper layer 7, an aluminum oxide layer 1-1 and an upper copper layer 6 from bottom to top, and the thickness of the aluminum oxide layer 1-1 is 300μm; the thickness of the upper copper layer 6 and the lower copper layer 7 are both 300μm, and the upper copper layer 6 is provided with an etching position.

[0073] A titanium metal bonding layer is provided between the lower copper layer 7 and the aluminum oxide layer 1-1, and between the upper copper layer 6 and the aluminum oxide layer 1-1, and the thickness of the bonding layer is 50 nm.

[0074] The method for preparing the above-mentioned alumina insulating substrate comprises the following steps: S1. Clean the upper surface of the aluminum oxide layer 1-1, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the aluminum oxide layer 1-1 to increase the contact area, and after the surface has been treated as above, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 50μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer, the sputtering thickness is 30μm, after the sputtering is completed, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer to a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after the electroplating is completed, annealing treatment is required in a nitrogen environment, and annealing is performed at 300℃ for 8h; after the annealing is completed, the copper surface is polished to eliminate surface unevenness and defects to obtain an upper copper layer 6.

[0075] S2. Clean the lower surface of the aluminum oxide layer 1-1, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the aluminum oxide layer 1-1 to increase the contact area, and after the surface is treated as above, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 50μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer, the sputtering thickness is 30μm, after sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer to a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, it is necessary to anneal in a nitrogen environment at 300℃ for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain a lower copper layer 7.

[0076] S3, cleaning the surface of the upper copper layer 6, cleaning it with acetone to remove the surface organic matter, then ultrasonically cleaning the surface to remove microparticles, and drying it in a nitrogen environment; after drying, evenly coating a layer of photoresist on the copper surface, the thickness of the coating is 2μm, pre-drying the photoresist after coating to remove the solvent in the photoresist, using an ultraviolet light source to expose the photoresist through a mask, placing the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer, and wet etching using a chemical etching solution that can dissolve copper materials, i.e., wet etching using a sulfuric acid solution, this step needs to control the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed, and an alumina insulating substrate can be obtained.

[0077] Comparative Example 2 An aluminum nitride insulating substrate, such as Figure 7 As shown, including: Along the thickness direction of the aluminum nitride insulating substrate, the aluminum nitride insulating substrate is provided with a lower copper layer 7, an aluminum nitride layer 1-2 and an upper copper layer 6 from top to bottom. The thickness of the aluminum nitride layer 1-2 is 300 μm, the thickness of the upper copper layer 6 and the lower copper layer 7 are both 300 μm, and the upper copper layer 6 is provided with an etching position.

[0078] A titanium metal bonding layer is provided between the lower copper layer 7 and the aluminum oxide layer 1-1, and between the upper copper layer 6 and the aluminum oxide layer 1-1, and the thickness of the bonding layer is 50 nm.

[0079] The method for preparing the aluminum nitride insulating substrate comprises the following steps: S5. Clean the aluminum nitride layer 1-2, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the aluminum nitride layer 1-2 to increase the contact area, and after the surface has been treated as above, use magnetron sputtering to deposit titanium metal under vacuum conditions, and the thickness of the titanium metal layer is 50μm as a bonding layer. Magnetron sputtering of copper metal with a sputtering thickness of 30μm is performed on the bonding layer. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer to a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300°C for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain an upper copper layer 6.

[0080] S6. Clean the aluminum nitride layer 1-2, use an organic solvent to remove impurities, use ultrasound to clean microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the aluminum nitride layer 1-2 to increase the contact area, and after the above surface treatment, use magnetron sputtering to deposit titanium metal under vacuum conditions. The thickness of the titanium metal layer is 50μm as a bonding layer. Magnetron sputtering copper metal is performed on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer to a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300℃ for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0081] S7, cleaning the surface of the upper copper layer 6, cleaning it with acetone to remove the surface organic matter, then ultrasonically cleaning the surface to remove microparticles, and drying it in a nitrogen environment; after drying, evenly coating a layer of photoresist on the copper surface, the thickness of the coating is 2μm, pre-drying the photoresist after coating to remove the solvent in the photoresist, using an ultraviolet light source to expose the photoresist through a mask, placing the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer, and wet etching using a chemical etching solution that can dissolve copper materials, that is, wet etching with a sulfuric acid solution, this step needs to control the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed; after the wet etching is completed, using acetone to remove the photoresist, leaving the etched upper copper layer 6, you can get an aluminum nitride insulating substrate.

[0082] Comparative Example 3 A silicon nitride insulating substrate, such as Figure 8 As shown, including: Along the thickness direction of the silicon nitride insulating substrate, the silicon nitride insulating substrate is provided with a lower copper layer 7, silicon nitride layers 1-3 and an upper copper layer 6 from bottom to top, and the thickness of the silicon nitride layer 1-3 is 300μm; the thickness of the upper copper layer 6 and the lower copper layer 7 are both 300μm, and the upper copper layer 6 is provided with an etching position.

[0083] A titanium metal bonding layer is provided between the lower copper layer 7 and the silicon nitride layer 1-3, and between the upper copper layer 6 and the silicon nitride layer 1-3, and the thickness of the bonding layer is 50 nm.

[0084] The method for preparing the silicon nitride insulating substrate comprises the following steps: S1. Clean the upper surface of the silicon nitride layer 1-3, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the silicon nitride layer 1-3 to increase the contact area, and after the surface is treated as above, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 5μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer with a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300°C for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain an upper copper layer 6.

[0085] S2. Clean the lower surface of the silicon nitride layer 1-3, use an organic solvent to remove impurities, use ultrasonic cleaning of microscopic particles to ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the silicon nitride layer 1-3 to increase the contact area, and after the surface is treated as above, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 50μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer, the sputtering thickness is 30μm, after sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer to a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment, annealing at 300℃ for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain a lower copper layer 7.

[0086] S3, cleaning the surface of the upper copper layer 6, cleaning it with acetone to remove the surface organic matter, then ultrasonically cleaning the surface to remove microparticles, and drying it in a nitrogen environment; after drying, evenly coating a layer of photoresist on the copper surface, the thickness of the coating is 2μm, pre-drying the photoresist after coating to remove the solvent in the photoresist, using an ultraviolet light source to expose the photoresist through a mask, placing the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer, and wet etching using a chemical etching solution that can dissolve copper materials, that is, wet etching with a sulfuric acid solution, this step needs to control the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed; after the wet etching is completed, using acetone to remove the photoresist, leaving the etched upper copper layer 6, and a silicon nitride insulating substrate can be obtained.

[0087] Comparative Example 4 An aluminum-based insulating substrate, such as Fig. 9 As shown, including: Along the thickness direction of the aluminum-based insulating substrate, the aluminum-based insulating substrate is provided with a lower copper layer 7, aluminum layers 1-4 and an upper copper layer 6 from bottom to top, and the thickness of the aluminum layer 1-4 is 300μm; the thickness of the upper copper layer 6 and the lower copper layer 7 are both 300μm, and the upper copper layer 6 is provided with an etching position.

[0088] A titanium metal bonding layer is provided between the lower copper layer 7 and the aluminum oxide layer 1-1, and between the upper copper layer 6 and the aluminum layer 1-4, and the thickness of the bonding layer is 50 nm.

[0089] The preparation method of the aluminum-based insulating substrate comprises the following steps: S1. Clean the aluminum layers 1-4, use organic solvents to remove impurities, use ultrasonic waves to clean microscopic particles, ensure that there are no pollutants on the surface, use sandblasting technology to roughen the surface of the aluminum layers 1-4 to increase the contact area, and after the above surface treatment, use magnetron sputtering to deposit titanium metal under vacuum conditions, the thickness of the titanium metal layer is 50μm, as a bonding layer, and magnetron sputter copper metal on the bonding layer with a sputtering thickness of 30μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer with a thickness of 300μm; during the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness; after electroplating, annealing treatment is required in a nitrogen environment at 300℃ for 8h; after annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain an upper copper layer 6.

[0090] S2, the aluminum layer is cleaned, organic solvents are used to remove impurities, microscopic particles are cleaned with ultrasound to ensure that there are no pollutants on the surface, and the surface of the aluminum layer 1-4 is roughened by sandblasting to increase the contact area. After the surface is treated above, titanium metal is deposited by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm, which is used as an adhesive layer. Copper metal is magnetron sputtered on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, the surface and adhesion of the copper layer are checked, and electroplating is performed on the sputtered copper layer with a thickness of 300 μm. During the electroplating process, it is necessary to ensure that the current distribution is uniform to avoid uneven coating thickness. After the electroplating is completed, annealing treatment is required in a nitrogen environment, and annealing is performed at 300 ° C for 8 hours. After annealing, the copper surface is polished to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0091] S3, cleaning the surface of the upper copper layer 6, cleaning it with acetone to remove the surface organic matter, then ultrasonically cleaning the surface to remove microparticles, and drying it in a nitrogen environment; after drying, evenly coating a layer of photoresist on the copper surface, the thickness of the coating is 2μm, pre-drying the photoresist after coating to remove the solvent in the photoresist, using an ultraviolet light source to expose the photoresist through a mask, placing the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer, and wet etching using a chemical etching solution that can dissolve copper materials, that is, wet etching using a sulfuric acid solution. This step requires controlling the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed, and an aluminum-based insulating substrate can be obtained.

[0092] The heat dissipation performance of the insulating substrates of Example 1 and Comparative Examples 1 to 4 was studied, and the results are shown in Table 1.

[0093] Table 1 Thermal conductivity of insulating substrates of Example 1 and Comparative Examples 1 to 4

[0094] As shown in Table 1, according to heat transfer theory, the material with greater thermal conductivity has better heat transfer under the same conditions. The thermal conductivity of silicon carbide used as the insulating layer in the present invention, that is, SiC as the insulating layer, is greater than that of the above three materials. Therefore, from a theoretical analysis, using silicon carbide as the ceramic layer can reduce the junction temperature of the chip and help the module dissipate heat.

[0095] The thermal expansion coefficients of the insulating substrates of Example 1 and Comparative Examples 1 to 4 were studied. The results are shown in Table 2.

[0096] Table 2 Thermal expansion coefficients of insulating substrates of Example 1 and Comparative Examples 1 to 4

[0097] As shown in Table 2, from a theoretical analysis, the chip is SiC-based, and the silicon carbide substrate in Example 1 of the present invention can match the thermal expansion coefficient of the chip. At the same time, aluminum is coated on both sides of the silicon carbide, which can effectively alleviate the thermal stress shock to avoid damage to the chip.

[0098] The silicon carbide insulating substrate of Example 1 of the present invention and the insulating substrates of Comparative Examples 1 to 4 are used to prepare a silicon carbide power module. Taking the silicon carbide insulating substrate of Example 1 as an example, the structure of the silicon carbide power module is as follows: Figure 2 As shown, a solder layer 8 is arranged on the upper copper layer 6, a chip 9 is arranged on the solder layer 8, the material of the chip 9 is silicon carbide, the thickness of the solder layer 8 is 80 μm, and the specific specifications of the silicon carbide power module prepared by the silicon carbide insulating substrate of Example 1 and the insulating substrates of Comparative Examples 1 to Comparative Examples 4 are shown in Table 3.

[0099] It should be noted that the solder layer is generally tin paste or solder sheet, which is selected according to needs. The purpose of the solder is to weld the chip and the upper copper layer together. The solder layer and chip of the present invention are selected as an example, and the purpose is the same solder layer and chip. Compared with the substrate based on aluminum oxide, aluminum nitride, and silicon nitride as the insulating layer, the solder layer and chip are not included. A vacuum reflow soldering process is used to reduce the oxidation of components that may occur during the welding process. Reflow soldering heats the paste-shaped soft solder pre-applied to the pad to melt and solidify it. The vacuum value atmospheric pressure can be reduced to below 5mbar and maintained for a certain period of time, thereby establishing a mechanical and electrical connection between the surface mounted components and the pad. A soft soldering method. Reflow soldering is generally divided into four working zones: heating zone, insulation zone, reflow zone, and cooling zone. In addition, in order to reduce the void rate of the welding layer, high-quality welding is performed between the chip and the substrate in a vacuum environment. Silicon carbide chips are used, and the material of the solder layer is Sn. 5 Pb 92.5 Ag 2.5 After the solder paste is printed on the steel screen, it is sent to the reflow oven for reflow. The highest reflow temperature is set to 310℃ and maintained for 120s to complete the reflow.

[0100] Table 3 Specifications of silicon carbide power modules prepared from insulating substrates of Example 1 and Comparative Examples 1 to 3

[0101] The silicon carbide insulating substrate of Example 1 and the insulating substrates of Comparative Examples 1 to 3 were used to prepare silicon carbide power modules. Reflow soldering simulation was performed to compare the stress and deformation of the insulating substrate after heating. Under the same simulation conditions, the maximum stress of the silicon carbide insulating substrate provided by the present invention after reflow was 1.79E8N / m 2 , Comparative Example 1: Aluminum oxide Al 2 O 3The maximum stress of the material as an insulating substrate is 9.41E8N / m 2 In comparative example 2, the maximum stress of aluminum nitride AlN material as the insulating substrate is 1.26E9N / m 2 Comparative Example 3: Silicon nitride Si 3 N 4 The maximum stress of the material as an insulating substrate is 1.41E9N / m 2 The maximum deformation of the silicon carbide insulating substrate provided by the present invention after reflow is 1.29μm, with Al 2 O 3 The maximum deformation of the material as an insulating substrate is 2.84μm, the maximum deformation of AlN material as an insulating substrate is 2.08μm, and the maximum deformation of Si 3 N 4 The maximum deformation of the material as an insulating substrate is 1.84μm.

[0102] Figure 3 This is a temperature curve diagram of the silicon carbide insulating substrate reflow simulation based on Comsol software in Example 1 of the present invention. Figure 3 As shown in the figure, the soldering process is to heat the solder first, and then cool it down to solidify it after reaching the melting point, completing the soldering between the substrate and the chip. That is, the reflow soldering temperature process simulated in the Comsol simulation is that the temperature first rises from room temperature to 240°C, at which time the solder has not melted, and then continues to rise to 340°C, at which time the solder melts, and then cools down.

[0103] Figure 4 It is a stress distribution diagram of the silicon carbide insulating substrate of Example 1 of the present invention and the insulating substrates of Comparative Examples 1 to 3 after being heated. Figure 4 a is Example 1, b is Comparative Example 1, c is Comparative Example 2, and d is Comparative Example 3. Figure 4 As shown, by comparison, it can be seen that the silicon carbide insulating substrate proposed by the present invention is subjected to the least force.

[0104] Figure 5 The comparison results of the deformation of the silicon carbide insulating substrate of Example 1 of the present invention and the insulating substrates of Comparative Examples 1 to 3 after reflow soldering are shown. Figure 5 a is Example 1, b is Comparative Example 1, c is Comparative Example 2, and d is Comparative Example 3. Figure 5 As shown, by comparison, it can be seen that the silicon carbide insulating substrate proposed by the present invention has the smallest deformation.

[0105] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0106] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A silicon carbide insulating substrate based on double-sided aluminum coating, characterized in that: include: Along the thickness direction of the silicon carbide insulating substrate, the silicon carbide insulating substrate is provided with a first silicon carbide layer (1), a second silicon carbide layer (2) and a third silicon carbide layer (3) in sequence from top to bottom, and the thickness of the first silicon carbide layer (1), the second silicon carbide layer (2) and the third silicon carbide layer (3) are all 80 μm to 120 μm; a first metal layer (4) is provided between the first silicon carbide layer (1) and the second silicon carbide layer (2), and a second metal layer (5) is provided between the second silicon carbide layer (2) and the third silicon carbide layer (3), and the thickness of the first metal layer (4) and the second metal layer (5) are all 40 μm to 60 μm; An upper copper layer (6) is provided on the first silicon carbide layer (1), wherein the upper copper layer (6) is provided with an etching position; a lower copper layer (7) is provided on the third silicon carbide layer (3); the thickness of the upper copper layer (6) and the lower copper layer (7) are both 240 μm to 360 μm.

2. The double-sided aluminum-coated silicon carbide insulating substrate according to claim 1, characterized in that: The first metal layer (4) and the second metal layer (5) are both aluminum metal layers.

3. The double-sided aluminum-coated silicon carbide insulating substrate according to claim 1, characterized in that: A first bonding layer is provided between the first silicon carbide layer (1) and the upper copper layer (6), and a second bonding layer is provided between the third silicon carbide layer (3) and the lower copper layer (7).

4. The double-sided aluminum-coated silicon carbide insulating substrate according to claim 3, characterized in that: The thickness of the first bonding layer and the second bonding layer are both 50nm-100nm, and both the first bonding layer and the second bonding layer are titanium metal layers.

5. A method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to any one of claims 1 to 4, characterized in that: The following steps are involved: Using a sputtering method, sputtering and depositing metal elements on the upper surface and the lower surface of the second silicon carbide layer (2), respectively, metallizing the upper surface or the lower surface of the second silicon carbide layer (2), and then using an electroplating deposition method to deposit the metal elements to a thickness of 40 μm to 60 μm, respectively obtaining a first metal layer (4) and a second metal layer (5); Using a sputtering method, silicon carbide is sputter-deposited on the upper surface of the first metal layer (4) and the lower surface of the second metal layer (5), respectively, and then silicon carbide is deposited to a thickness of 80 μm to 120 μm using a chemical vapor deposition method, thereby obtaining a first silicon carbide layer (1) and a third silicon carbide layer (3), respectively; Using a sputtering method, metallic copper is sputter-deposited on the upper surface of the first silicon carbide layer (1) and the lower surface of the third silicon carbide layer (3), respectively, and then metallic copper is deposited to a thickness of 240 μm to 360 μm using an electroplating deposition method, thereby obtaining an upper copper layer (6) and a lower copper layer (7), respectively; A photoresist is coated on the upper copper layer (6), and etching is performed to form an etching position, thereby obtaining a silicon carbide insulating substrate based on double-sided aluminum coating.

6. The method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to claim 5, characterized in that: The thickness of the surface metallization is 1 μm to 5 μm.

7. The method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to claim 5, characterized in that: The thickness of the sputtering deposited copper metal is 20 μm to 30 μm.

8. The method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to claim 5, characterized in that: The temperature of chemical vapor deposition is 1000° C. to 1200° C., and the reaction gas used in the chemical vapor deposition process is a mixture of hydrogen and monosilane.

9. The method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to claim 5, characterized in that: After chemical vapor deposition or electroplating deposition, annealing is performed at 150°C to 300°C for 8h to 12h under nitrogen or inert gas.

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