A silicon carbide insulating substrate based on double-sided aluminum cladding and a preparation method thereof

Abstract

The present invention belongs to the field of semiconductor technology, and particularly relates to a silicon carbide insulating substrate based on double-sided aluminum coating and a preparation method thereof. Along the thickness direction of the silicon carbide insulating substrate, the silicon carbide insulating substrate is sequentially provided with a first silicon carbide layer, a second silicon carbide layer, and a third silicon carbide layer from top to bottom; 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; an upper copper layer is provided on the first silicon carbide layer, and the upper copper layer is provided with an etching position; a lower copper layer is provided on the third silicon carbide layer. In the present invention, three silicon carbide layers are provided on the silicon carbide insulating substrate, and metal layers are provided between each silicon carbide layer. Using silicon carbide as an insulating layer can reduce the chip thermal stress and junction temperature; setting a metal layer on the surface of the silicon carbide insulating layer can reduce the thermal stress impact, prevent the chip from being damaged due to excessive thermal stress, and improve the reliability of the module.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductors, and particularly relates to a silicon carbide insulating substrate with double-sided aluminum cladding and a preparation method thereof. Background Art

[0002] In power electronics applications, in order to improve the current-carrying capacity of power modules, generally multiple chips are configured into a multi-chip packaged power module. As a multi-chip packaged power module, it not only needs to have excellent electrothermal performance, but also needs to have good thermomechanical reliability, and the thermomechanical reliability determines the service life of the power module. With the continuous reduction of the size of power devices and the improvement of power density, the packaging of power modules is 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 operating characteristics, new challenges have been brought to the packaging and heat dissipation of silicon carbide power modules.

[0003] Currently, the substrates used for power modules are mainly divided into resin substrates, ceramic substrates, and metal substrate substrates; among them, the resin substrate has a thermal conductivity of 1 W / (m·K), with poor heat dissipation, heat resistance, and reliability, and is usually used for control boards; the metal substrate substrate has a thermal conductivity of about 2 W / (m·K) to 6 W / (m·K), and is mainly used for power modules below the rated 600V / 50A system; the ceramic substrate has a thermal conductivity of 20 W / (m·K) to 170 W / (m·K), and is commonly used for high-power and high-current silicon carbide power modules.

[0004] The heat dissipation of the silicon carbide power module packaging is mainly conducted to the shell through the ceramic copper clad formed by copper cladding on the ceramic substrate and then dissipated. Since oxygen-free copper has a high thermal conductivity, the determining factor for the thermal conductivity of the ceramic copper clad is the performance of the ceramic substrate material. Due to the large thermal resistance existing in the pad layer and its welding layer of this type of ceramic substrate, the inherent difference in the coefficient of thermal expansion between the ceramic substrate and copper in the ceramic copper clad will cause a large stress at the copper-ceramic interface when the ceramic copper clad substrate undergoes thermal cycling, resulting in ceramic cracking or copper layer peeling, easily causing the silicon carbide chip to be damaged by excessive thermal stress, making the silicon carbide power module 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] To solve the above problems, the present invention provides a silicon carbide insulating substrate based on double-sided aluminum cladding and a preparation method thereof. The insulating substrate formed based on silicon carbide material 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 for the substrate is the same as that of the silicon carbide chip, with the same thermal expansion. Plating a metal layer on the surface of the silicon carbide insulating layer can reduce the thermal stress impact and prevent the silicon carbide chip from being damaged due to excessive thermal stress, thus improving 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 operate in a high-temperature environment, generally, the power rating of a silicon carbide power module will decrease when the temperature is higher than a certain value, that is, the output power will decrease by 30% when the temperature rises by 20°C. In actual applications, the normal operating environment temperature will change due to climate changes and system operating conditions. The module generally does not operate continuously for a long time under its specified maximum ambient temperature conditions. If the temperature control of the module is appropriate, in most operating cases, only the capacity of the module at the highest ambient temperature needs to be limited to maximize the power of the module.

[0008] However, high temperature is the main factor affecting the thermo-mechanical reliability of power modules. To improve the heat dissipation performance of the module, the reliability of ceramic copper-clad substrates at high temperatures becomes increasingly important. Among them, the ceramic copper-clad substrate directly bonds a ceramic insulating substrate between two layers of copper. These ceramic insulating substrates are usually selected according to application cases and their thermal, mechanical, and electrical insulation properties. Common ceramic insulating substrate materials include alumina, aluminum nitride, silicon nitride, etc. Alumina is the most economical choice. Although it has relatively high mechanical strength, its thermal conductivity is much weaker compared with other materials, and it is relatively less suitable for 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, effectively reducing problems such as delamination and solder fatigue, but its mechanical strength is not yet dominant in large 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 cladding, including:

[0010] Along the thickness direction of the silicon carbide insulating substrate, a first silicon carbide layer, a second silicon carbide layer, and a third silicon carbide layer are sequentially provided on the silicon carbide insulating substrate from top to bottom. The thicknesses of the first silicon carbide layer, the second silicon carbide layer, and the third silicon carbide layer are all 80 μm to 120 μm. 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. The thicknesses of the first metal layer and the second metal layer are both 40 μm to 60 μm.

[0011] An upper copper layer is provided on the first silicon carbide layer, and the upper copper layer is provided with an etching position. A lower copper layer is provided on the third silicon carbide layer. The thicknesses of the upper copper layer and the lower copper layer are both 240 μm to 360 μm.

[0012] The silicon carbide insulating substrate provided by the present invention is provided with three silicon carbide layers on the silicon carbide insulating substrate, and metal layers are provided between each silicon carbide layer. That is, the silicon carbide insulating substrate is obtained by alternately arranging the silicon carbide layers and the metal layers. 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 rise too much. And a metal layer is provided on the surface of the silicon carbide layer. By utilizing its soft texture and good thermal conductivity, the thermal stress impact can be reduced at the same time, and the silicon carbide chip can be prevented from being damaged due to excessive thermal stress, and the reliability of the silicon carbide rate module can be improved. The silicon carbide insulating substrate is obtained by alternately arranging the silicon carbide layer and the metal layer, and the thickness between the silicon carbide layer and the metal layer is controlled to regulate the thermal expansion coefficient matching 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 raising the working temperature of the silicon carbide power module.

[0013] In some embodiments, both the first metal layer and the second metal layer are aluminum metal layers. It should be noted that in the present invention, aluminum metal is used as the metal layer, and the thermal conductivity is 237 W / (m·K). Due to the inherent difference in thermal expansion coefficient between ceramics and copper, when the ceramic copper-clad substrate undergoes thermal cycling, large stresses will be generated at the copper-ceramic interface, resulting in ceramic cracking or copper layer peeling. In the present invention, the thermal conductivity coefficients of the silicon carbide layer and the copper layer are similar. By utilizing its soft texture and good thermal conductivity, the thermal stress impact can be reduced at the same time, the chip can be prevented from being damaged due to excessive thermal stress, the reliability of the module can be improved, and the price of aluminum metal is relatively low.

[0014] In some embodiments, a first bonding layer is provided between the first silicon carbide layer and the upper copper layer, and a second bonding layer is provided between the third silicon carbide layer and the lower copper layer. The thicknesses of the first bonding layer and the second bonding layer are both 50 nm to 100 nm, and both the first bonding layer and the second bonding layer are titanium metal layers. It should be noted that copper particles can be directly plated after sputtering the titanium metal layer, that is, the direct copper plating method, which can save process costs.

[0015] The silicon carbide insulating substrate provided by the present invention has the same material as the silicon carbide chip. The insulating layer is composed of three silicon carbide layers, and the thickness between the silicon carbide layer and the metal layer is controlled to regulate the thermal expansion coefficient matching between the silicon carbide layer and the metal layer, so as to shorten the thermal resistance from the power device to the packaging substrate, improve the heat dissipation efficiency of the packaging substrate, 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, increasing the operating temperature of the silicon carbide power module, while reducing the thermal stress impact, being able to withstand more thermal shock tests, preventing the silicon carbide chip from being damaged due to excessive thermal stress, and improving the reliability of the silicon carbide power module.

[0016] On the other hand, the present invention provides a preparation method of the above-mentioned silicon carbide insulating substrate based on double-sided aluminum cladding, including the following steps:

[0017] By means of sputtering, metal elements are respectively sputtered and deposited on the upper surface and the lower surface of the second silicon carbide layer to metallize the upper surface or the lower surface of the second silicon carbide layer, and then by means of electroplating deposition, metal elements are deposited to a thickness of 40 μm to 60 μm to obtain the first metal layer and the second metal layer respectively.

[0018] By means of sputtering, silicon carbide is respectively sputtered and deposited on the upper surface of the first metal layer and the lower surface of the second metal layer, and then by means of chemical vapor deposition, silicon carbide is deposited to a thickness of 80 μm to 120 μm to obtain the first silicon carbide layer and the third silicon carbide layer respectively.

[0019] 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. Acetone or isopropyl acetone is used to thoroughly clean the aluminum surface to remove dust and other contaminants. After cleaning the surface, sandblasting 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 cleaning, silicon carbide is first sputtered on the first metal layer and the second metal layer, and then high-quality silicon carbide is deposited by means of chemical vapor deposition to obtain the first silicon carbide layer or the third silicon carbide layer.

[0020] By means of sputtering, metallic copper is respectively sputtered and deposited on the upper surface of the first silicon carbide layer and the lower surface of the third silicon carbide layer, and then by means of electroplating deposition, metallic copper is deposited to a thickness of 240 μm to 360 μm to obtain the upper copper layer and the lower copper layer respectively.

[0021] It should be noted that the deposition of metallic copper adopts the direct copper plating method, namely the DPC process. The full English name of DPC is Direct Plating Copper. It mainly uses surface deposition processes such as evaporation and magnetron sputtering for the metallization of the substrate surface. First, titanium is sputtered under vacuum conditions, then copper particles, and finally electroplating is used to increase the thickness. Then, the circuit is fabricated by the ordinary PCB process, and finally the thickness of the circuit is increased by electroplating / electroless 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 ultrasonic cleaning is used to remove microscopic particles to ensure that the surface is free of contaminants. The sandblasting process is used to roughen the surface of the silicon carbide to increase the contact area. After the surface is treated as above, metallic copper is sputter-deposited.

[0022] A photoresist is coated on the copper layer, and etching is carried out to form an etching site, obtaining a silicon carbide insulating substrate based on double-sided aluminum-clad.

[0023] It should be noted that the present invention does not make specific limitations on the sputtering method, electroplating deposition, and chemical vapor deposition method. That is, it is prepared by the sputtering process, electroplating deposition, and chemical vapor deposition commonly used by those skilled in the art. The sputtering process can make the surface metal uniform and delicate and the thickness controllable. After the sputtering process is completed, the electroplating deposition method is adopted. Among them, the temperature of the chemical vapor deposition is 1000°C to 1200°C, and the reaction gases used in the chemical vapor deposition process are a mixture of hydrogen and silane.

[0024] It should be noted that etching is carried out on the surface of the copper layer. Before etching, surface cleaning is first carried out. Acetone or isopropyl acetone is used for cleaning to remove surface organic substances, and then ultrasonic cleaning is used to remove microparticles on the surface. Finally, drying is carried out in a nitrogen environment. After drying, a layer of photoresist is evenly coated on the copper surface, and 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 using an ultraviolet light source through a mask. After exposure, the 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 means using a chemical etching solution that can dissolve copper materials, such as sulfuric acid solution, for wet etching. In this step, the etching time needs to be controlled to ensure that only the copper layer not covered by the photoresist is removed; dry etching means using plasma for dry etching, and the copper layer is selectively removed through a reaction gas such as chlorine gas. After wet etching is completed, acetone is used to remove the photoresist, leaving the etched copper layer. Finally, ultrasonic cleaning is carried out to obtain a complete silicon carbide insulating substrate.

[0025] 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 a controllable thickness and a uniform and fine surface metal on the upper and lower surfaces of the second silicon carbide layer, increasing the adhesion of the metal copper layer and the controllability of the thickness.

[0026] In some embodiments, the thickness of the sputter-deposited metal copper is 20 μm to 30 μm. It should be noted that after sputtering, the surface and adhesion of the copper layer are inspected, and electroplating is performed on the sputter-deposited copper layer until the thickness reaches 300 μm. During the electroplating process, it is necessary to ensure uniform current distribution to avoid uneven coating thickness.

[0027] In some embodiments, the temperature of chemical vapor deposition is 1000 °C to 1200 °C, and the reaction gases used in the chemical vapor deposition process are a mixture of hydrogen and silane. The deposition rate is controlled by chemical vapor deposition to ensure a deposition thickness of 100 μm without damaging the metal layer. After deposition, annealing is performed, and heat treatment is carried out in a nitrogen environment to enhance the bonding strength between materials.

[0028] In some embodiments, after chemical vapor deposition or electroplating deposition, annealing is performed at 150 °C to 300 °C for 8 h to 12 h under nitrogen or an inert gas. After electroplating, annealing treatment needs to be carried out in a nitrogen environment at a temperature of 150 °C to 300 °C for 8 h to 12 h to enhance the bonding strength between materials. After annealing, the surface is polished to eliminate surface unevenness and defects.

[0029] The present invention has the following beneficial effects compared with the prior art:

[0030] (4) The silicon carbide insulating substrate provided by the present invention 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 along the thickness direction of the silicon carbide insulating substrate; 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. That is, three silicon carbide layers are provided on the silicon carbide insulating substrate, and metal layers are provided between each silicon carbide layer. Using silicon carbide as an insulating layer can 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 provided on the surface of the silicon carbide insulating layer takes advantage of its soft texture and good thermal conductivity, and can reduce the thermal stress impact at the same time, preventing the silicon carbide chip from being damaged due to excessive thermal stress, and improving the reliability of the rate module; the present invention obtains the silicon carbide insulating substrate by alternately arranging the silicon carbide layer and the metal layer, controls the thickness between the silicon carbide layer and the metal layer, and regulates the thermal expansion coefficient matching 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.

[0031] (2) The preparation method of the silicon carbide insulating substrate provided by the present invention sputters and deposits metal elements on the upper surface or the lower surface of the second silicon carbide layer in a sputtering manner to form a first metal layer or a second metal layer, deposits a first silicon carbide layer or a third silicon carbide layer on the first metal layer or the second metal layer, and then sputters and deposits copper, and performs etching to form an etching position, obtaining a silicon carbide insulating substrate based on double-sided aluminum coating, the surface metal of which is uniform, delicate, and thickness-controllable, with good adhesion performance, and can improve the reliability of the insulating substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of the silicon carbide insulating substrate based on double-sided aluminum coating of the present invention.

[0033] Figure 2 It is a schematic structural diagram of preparing a silicon carbide power module with the silicon carbide insulating substrate based on double-sided aluminum coating of the present invention.

[0034] Figure 3 It is a temperature curve diagram of reflow soldering simulation based on Comsol software of the present invention.

[0035] Figure 4 It is a stress distribution diagram of different substrates after being heated in the present invention. Figure 3 In which, a is Example 1, b is Comparative Example 1, c is Comparative Example 2, and d is Comparative Example 3.

[0036] Figure 5This is the warping simulation result diagram of different substrates of the present invention after being heated and deformed. Figure 4 In [0000088], a is Example 1, b is Comparative Example 1, c is Comparative Example 2, and d is Comparative Example 3.

[0037] Figure 6 This is the structural schematic diagram of the alumina insulating substrate of the present invention.

[0038] Figure 7 This is the structural schematic diagram of the aluminum nitride insulating substrate of the present invention.

[0039] Figure 8 This is the structural schematic diagram of the silicon nitride insulating substrate of the present invention.

[0040] Figure 9 This is the structural schematic diagram of the aluminum-based insulating substrate of the present invention.

[0041] Illustration:

[0042] 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.

[0043] 1-1. Alumina layer, 1-2. Aluminum nitride layer, 1-3. Silicon nitride layer, 1-4. Aluminum layer. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0045] The following is further illustrated by specific embodiments.

[0046] Example 1

[0047] A silicon carbide insulating substrate based on double-sided aluminum cladding, as Figure 1 shown, includes:

[0048] Along the thickness direction of the silicon carbide insulating substrate, the silicon carbide insulating substrate is successively 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. The thicknesses of the first silicon carbide layer 1, the second silicon carbide layer 2, and the third silicon carbide layer 3 are all 100 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. 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 50 μm.

[0049] 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 thicknesses of both the upper copper layer 6 and the lower copper layer 7 are 300 μm.

[0050] 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 thicknesses of both the first titanium metal bonding layer and the second titanium metal bonding layer are 50 nm.

[0051] A preparation method of a silicon carbide insulating substrate with aluminum cladding on both sides includes the following steps:

[0052] S1. By means of sputtering, deposit metal aluminum on the upper surface of the second silicon carbide layer 2 for silicon carbide surface metallization with a thickness of 1 μm, and then deposit metal aluminum to a thickness of 50 μm by means of electroplating deposition to obtain a first metal layer 4.

[0053] S2. By means of sputtering, deposit metal aluminum on the lower surface of the second silicon carbide layer 2 for silicon carbide surface metallization with a thickness of 1 μm, and then deposit metal aluminum to a thickness of 50 μm by means of electroplating deposition to obtain a second metal layer 5.

[0054] S3. Thoroughly clean the surface of the first metal layer 4 with acetone 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 the adhesion. Then place it in the reaction chamber of chemical vapor deposition, and deposit silicon carbide at a temperature of 1000 °C in a mixture of hydrogen and silane. Control the deposition rate to deposit a thickness of 100 μm on the premise of not damaging the metal aluminum layer; after deposition, perform annealing at 200 °C for 8 h in a nitrogen environment to obtain the first silicon carbide layer 1.

[0055] S4. Thoroughly clean the aluminum surface of the second metal layer 5 with acetone 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 the adhesion. Then place it in the reaction chamber of chemical vapor deposition, and deposit silicon carbide at a temperature of 1000 °C in a mixture of hydrogen and silane. Control the deposition rate to deposit a thickness of 100 μm on the premise of not damaging the metal aluminum layer; after deposition, perform annealing at 200 °C for 8 h in a nitrogen environment to obtain the third silicon carbide layer 3.

[0056] S5. Clean the surface of the first silicon carbide layer 1. Use organic solvents to remove impurities and ultrasonic cleaning to remove microscopic particles to ensure that the surface is free of contaminants. Use a sandblasting process to roughen the surface of the first silicon carbide layer 1 to increase the contact area. After the surface has been treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputter-deposited copper layer until the thickness reaches 300 μm. During the electroplating process, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment is required in a nitrogen environment at a temperature of 300 °C for 8 h. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the upper copper layer 6.

[0057] S6. Clean the surface of the third silicon carbide layer 3. Use organic solvents to remove impurities and ultrasonic cleaning to remove microscopic particles to ensure that the surface is free of contaminants. Use a sandblasting process to roughen the surface of the third silicon carbide layer 3 to increase the contact area. After the surface has been treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputter-deposited copper layer until the thickness reaches 300 μm. During the electroplating process, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment is required in a nitrogen environment at a temperature of 300 °C for 8 h. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0058] S7. Clean the surface of the upper copper layer 6. Clean it with acetone to remove surface organic matter and then use ultrasonic cleaning on the surface to remove fine particles, and dry it in a nitrogen environment. After drying, evenly coat a layer of photoresist on the copper surface with a coating thickness of 2 μm. After coating, pre-dry the photoresist to remove the solvent in the photoresist. Use an ultraviolet light source to expose the photoresist through a mask. Place the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer. Use wet etching, that is, use a chemical etching solution of sulfuric acid that can dissolve copper materials 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 wet etching, use acetone to remove the photoresist, leaving the etched upper copper layer 6, that is, a silicon carbide insulating substrate with double-sided aluminum cladding is obtained.

[0059] Example 2

[0060] A silicon carbide insulating substrate with double-sided aluminum cladding, as Figure 1 shown, includes:

[0061] Along the thickness direction of the silicon carbide insulating substrate, a first silicon carbide layer 1, a second silicon carbide layer 2, and a third silicon carbide layer 3 are sequentially provided on the silicon carbide insulating substrate from top to bottom. The thicknesses of the first silicon carbide layer 1, the second silicon carbide layer 2, and the third silicon carbide layer 3 are all 100 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. The first metal layer 4 and the second metal layer 5 are both aluminum metal layers, and the thicknesses of the aluminum metal layers are both 50 μm.

[0062] 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 thicknesses of the upper copper layer 6 and the lower copper layer 7 are both 300 μm.

[0063] 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 thicknesses of the first titanium metal bonding layer and the second titanium metal bonding layer are both 100 nm.

[0064] A preparation method of a silicon carbide insulating substrate with aluminum on both sides includes the following steps:

[0065] S1. By means of sputtering, deposit metallic aluminum on the upper surface of the second silicon carbide layer 2 to conduct surface metallization of silicon carbide with a thickness of 1 μm, and then deposit metallic aluminum by electroplating to a thickness of 50 μm to obtain the first metal layer 4.

[0066] S2. By means of sputtering, deposit metallic aluminum on the lower surface of the second silicon carbide layer 2 to conduct surface metallization of silicon carbide with a thickness of 1 μm, and then deposit metallic aluminum by electroplating to a thickness of 50 μm to obtain the second metal layer 5.

[0067] S3. Thoroughly clean the surface of the first metal layer 4 with acetone to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the aluminum metal layer to improve the contact surface area and enhance the adhesion. Then place it in the reaction chamber of chemical vapor deposition, and deposit silicon carbide at 1000 °C with a mixture of hydrogen and silane, control the deposition rate, and deposit a thickness of 100 μm on the premise of ensuring that the aluminum metal layer is not damaged. After the deposition is completed, anneal at 200 °C for 8 h in a nitrogen environment to obtain the first silicon carbide layer 1.

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

[0069] S5. Clean the surface of the first silicon carbide layer 1, use organic solvents to remove impurities, and use ultrasonic cleaning to remove microscopic particles to ensure the surface is free of contaminants. Use the sandblasting process to roughen the surface of the first silicon carbide layer 1 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 100 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During electroplating, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment is required in a nitrogen environment at 300 °C for 8 h. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the upper copper layer 6.

[0070] S6. Clean the surface of the third silicon carbide layer 3, use organic solvents to remove impurities, and use ultrasonic cleaning to remove microscopic particles to ensure the surface is free of contaminants. Use the sandblasting process to roughen the surface of the first silicon carbide layer 3 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 100 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During electroplating, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment is required in a nitrogen environment at 300 °C for 8 h. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0071] S7. Clean the surface of the upper copper layer 6 with acetone to remove surface organic matter, and then use ultrasonic cleaning to remove fine particles on the surface, and dry it in a nitrogen environment; after drying, evenly coat a layer of photoresist on the copper surface, with the thickness of the coating being 2 μm. After coating, pre-dry the photoresist to remove the solvent in the photoresist. Use an ultraviolet light source to expose the photoresist through a mask. Put the exposed substrate into a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer. Use wet etching, that is, use a chemical etching solution, sulfuric acid solution, which can dissolve copper materials, for wet etching. In this step, it is necessary to control the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed; after wet etching is completed, use acetone to remove the photoresist, leaving the etched upper copper layer 6, and a silicon carbide insulating substrate based on double-sided aluminum-clad can be obtained.

[0072] Example 3

[0073] A silicon carbide insulating substrate based on double-sided aluminum-clad, as Figure 1 shown, includes:

[0074] Along the thickness direction of the silicon carbide insulating substrate, the silicon carbide insulating substrate is sequentially 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. The thicknesses of the first silicon carbide layer 1, the second silicon carbide layer 2, and the third silicon carbide layer 3 are all 100 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. The first metal layer 4 and the second metal layer 5 are both aluminum metal layers, and the thicknesses of the aluminum metal layers are all 50 μm.

[0075] 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 thicknesses of the upper copper layer 6 and the lower copper layer 7 are both 300 μm.

[0076] 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 thicknesses of the first titanium metal bonding layer and the second titanium metal bonding layer are both 80 nm.

[0077] A preparation method for a silicon carbide insulating substrate based on double-sided aluminum-clad includes the following steps:

[0078] S1. Adopt sputtering to sputter-deposit metal aluminum on the upper surface of the second silicon carbide layer 2 for silicon carbide surface metallization, with a thickness of 1 μm, and then adopt electroplating deposition to deposit metal aluminum to a thickness of 50 μm to obtain the first metal layer 4.

[0079] S2. By means of sputtering, deposit metallic aluminum on the lower surface of the second silicon carbide layer 2 for metallization of the silicon carbide surface with a thickness of 1 μm, and then deposit metallic aluminum by electroplating to a thickness of 50 μm to obtain the second metal layer 5.

[0080] S3. Thoroughly clean the surface of the first metal layer 4 with acetone to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the metallic aluminum layer to increase the contact surface area and enhance the adhesion. Then place it in the reaction chamber of chemical vapor deposition and deposit silicon carbide at 1000 °C in a mixture of hydrogen and silane, controlling the deposition rate to deposit a thickness of 100 μm on the premise of not damaging the metallic aluminum layer; after deposition, perform annealing at 200 °C for 8 h in a nitrogen environment to obtain the first silicon carbide layer 1.

[0081] S4. Thoroughly clean the surface of the second metal layer 5 with acetone to remove dust and other contaminants. After cleaning the surface, use sandblasting to increase the roughness of the metallic aluminum layer to increase the contact surface area and enhance the adhesion. Then place it in the reaction chamber of chemical vapor deposition and deposit silicon carbide at 1000 °C in a mixture of hydrogen and silane, controlling the deposition rate to deposit a thickness of 100 μm on the premise of not damaging the metallic aluminum layer; after deposition, perform annealing at 200 °C for 8 h in a nitrogen environment to obtain the third silicon carbide layer 3.

[0082] S5. Clean the surface of the first silicon carbide layer 1, use organic solvents to remove impurities and use ultrasonic waves to clean microscopic particles to ensure that the surface has no contaminants. Use the sandblasting process to roughen the surface of the first silicon carbide layer 1 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions, and the thickness of the titanium metal layer is 80 μm as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer, and electroplate on the sputtered copper layer to a thickness of 300 μm; during electroplating, it is necessary to ensure uniform current distribution to avoid uneven coating thickness; after electroplating, annealing treatment needs to be carried out in a nitrogen environment, annealing at 300 °C for 8 h; after annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the upper copper layer 6.

[0083] S6. Clean the surface of the third silicon carbide layer 3. Use organic solvents to remove impurities and ultrasonic waves to clean microscopic particles to ensure that the surface is free of contaminants. Use a sandblasting process to roughen the surface of the first silicon carbide layer 3 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 80 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer, with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During electroplating, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment should be carried out in a nitrogen environment at a temperature of 300 °C for 8 hours. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0084] S7. Clean the surface of the upper copper layer 6. Clean it with acetone to remove surface organic substances, and then use ultrasonic waves to clean the surface to remove fine particles, and dry it in a nitrogen environment. After drying, evenly coat a layer of photoresist on the copper surface, with a coating thickness of 2 μm. After coating, pre-dry the photoresist to remove the solvent in the photoresist. Use an ultraviolet light source to expose the photoresist through a mask. Put the exposed substrate into a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer. Adopt wet etching, that is, use a chemical etching solution, sulfuric acid solution, which can dissolve copper materials, for wet etching. In this step, it is necessary to control the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed, and a silicon carbide insulating substrate based on double-sided aluminum-clad can be obtained.

[0085] Comparative Example 1

[0086] An alumina insulating substrate, as Figure 6 shown, includes:

[0087] Along the thickness direction of the aluminum nitride insulating substrate, the aluminum nitride insulating substrate is successively provided with a lower copper layer 7, an alumina layer 1-1, and an upper copper layer 6 from bottom to top. The thickness of the alumina layer 1-1 is 300 μm; the thicknesses of both the upper copper layer 6 and the lower copper layer 7 are 300 μm, and the upper copper layer 6 is provided with an etching position.

[0088] Titanium metal adhesive layers are provided between the lower copper layer 7 and the alumina layer 1-1, and between the upper copper layer 6 and the alumina layer 1-1. The thickness of the adhesive layer is 50 nm.

[0089] The preparation method of the above alumina insulating substrate includes the following steps:

[0090] S1. Clean the upper surface of the alumina layer 1-1. Use organic solvents to remove impurities and ultrasonic cleaning to remove microscopic particles to ensure that the surface is free of contaminants. Use a sandblasting process to roughen the surface of the alumina layer 1-1 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During the electroplating process, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment is required in a nitrogen environment at a temperature of 300 °C for 8 h. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the upper copper layer 6.

[0091] S2. Clean the lower surface of the alumina layer 1-1. Use organic solvents to remove impurities and ultrasonic cleaning to remove microscopic particles to ensure that the surface is free of contaminants. Use a sandblasting process to roughen the surface of the alumina layer 1-1 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During the electroplating process, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment is required in a nitrogen environment at a temperature of 300 °C for 8 h. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0092] S3. Clean the surface of the upper copper layer 6. Clean it with acetone to remove surface organic matter and then use ultrasonic cleaning on the surface to remove fine particles, and dry it in a nitrogen environment. After drying, evenly coat a layer of photoresist on the copper surface with a coating thickness of 2 μm. After coating, pre-dry the photoresist to remove the solvent in the photoresist. Use an ultraviolet light source to expose the photoresist through a mask. Place the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer. Use wet etching, that is, use a chemical etching solution, sulfuric acid solution, which can dissolve copper materials, 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, and the alumina insulating substrate can be obtained.

[0093] Comparative Example 2

[0094] An aluminum nitride insulating substrate, as Figure 7 shown, includes:

[0095] Along the thickness direction of the aluminum nitride insulating substrate, a lower copper layer 7, an aluminum nitride layer 1-2, and an upper copper layer 6 are sequentially provided from top to bottom. The thickness of the aluminum nitride layer 1-2 is 300 μm, and the thicknesses of both the upper copper layer 6 and the lower copper layer 7 are 300 μm. The upper copper layer 6 is provided with an etching position.

[0096] Titanium metal bonding layers are provided between the lower copper layer 7 and the alumina layer 1-1, and between the upper copper layer 6 and the alumina layer 1-1. The thickness of the bonding layer is 50 nm.

[0097] The preparation method of the above-mentioned aluminum nitride insulating substrate includes the following steps:

[0098] S5. Clean the aluminum nitride layer 1-2, remove impurities using organic solvents, clean microscopic particles with ultrasonic waves to ensure that the surface is free of contaminants. Use the sandblasting process to roughen the surface of the aluminum nitride layer 1-2 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as the bonding layer. Magnetron sputter copper metal on the bonding layer, with a sputtering thickness of 30 μm. After sputtering is completed, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During the electroplating process, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating is completed, annealing treatment needs to be carried out in a nitrogen environment, annealing at 300 °C for 8 h. After annealing is completed, polish the copper surface to eliminate surface unevenness and defects to obtain the upper copper layer 6.

[0099] S6. Clean the aluminum nitride layer 1-2, remove impurities using organic solvents, clean microscopic particles with ultrasonic waves to ensure that the surface is free of contaminants. Use the sandblasting process to roughen the surface of the aluminum nitride layer 1-2 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as the bonding layer. Magnetron sputter copper metal on the bonding layer, with a sputtering thickness of 30 μm. After sputtering is completed, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During the electroplating process, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating is completed, annealing treatment needs to be carried out in a nitrogen environment, annealing at 300 °C for 8 h. After annealing is completed, polish the copper surface to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0100] S7. Clean the upper copper layer 6. First, clean it with acetone to remove surface organic substances, and then use ultrasonic cleaning to remove micro-particles on the surface. Dry it in a nitrogen environment. After drying, evenly coat a layer of photoresist on the copper surface, with the thickness of the coating being 2 μm. After coating, pre-dry the photoresist to remove the solvent in the photoresist. Use an ultraviolet light source to expose the photoresist through a mask. Put the exposed substrate into a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer. Perform wet etching, that is, use a chemical etching solution, sulfuric acid solution, which can dissolve copper materials, for wet etching. In this step, it is necessary to control the etching time to ensure that only the upper copper layer 6 not covered by the photoresist is removed. After wet etching is completed, use acetone to remove the photoresist, leaving the etched upper copper layer 6, and then an aluminum nitride insulating substrate can be obtained.

[0101] Comparative Example 3

[0102] A silicon nitride insulating substrate, as Figure 8 shown, includes:

[0103] Along the thickness direction of the silicon nitride insulating substrate, the silicon nitride insulating substrate is successively provided with a lower copper layer 7, a silicon nitride layer 1-3, and an upper copper layer 6 from bottom to top. The thickness of the silicon nitride layer 1-3 is 300 μm; the thicknesses of both the upper copper layer 6 and the lower copper layer 7 are 300 μm, and the upper copper layer 6 is provided with an etching position.

[0104] There are titanium metal bonding layers 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. The thickness of the bonding layer is 50 nm.

[0105] The preparation method of the above-mentioned silicon nitride insulating substrate includes the following steps:

[0106] S1. Clean the upper surface of the silicon nitride layer 1-3. Use an organic solvent to remove impurities and ultrasonic cleaning to remove microscopic particles to ensure that the surface has no contaminants. Use a sandblasting process to roughen the surface of the silicon nitride layer 1-3 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 5 μm as an adhesive layer. Magnetron sputter copper metal on the adhesive layer, with the sputtering thickness being 30 μm. After sputtering is completed, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During the electroplating process, it is necessary to ensure uniform current distribution to avoid the phenomenon of uneven coating thickness. After electroplating is completed, annealing treatment needs to be carried out in a nitrogen environment, annealing at 300 °C for 8 h. After annealing is completed, polish the copper surface to eliminate surface unevenness and defects to obtain the upper copper layer 6.

[0107] S2. Clean the lower surface of the silicon nitride layer 1-3. Use organic solvents to remove impurities and ultrasonic waves to clean microscopic particles to ensure that the surface is free of contaminants. Use the sandblasting process to roughen the surface of the silicon nitride layer 1-3 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputtered copper layer until the thickness reaches 300 μm. During electroplating, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, perform annealing treatment in a nitrogen environment at 300 °C for 8 hours. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0108] S3. Clean the surface of the upper copper layer 6. Clean it with acetone to remove surface organic matter and then use ultrasonic waves to clean the surface to remove fine particles, and dry it in a nitrogen environment. After drying, evenly coat a layer of photoresist on the copper surface with a coating thickness of 2 μm. After coating, pre-dry the photoresist to remove the solvent in the photoresist. Use an ultraviolet light source to expose the photoresist through a mask. Place the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer. Perform wet etching, that is, use a chemical etching solution, sulfuric acid solution, which can dissolve copper materials, 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 wet etching, use acetone to remove the photoresist, leaving the etched upper copper layer 6, and then the silicon nitride insulating substrate can be obtained.

[0109] Comparative Example 4

[0110] An aluminum-based insulating substrate, as Figure 9 shown, includes:

[0111] Along the thickness direction of the aluminum-based insulating substrate, the aluminum-based insulating substrate is sequentially provided with a lower copper layer 7, an aluminum layer 1-4, and an upper copper layer 6 from bottom to top. The thickness of the aluminum layer 1-4 is 300 μm; the thicknesses 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.

[0112] Titanium metal adhesive layers are 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. The thickness of the adhesive layer is 50 nm.

[0113] Based on the preparation method of the aluminum-based insulating substrate, it includes the following steps:

[0114] S1. Clean the aluminum layers 1-4. Use organic solvents to remove impurities and ultrasonic cleaning to remove microscopic particles to ensure that the surface is free of contaminants. Use a sandblasting process to roughen the surfaces of the aluminum layers 1-4 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputter-deposited copper layer until the thickness reaches 300 μm. During electroplating, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment should be carried out in a nitrogen environment at a temperature of 300 °C for 8 h. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the upper copper layer 6.

[0115] S2. Clean the aluminum layer. Use organic solvents to remove impurities and ultrasonic cleaning to remove microscopic particles to ensure that the surface is free of contaminants. Use a sandblasting process to roughen the surfaces of the aluminum layers 1-4 to increase the contact area. After the surface is treated as above, deposit titanium metal by magnetron sputtering under vacuum conditions. The thickness of the titanium metal layer is 50 μm to serve as an adhesive layer. Magnetron sputter copper metal on the adhesive layer with a sputtering thickness of 30 μm. After sputtering, check the surface and adhesion of the copper layer. Electroplate on the sputter-deposited copper layer until the thickness reaches 300 μm. During electroplating, it is necessary to ensure uniform current distribution to avoid uneven coating thickness. After electroplating, annealing treatment should be carried out in a nitrogen environment at a temperature of 300 °C for 8 h. After annealing, polish the copper surface to eliminate surface unevenness and defects to obtain the lower copper layer 7.

[0116] S3. Conduct surface cleaning on the upper copper layer 6. Clean it with acetone to remove surface organic substances, and then use ultrasonic cleaning on the surface to remove fine particles, and dry it in a nitrogen environment. After drying, evenly coat a layer of photoresist on the copper surface with a coating thickness of 2 μm. After coating, pre-dry the photoresist to remove the solvent in the photoresist. Use an ultraviolet light source to expose the photoresist through a mask. Place the exposed substrate in a developer to dissolve the unexposed photoresist, leaving a patterned photoresist layer. Adopt wet etching, that is, use a chemical etching solution, sulfuric acid solution, which can dissolve copper materials, 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, and then the aluminum-based insulating substrate can be obtained.

[0117] Study the heat dissipation performance of the insulating substrates in Example 1 and Comparative Examples 1-4. The results are shown in Table 1.

[0118] Table 1 Thermal conductivities of the insulating substrates in Example 1 and Comparative Examples 1-4

[0119]

[0120] As described in Table 1, according to the heat transfer theory, under the same conditions, the material with a higher thermal conductivity transfers heat better. The silicon carbide used in the present invention as the insulating layer, that is, SiC as the insulating layer, has a thermal conductivity greater than that of the above three materials. Therefore, from theoretical analysis, using silicon carbide as the ceramic layer can reduce the chip junction temperature and contribute to the heat dissipation of the module.

[0121] The thermal expansion coefficients of the insulating substrates of Example 1 and Comparative Examples 1 to 4 were studied, and the results are shown in Table 2.

[0122] Table 2 Thermal expansion coefficients of the insulating substrates of Example 1 and Comparative Examples 1 to 4

[0123]

[0124] As shown in Table 2, from theoretical analysis, the chip is SiC-based, and the silicon carbide substrate of 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 well relieve the thermal stress impact so as not to damage the chip.

[0125] The silicon carbide power modules were prepared using the silicon carbide insulating substrate of Example 1 of the present invention and the insulating substrates of Comparative Examples 1 to 4. Taking the silicon carbide power module prepared with the silicon carbide insulating substrate of Example 1 as an example, the structure of the silicon carbide power module is as Figure 2 shown. A solder layer 8 is provided on the upper copper layer 6, a chip 9 is provided 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 modules prepared with the silicon carbide insulating substrate of Example 1 and the insulating substrates of Comparative Examples 1 to 4 are shown in Table 3.

[0126] It should be noted that the solder layer is generally solder paste or solder sheet, which is selected according to requirements. The purpose of the solder is to weld the chip and the upper copper layer. In this example, the solder layer and the chip are selected as an example, and the purpose is the same for the solder layer and the chip. Compared with the insulating layer substrates based on alumina, aluminum nitride, and silicon nitride, the solder layer and the chip are not included. The vacuum reflow soldering process is used to reduce the oxidation that may occur during the welding process. The reflow soldering heats the pre-applied paste-shaped soft solder on the pads to make it melt and solidify. The vacuum value can be reduced to below 5 mbar of atmospheric pressure and maintained for a certain period of time, so as to establish a mechanical and electrical connection between the surface-mounted components and the pads, which is a soft soldering method. The reflow soldering generally includes four working zones: heating zone, holding zone, reflow zone, and cooling zone. In addition, to reduce the void ratio of the welding layer, high-quality welding is carried out between the chip and the substrate in a vacuum environment. Silicon carbide chips are used, and the material of the solder layer is Sn5Pb 92.5 Ag 2.5The solder paste is sent to a reflow oven for reflow after screen printing. Set the maximum reflow temperature at 310 °C and hold for 120 s to complete the reflow soldering.

[0127] Table 3 Specification parameters of the silicon carbide power modules prepared with the insulating substrates of Example 1 and Comparative Examples 1 - 3

[0128]

[0129] Perform reflow soldering simulation on the silicon carbide insulating substrates of Example 1 and the insulating substrates of Comparative Examples 1 - 3 to compare the stress and deformation of the insulating substrates after heating. Under the same simulation conditions, the maximum stress of the silicon carbide insulating substrate provided by the present invention after reflow is 1.79E8 N / m 2 , and the maximum stress of the insulating substrate with alumina Al2O3 material as the insulating substrate in Comparative Example 1 is 9.41E8 N / m 2 , and the maximum stress of the insulating substrate with aluminum nitride AlN material as the insulating substrate in Comparative Example 2 is 1.26E9 N / m 2 , and the maximum stress of the insulating substrate with silicon nitride Si3N4 material as the insulating substrate in Comparative Example 3 is 1.41E9 N / m 2 ; the maximum deformation of the silicon carbide insulating substrate provided by the present invention after reflow is 1.29 μm, the maximum deformation of the insulating substrate with Al2O3 material as the insulating substrate is 2.84 μm, the maximum deformation of the insulating substrate with AlN material as the insulating substrate is 2.08 μm, and the maximum deformation of the insulating substrate with Si3N4 material as the insulating substrate is 1.84 μm.

[0130] Figure 3 This is the reflow soldering simulation temperature curve of the silicon carbide insulating substrate of Example 1 of the present invention. As Figure 3 shown, for the welding process, first heat the solder. After reaching the melting point of the solder, cool down to solidify the solder to complete the welding between the substrate and the chip. That is, in the Comsol simulation, imitate this temperature process of reflow soldering. First, the temperature rises from room temperature to 240 °C. At this time, the solder has not melted yet. Then continue to heat up to 340 °C. At this time, the solder melts and then cools down.

[0131] Figure 4 This is the stress distribution diagram of the silicon carbide insulating substrate of Example 1 of the present invention and the insulating substrates of Comparative Examples 1 - 3 after heating. Figure 4 In [figure], a is Example 1, b is Comparative Example 1, c is Comparative Example 2, and d is Comparative Example 3. As Figure 4 shown, by comparison, it can be seen that the silicon carbide insulating substrate proposed by the present invention is subjected to the least force.

[0132] Figure 5 This is the comparison result of the deformation size of the silicon carbide insulating substrate of Example 1 of the present invention and the insulating substrates of Comparative Examples 1 - 3 after reflow soldering.Figure 5 In this, a is Example 1, b is Comparative Example 1, c is Comparative Example 2, and d is Comparative Example 3. As Figure 5 shown, by comparison, it can be seen that the deformation of the silicon carbide insulating substrate proposed by the present invention is the smallest.

[0133] It should be noted that when the present invention involves a numerical range, it should be understood that any value between the two endpoints of each numerical range and any one value between the two endpoints can be selected. Since the adopted step method is the same as that of the embodiment, in order to prevent redundancy, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0134] 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 equivalent technologies, the present invention also intends 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) is 100 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) is 50 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 300 μm; The first metal layer (4) and the second metal layer (5) are both aluminum metal layers.

2. 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).

3. The double-sided aluminum-coated silicon carbide insulating substrate according to claim 2, 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.

4. A method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to any one of claims 1 to 3, 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 50 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 100 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 300 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.

5. The method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to claim 4, characterized in that: The thickness of the surface metallization is 1 μm to 5 μm.

6. The method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to claim 4, characterized in that: The thickness of the sputtering deposited metal copper is 20 μm to 30 μm.

7. The method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to claim 4, 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.

8. The method for preparing a double-sided aluminum-coated silicon carbide insulating substrate according to claim 4, 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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