Metallized ceramic substrate, preparation method thereof and semiconductor device

Abstract

The present invention belongs to the field of semiconductors, and relates to a metallized ceramic substrate, a preparation method thereof, and a semiconductor device. The preparation method of the metallized ceramic substrate provided in the present application includes: a pre-treatment step, pre-treatment of a metal sheet and a ceramic substrate to prepare a substrate precursor having a ceramic layer and a metal layer loaded on the surface of the ceramic layer; a stress relief step, patterning the surface of the metal layer along the thickness direction, forming a wire groove located on the metal layer and recessed toward the thickness direction based on the patterning treatment, sandblasting the surface of the wire groove and / or the surface of the area adjacent to the wire groove to form a stress relief area, and obtaining a stress relief substrate; a post-treatment step, post-treating the stress relief substrate to obtain a metallized ceramic substrate. The metallized ceramic substrate obtained by the preparation method of the present application significantly improves the temperature cycle characteristics and avoids the sacrifice of the metal layer area in the area where the graphics can be printed.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a metallized ceramic substrate, a preparation method thereof, and a semiconductor device. Background Art

[0002] Metallized ceramic substrates, as chip packaging materials, mainly include direct bonded copper (DBC), direct bonded aluminum (DBA), and active metal brazing (AMB).

[0003] DBCs are typically made by sintering copper metal directly onto the surface of a ceramic substrate. As a representative material for metallized ceramic substrates, they are widely used in IGBT chip packaging. Currently, commercial DBCs primarily utilize circuit patterns designed on the metal layer surface to conduct heat and insulate IGBT chips. However, due to the mismatch in thermal expansion coefficients between the metal and ceramic within the metallized ceramic substrate, internal stress can cause separation between the metal and ceramic after cyclic temperature shock, resulting in poor temperature cycling characteristics and reliability.

[0004] In traditional technology, DBC metallized ceramic substrates are mainly improved in the following ways: (1) etching an array of circular pits (i.e., stress release holes) on the metal layers on both sides of the DBC to relieve internal stress; (2) processing a stepped structure on the edges of the graphics on both sides of the DBC to achieve stress gradient changes; (3) using high-strength ceramics (such as ZTA substrates, Si3N4 Improvements to raw material properties, such as substrates (likely referring to a substrate) or small-grain copper, are being made to enhance product strength. However, etching stress relief holes or machining stepped structures inevitably results in a significant loss of metal layer area that could otherwise be used for pattern printing, and the improvement in temperature cycling characteristics is limited. Improving raw material properties significantly increases production costs and fails to reduce the internal stress between the metal and ceramic.

[0005] In view of the above, the present invention is proposed. Summary of the Invention

[0006] The present application provides a metallized ceramic substrate, a preparation method thereof, and a semiconductor device, aiming to solve the above-mentioned problems or at least alleviate the defects existing in the above-mentioned prior art.

[0007] A first aspect of the present application provides a method for preparing a metallized ceramic substrate, comprising:

[0008] A pre-treatment step is to pre-treat the metal sheet and the ceramic substrate to produce a substrate precursor having a ceramic layer and a metal layer supported on the surface of the ceramic layer;

[0009] a stress relief step of patterning the surface of the metal layer along the thickness direction, forming a wire groove located on the metal layer and recessed in the thickness direction based on the patterning, and sandblasting the surface of the wire groove and / or the surface of the area adjacent to the wire groove to form a stress relief area, thereby obtaining a stress-relieved substrate;

[0010] In the post-processing step, the stress-relieved substrate is post-processed to obtain a metallized ceramic substrate.

[0011] The present application designs a preparation method for a metallized ceramic substrate. In a pre-treatment process, a metal sheet and a ceramic substrate are pre-treated to form a substrate precursor. The metal layer and the ceramic layer in the substrate precursor are sequentially stacked and tightly bonded. In a stress relief process, the surface of the metal layer along the thickness direction is patterned. During the patterning process, the surface of the metal layer can be etched to form a groove recessed in the thickness direction on the metal layer. After the surface of the groove and / or the surface of the area adjacent to the groove is sandblasted, the treated area of ​​the metal layer undergoes plastic deformation, that is, loses its elastic deformation ability, to form a stress relief area, thereby obtaining a stress relief substrate. After post-treatment operations such as cleaning and cutting, the outer edge of the obtained metallized ceramic substrate is plastically deformed and loses its elasticity, thereby coordinating and alleviating the internal stress generated by the metallized ceramic substrate during the cyclic temperature shock process, and promoting the close bonding of the metal layer and the ceramic layer of the metallized ceramic substrate after the cyclic temperature shock.

[0012] Therefore, the metallized ceramic substrate prepared by the above preparation method significantly improves the temperature cycling characteristics, avoids the sacrifice of the metal layer area in the area where the graphics can be printed, and compared with the metallized ceramic substrate of the same specifications with traditional etched stress release holes and a stepped structure design, under the same working conditions, the metallized ceramic substrate provided by the present application has an approximately 1.2 to 1.7 times higher thermal shock resistance and an average usable area increased by approximately 10%.

[0013] In the optional scheme of the present application, the stress relief process includes: a first strengthening step: performing a first masking treatment, a first exposure treatment and a first development treatment on the surface of the metal layer along the thickness direction in sequence, so that part of the surface of the metal layer is exposed to the mask along the thickness direction according to a preset path, and then performing a half-etching treatment on the metal layer exposed to the mask part, and performing a first sandblasting treatment on the surface of the first line groove formed based on the half-etching treatment to obtain a sandblasted substrate; a second strengthening step: performing a full etching treatment on the metal layer based on the first line groove path to form a second line groove that can expose the ceramic layer along the thickness direction, and performing a second sandblasting treatment on the surface of the metal layer around the second line groove to form a stress relief area, so as to obtain a stress relief substrate; or, performing a second masking treatment, a second exposure treatment and a second development treatment in sequence on the sandblasted substrate, and exposing the edge part of the metal layer adjacent to the first line groove after the second development treatment to the mask along the thickness direction, and performing a second sandblasting treatment on the surface of the metal layer around the first line groove to form a stress relief area, so as to obtain a stress relief substrate.

[0014] In an optional scheme of the present application, in the first strengthening step, the first sandblasting treatment includes sandblasting the side walls of the first wire groove on the metal layer; in the second strengthening step, before the second sandblasting treatment, it also includes performing a second masking treatment, a second exposure treatment and a second development treatment on the surface of the metal layer where the second wire groove is formed, and the metal layer after the second development treatment is adjacent to the edge of the second wire groove. The portion is exposed to the mask in the thickness direction; and / or, the second sandblasting treatment includes sandblasting the portion of the metal layer exposed to the mask in the thickness direction after the second development treatment.

[0015] In an optional scheme of the present application, the full etching process includes: etching the bottom of the first wire groove to form a second wire groove penetrating the metal layer along the thickness direction; or, etching the edge of the first wire groove and the bottom of the first wire groove to form a second wire groove penetrating the metal layer along the thickness direction, and the edge of the second wire groove is formed with a step recessed along the thickness direction.

[0016] In an optional solution of the present application, post-processing includes sequentially performing mask removal, cleaning, and cutting on the stress-relieved substrate to obtain a metallized ceramic substrate.

[0017] In an optional solution of the present application, the cross-section of the first wire groove along the thickness direction is square; and / or, the first wire groove is arranged in a grid shape along the thickness direction, so that the metal layer is arranged in an array on the ceramic layer after being fully etched.

[0018] In the optional solutions of this application, the preprocessing satisfies any of the following conditions:

[0019] (1) Cleaning and oxidizing the surface of the metal sheet, laminating the metal sheet on a ceramic substrate that has or has not been surface-modified, and sintering the substrate precursor;

[0020] (2) After cleaning the metal sheet and the ceramic substrate, a transition metal or non-metal film is coated on the surface of the metal sheet and / or the ceramic substrate, and the metal sheet is laminated on the ceramic substrate and sintered to form a substrate precursor;

[0021] (3) After cleaning the metal sheet and the ceramic substrate, active metal solder is printed on the surface of the metal sheet and / or the ceramic substrate. After debinding, the metal sheet is stacked on the ceramic substrate and brazed to form a substrate precursor.

[0022] In the optional scheme of the present application, the preparation method satisfies at least one of the following conditions:

[0023] A. The raw material of the metal sheet is a single metal or an alloy obtained by combining multiple metals; optionally, the metal sheet includes at least one metal element selected from copper, aluminum or nickel;

[0024] B. The ceramic substrate includes any one of an alumina ceramic substrate, an aluminum nitride ceramic substrate, a zirconia toughened alumina ceramic substrate, a silicon nitride ceramic substrate or a silicon carbide ceramic substrate;

[0025] C. The mask in the first masking process or the second masking process is a metal protective photosensitive film, and the metal protective photosensitive film includes any one of a negative dry film, a positive dry film, and a wet film;

[0026] D. During the first and second sandblasting processes, the substrate precursor after the half-etching process and the sandblasted substrate after the full-etching process are both fixed by a fixture;

[0027] E. The sand material in the first sandblasting treatment and the second sandblasting treatment is inorganic powder, and the inorganic powder includes at least one of spherical ceramic powder or glass beads; optionally, the particle size of the inorganic powder is 160-200 mesh.

[0028] A second aspect of the present application provides a metallized ceramic substrate, which is manufactured using the above-mentioned preparation method. The metallized ceramic substrate includes a ceramic layer and a metal layer laminated and connected to the surface of the ceramic layer, and the outer edge of the metal layer is a stress relief area.

[0029] A third aspect of the present application provides a semiconductor device comprising the metallized ceramic substrate as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A flow chart of the preparation method exemplified in the embodiments of the present application;

[0032] Figure 2 A cross-sectional view of a metallized ceramic substrate exemplarily provided in an embodiment of the present application;

[0033] Figure 3 A cross-sectional view of a fixture provided as an example in an embodiment of the present application.

[0034] Reference numerals:

[0035] 100. Metallized ceramic substrate;

[0036] 10, ceramic layer; 20, metal layer; R, stress relief area;

[0037] 30. Mask; 40. First wire slot; 50. Second wire slot;

[0038] 200. Fixtures and fixtures;

[0039] 210. Clamp base; 211. Slide groove; 220. Movable support column; 230. Fixing piece; 240. Fastener. DETAILED DESCRIPTION

[0040] The term "half-etching treatment" in this application refers to the use of chemical solutions or physical energy (such as plasma, laser, etc.) to corrode the target area on the surface of the metal layer 20, and after the corrosion treatment, a pattern or structure with a certain depth difference is formed but does not completely penetrate the metal layer 20.

[0041] The term "full etching treatment" in this application refers to the use of chemical solutions or physical energy (such as plasma, laser, etc.) to corrode the target area on the surface of the metal layer 20. After the corrosion treatment, the metal layer 20 in the target area is completely removed, so that the ceramic layer 10 can be exposed through the target area.

[0042] The term “mask 30 ” in this application refers to a protective film covering the surface of a material, which is used to protect or isolate a specific area to prevent the specific area from being affected by the outside or participating in the processing.

[0043] The term "sandblasting" in this application refers to a surface treatment technology that uses high-speed jets of sand to impact the surface of a workpiece.

[0044] As mentioned above, the general inventive concept of the embodiments of the present application is to perform a patterning process such as a half-etching process and / or a full-etching process on the surface of the metal layer 20 along the thickness direction during the preparation process of the metallized ceramic substrate 100, and to perform a sandblasting process on the surface of the wire groove formed after the patterning process and / or the adjacent area, so that the metal layer 20 is locally plastically deformed and loses its elasticity to form a stress relief area R. The stress relief area R can coordinate and relieve the internal stress generated during the cyclic temperature shock process, thereby promoting the close bonding of the metal layer 20 and the ceramic layer 10 of the metallized ceramic substrate 100 after the cyclic temperature shock, thereby improving the reliability of the product, avoiding the sacrifice of the area of ​​the metal layer 20 that could originally be used for printing patterns, and increasing the average usable area of ​​the metallized ceramic substrate 100.

[0045] refer to Figure 1 As shown, the embodiment of the present application provides a method for preparing a metallized ceramic substrate 100, comprising:

[0046] In a pre-treatment step, the metal sheet and the ceramic substrate are pre-treated to form a substrate precursor having a ceramic layer 10 and a metal layer 20 supported on the surface of the ceramic layer 10;

[0047] In a stress relief process, the surface of the metal layer 20 along the thickness direction is patterned to form a groove located on the metal layer 20 and recessed in the thickness direction based on the patterning process. The surface of the groove and / or the surface of the area adjacent to the groove is sandblasted to form a stress relief area R, thereby obtaining a stress-relieved substrate.

[0048] In the post-processing step, the stress-relieved substrate is post-processed to obtain the metallized ceramic substrate 100 .

[0049] It should be noted that, in the pre-treatment process of the embodiment of the present application, during the pre-treatment of the metal sheet and the ceramic substrate, the metal sheet and the ceramic substrate can be cleaned separately, or the metal sheet or the ceramic substrate can be surface-modified separately to ensure that the surface state of the metal sheet and the ceramic substrate before bonding reaches the best, so as to improve the bonding strength of subsequent stacking and sintering. After that, the metal sheet and the ceramic plate are stacked and fired into an integrated substrate precursor. In the substrate precursor, the ceramic layer 10 introduced by the ceramic plate is loaded with a metal layer 20 introduced by the metal sheet on at least one side along the thickness direction, and the metal layer 20 is tightly combined with the ceramic layer 10 to facilitate the processing of subsequent processes.

[0050] Furthermore, in the stress relief process, the metal layer 20 is patterned along the thickness direction to form a groove, and the surface of the groove and / or the surface of the area adjacent to the groove is sandblasted to form a stress relief area R. The sandblasting can change the microstructure of the metal surface, causing the sandblasted area to undergo plastic deformation, thereby suppressing the stress generated in this part during the cyclic thermal shock process, and obtaining a stress-relieved substrate. After further post-processing such as cleaning and cutting of the stress-relieved substrate, the stress relief area R on the obtained metallized ceramic substrate 100 is located at the outer edge of the metal layer 20. The presence of the stress relief area R helps to absorb and disperse the stress generated by the metallized ceramic substrate 100 during temperature changes, thereby improving the overall thermal shock resistance of the product, thereby avoiding separation of the metal layer 20 and the ceramic layer 10 due to internal stress, thereby significantly improving the service life and reliability of the product.

[0051] Furthermore, the surface of the metallized ceramic substrate 100 in the embodiment of the present application does not include stress relief holes or other structures that require sacrificing the printed pattern area of ​​the metal layer 20, thereby significantly increasing the average usable area of ​​the metallized ceramic substrate 100. Compared with conventional metallized ceramic substrates 100 with etched stress relief holes and a stepped structure design of the same specifications, under the same operating conditions, the metallized ceramic substrate 100 provided in the embodiment of the present application has a thermal shock resistance increased by approximately 1.2 to 1.7 times, and an average usable area increased by approximately 10%.

[0052] In some embodiments, the stress relief process specifically includes: a first strengthening step: performing a first mask 30 treatment, a first exposure treatment, and a first development treatment on the surface of the metal layer 20 along the thickness direction in sequence, so that part of the surface of the metal layer 20 is exposed to the mask 30 along the thickness direction according to a preset path, and then performing a half-etching treatment on the metal layer 20 exposed to the mask 30. The surface of the first linear groove 40 formed based on the half-etching treatment is subjected to a first sandblasting treatment to obtain a sandblasted substrate; a second strengthening step: performing a full etching treatment on the metal layer 20 based on the first linear groove 40 path to form a second linear groove 50 that can expose the ceramic layer 10 along the thickness direction, and performing a second sandblasting treatment on the surface of the metal layer 20 around the second linear groove 50 to form a stress relief area R to obtain a stress relief substrate.

[0053] In the first strengthening step, the metal layer 20 exposed to the mask 30 is half-etched along the thickness direction, so that the metal layer 20 forms a first groove 40 along the thickness direction. Since the first groove 40 is formed by the half-etching process, it has a blind groove structure, that is, the bottom of the first groove 40 does not penetrate the metal layer 20. By sandblasting the surface of the first groove 40, the metal material on the surface of the first groove 40 can be plasticized and deformed, reducing its elastic state, thereby enhancing the stability of the metal layer 20 and obtaining a sandblasted substrate; wherein, the sandblasting process helps to suppress the internal stress generated by the cyclic temperature shock of the metallized ceramic substrate 100. Since the sandblasting process is based on the surface of the first groove 40, the metal layer 20 at the bottom of the first groove 40 can also prevent damage to the ceramic layer 10 during the sandblasting process, thereby improving the reliability of the subsequently manufactured product.

[0054] It should be noted that, in the first strengthening step of the embodiment of the present application, before the metal layer 20 is half-etched, the surface of the metal layer 20 is sequentially subjected to a first mask 30 treatment, a first exposure treatment, and a first development treatment. The mask 30 used in the first mask 30 treatment may be a photosensitive mask 30 (photoresist). This photosensitive mask 30 is pre-designed with an area pattern corresponding to a preset path. After the first exposure treatment, light of a specific wavelength (such as ultraviolet light) penetrates the transparent area, causing the photoresist to undergo a chemical reaction. Subsequently, in the first development treatment, the developer selectively dissolves the reacted photoresist portion, exposing the preset path area on the metal layer 20, in preparation for the subsequent half-etching treatment. These exposed areas are where the first line grooves 40 will be etched to form in the subsequent half-etching treatment, so as to facilitate the precise positioning of the first line grooves 40.

[0055] In the second strengthening step, the metal layer 20 is fully etched based on the path of the first wire groove 40, so that the metal material at the bottom of the first wire groove 40 can be completely removed, thereby forming a second wire groove 50 with a greater depth than the first wire groove 40. The ceramic layer 10 can be exposed through the second wire groove 50 in the thickness direction. By sandblasting the surface of the metal layer 20 around the second wire groove 50, the plastic deformation degree of the metal material around the second wire groove 50 can be further deepened, thereby forming a stress relief area R to obtain a stress-relieved substrate; after further post-processing such as cleaning and cutting of the stress-relieved substrate, the stress relief area R on the obtained metallized ceramic substrate 100 is located at the outer edge of the metal layer 20. The presence of the stress relief area R helps to absorb and disperse the stress generated by the metallized ceramic substrate 100 during temperature changes, thereby improving the overall thermal shock resistance of the product, thereby avoiding separation of the metal layer 20 and the ceramic layer 10 due to internal stress, thereby significantly improving the service life and reliability of the product.

[0056] Furthermore, in the second strengthening step of the embodiment of the present application, before the sandblasting treatment, the surface of the metal layer 20 on which the second linear groove 50 is formed is subjected to a mask removal 30 treatment, a second mask 30 treatment, a second exposure treatment and a second development treatment in sequence. The mask removal 30 treatment can remove the mask 30 used to form the first linear groove 40 in the first strengthening process, exposing the complete surface of the metal layer 20. After the second mask 30 treatment, a new photosensitive mask 30 (photoresist) is re-attached to the surface of the metal layer 20. This mask 30 is designed with patterns corresponding to areas that require further processing (such as specific portions of the edge of the second linear groove 50). In the second exposure process, light of a specific wavelength (such as ultraviolet light) is used to expose the new photosensitive mask 30. The light passes through the transparent area on the mask 30 and selectively irradiates predetermined positions on the surface of the metal layer 20, causing a chemical reaction in the photoresist at these positions. Subsequently, in the second development process, the exposed metal layer 20 is placed in a developer, which selectively dissolves the photoresist portion that is exposed to light (or not exposed to light, depending on the type of photoresist). After the second development process, the portion of the metal layer 20 adjacent to the edge of the second linear groove 50 will be exposed along the thickness direction. This portion is the target area for the subsequent sandblasting process.

[0057] As a result, the metal materials on the side walls and edge portions of the second wire groove 50 are plastically deformed to form a stress relief area R. After cutting the ceramic layer 10 along the second wire groove 50 in the thickness direction in subsequent post-processing, the stress relief area R is formed on the outer edge of the metal layer 20 on the obtained metallized ceramic substrate 100, thereby significantly improving the bonding performance between the metal layer 20 and the ceramic layer 10 during the cyclic temperature shock process and improving product reliability.

[0058] In some embodiments, in order to prevent the ceramic layer 10 from being exposed and meet diverse application requirements, in the second strengthening step, the sandblasted substrate obtained based on the first strengthening step is sequentially subjected to a second mask 30 treatment, a second exposure treatment, and a second development treatment, and the edge portion of the metal layer 20 adjacent to the first wire groove 40 after the second development treatment is exposed to the mask 30 along the thickness direction, and the surface of the metal layer 20 around the first wire groove 40 is subjected to a second sandblasting treatment to form a stress relief area R, thereby obtaining a stress relief substrate.

[0059] It can be understood that in this embodiment, during the second strengthening step, the bottom of the first wire groove 40 is not fully etched. After the sandblasted substrate obtained based on the first strengthening step is subjected to the second mask 30 treatment, the second exposure treatment and the second development treatment in sequence, the edge portion of the first wire groove 40 is exposed to the mask 30 along the thickness direction, that is, the edge of the top surface of the first wire groove 40 has a preset distance from the mask 30. Subsequently, the surface of the metal layer 20 around the first wire groove 40 (that is, the portion of the first wire groove 40 exposed to the mask 30 along the thickness direction and / or the inner wall of the first wire groove 40) is subjected to a second sandblasting treatment to form a stress relief area R to obtain a stress relief substrate; after further post-processing such as cleaning and cutting of the stress relief substrate, the stress relief area R on the obtained metallized ceramic substrate 100 is located at the outer edge of the metal layer 20, which significantly improves the service life and reliability of the product.

[0060] The purpose of the sandblasting in the embodiments of the present application is to promote plastic deformation of the metal material in the target area. In some embodiments, the first sandblasting in the first strengthening step includes sandblasting the side wall of the first wire groove 40 on the metal layer 20. The sandblasting is performed by high-pressure spraying of fine sand particles or similar abrasives to impact and cut the side wall of the first wire groove 40 (i.e., the thickness surface of the metal layer 20), thereby forming a dense hardened layer on its surface and near the adjacent surface to overcome the elastic deformation caused by internal stress and cause separation from the ceramic layer 10.

[0061] In some embodiments, in the second strengthening step, before the second sandblasting treatment, the surface of the metal layer 20 formed with the second linear groove 50 is also subjected to a second mask 30 treatment, a second exposure treatment and a second development treatment in sequence, and the edge portion of the metal layer 20 adjacent to the second linear groove 50 after the second development treatment is exposed to the mask 30 along the thickness direction, so as to facilitate sandblasting of the spacing area between the top of the second linear groove 50 and the mask 30.

[0062] In some embodiments, the second sandblasting treatment includes sandblasting the portion of the metal layer 20 exposed to the mask 30 along the thickness direction after the second development treatment. After the second development treatment, the portion of the metal layer 20 adjacent to the edge of the second wire groove 50 is exposed outside the mask 30 along the thickness direction. In order to harden this area, sandblasting is also used. Sandblasting can cause the metal material in the exposed area to undergo plastic deformation to form a hardened layer. Combined with sandblasting, the heat shock resistance of the outer edge of the metal layer 20 on the metallized ceramic substrate 100 can be significantly improved.

[0063] In some embodiments, the second sandblasting process includes sandblasting the inner wall of the second wire groove 50 to further deepen the plastic deformation of the outer edge of the metal layer 20 .

[0064] During the sandblasting process in the embodiment of the present application, the metal surface of the target area is sandblasted until it is in a hardened state. That is to say, after sandblasting, obvious deformation can be observed in the target area in its natural state. At this time, the metal surface of the target area after sandblasting reaches a plastic deformation state and loses its elasticity.

[0065] In some embodiments, the full etching process includes: etching the bottom of the first wire groove 40 to form a second wire groove 50 that penetrates the metal layer 20 along the thickness direction, and there is no step at the top of the second wire groove 50, that is, the entire surface of the metal layer 20 can be used as a pattern printing area, thereby increasing the average usage area of ​​the product.

[0066] In some embodiments, in order to further improve the temperature cycling characteristics of the metallized ceramic substrate 100, the full etching process includes: etching the edge and bottom of the first groove 40 to form a second groove 50 that penetrates the metal layer 20 in the thickness direction, and forming a step recessed in the thickness direction at the edge of the second groove 50. By forming a step recessed in the thickness direction at the edge of the second groove 50, a buffer area can be further provided for the release of internal stress. Combined with the plastic deformation of the surface of the metal layer 20 at the sidewall and edge of the second groove 50, the thermal shock resistance of the metallized ceramic substrate 100 can be greatly improved, but the area that can be used for pattern printing will be slightly sacrificed.

[0067] In some embodiments, the post-processing includes sequentially performing mask removal 30 , cleaning, and cutting on the stress-relieved substrate to obtain the metallized ceramic substrate 100 .

[0068] It is understood that after stress relief, a photosensitive mask 30 used for patterning the metal layer 20 is usually retained on the substrate during post-processing. This mask 30 needs to be removed after completing its mission to expose the complete surface of the metal layer 20. After further cleaning methods such as ultrasonic cleaning, high-pressure water washing, or chemical cleaning are used to remove any remaining mask 30 fragments, chemical solvents, or other contaminants on the surfaces of the metal layer 20 and the ceramic layer 10, it is usually necessary to cut according to the size and shape of the final product. This step is to divide the large block of material into multiple independent metallized ceramic substrates 100 products for subsequent assembly and application. The cutting process can be carried out by mechanical cutting (such as diamond saw blade cutting), laser cutting, or water jet cutting, and the cutting is carried out vertically along the second linear groove 50 so that the stress relief area R on the metallized ceramic substrate 100 is formed on the outer edge of the metal layer 20.

[0069] In some embodiments, the cross-section of the first wire groove 40 along the thickness direction is square, so as to facilitate sandblasting of the side wall of the first wire groove 40. At the same time, the cross-section of the second wire groove 50 along the thickness direction is a square with a larger size, so as to further deepen the degree of plastic deformation of the surface of the metal layer 20.

[0070] In some embodiments, the first wire grooves 40 are arranged in a grid pattern along the thickness direction, so that the metal layer 20 is arranged in an array on the ceramic layer 10 after being fully etched, which is beneficial for dividing the entire stress-relieved substrate into multiple independent metallized ceramic substrates 100 products during subsequent post-processing and cutting, thereby improving the product yield and material utilization rate.

[0071] In some embodiments, the pretreatment process in the pre-treatment step can be a DBC process, a DBA process, or an AMB process, depending on the material selection of the metal layer 20 and the ceramic layer 10. All of these processes can provide a substrate precursor that meets the processing conditions for the first strengthening process. Specifically, when the DBC process is used for pretreatment, the surface of the metal sheet (usually a copper sheet) is cleaned and oxidized during the pretreatment process. The metal sheet is then stacked on a ceramic substrate that has or has not undergone surface modification and sintered to form a substrate precursor. The ceramic substrate may be surface-modified to improve wettability depending on the specific situation. When the DBA process is used for pretreatment, after the metal sheet and ceramic substrate are cleaned, a transition metal or non-metallic film is coated on the surface of the metal sheet and / or ceramic substrate to facilitate subsequent overall sintering. After coating with the transition metal or non-metallic film, the metal sheet is stacked on the ceramic substrate and sintered to form a substrate precursor. When the AMB process is used for pretreatment, the metal sheet and the ceramic substrate are cleaned, and then active metal solder is printed on the surface of the metal sheet and / or the ceramic substrate. After debinding, the metal sheet is laminated on the ceramic substrate and brazed to form a substrate precursor.

[0072] In some embodiments, the raw material of the metal sheet may be a single metal or an alloy obtained by combining multiple metals; specifically, the metal sheet may include at least one metal element selected from copper, aluminum, or nickel.

[0073] In some embodiments, the ceramic substrate comprises an alumina ceramic substrate (Al2O3) , any one of aluminum nitride ceramic substrate (AlN), zirconia toughened alumina ceramic substrate (ZTA), silicon nitride ceramic substrate (Si3N4), and silicon carbide ceramic substrate (SiC).

[0074] In some embodiments, the mask 30 in the first mask 30 process or the second mask 30 process is a metal protective photosensitive film, which includes any one of a negative dry film, a positive dry film, and a wet film. In the case of a negative dry film, after exposure, the portion not exposed to light (i.e., the patterned portion of the mask 30) is dissolved during the development process, while the portion exposed to light remains, forming the desired pattern. In the case of a positive dry film, after exposure, the portion exposed to light (i.e., the patterned portion of the mask 30) is dissolved during the development process, while the portion not exposed to light remains. A wet film is a liquid photoresist that needs to be coated on the surface of the metal layer 20 and cured by drying. The coating thickness can be adjusted as needed, and the coating can be performed by spin coating, spray coating, or brush coating.

[0075] In some embodiments, the second exposure process can be flexibly designed according to the different metal protective photosensitive films used. For example, when a negative dry film is used as the mask 30 in the first mask 30 process, the negative dry film covering the metal layer 20 needs to be removed before the second film process, and then the second film process, the second exposure process and the second development process are performed in sequence to expose the position requiring subsequent processing for direct processing; when a positive dry film is used as the mask 30 in the first mask 30 process, the positive dry film covering the metal layer 20 does not need to be removed before the second film process, and the positive dry film is exposed during the exposure process. After exposure and development, the exposed part will be dissolved, while the unexposed part will remain. Therefore, the positive dry film covering the metal layer 20 usually does not need to be removed, and the second exposure treatment and the second development treatment are directly performed to expose the position requiring subsequent processing for direct processing; when a wet film is used as the mask 30 in the first mask 30 treatment process, the mask 30 covering the metal layer 20 needs to be removed before the second film treatment, and then the second film treatment (printing wet film), the second exposure treatment and the second development treatment are performed in sequence to expose the position requiring subsequent processing for direct processing.

[0076] In some embodiments, during the first sandblasting process and the second sandblasting process, the substrate precursor after the half-etching process and the sandblasted substrate after the full-etching process are both fixed by the fixture 200. The fixture 200 can support and protect the processed materials to improve the precision of the sandblasting process and the sandblasting process, so that the stress relief area R can be formed at the preset target position.

[0077] As an example, the structure of the fixture 200 is as follows: Figure 3As shown, it includes a clamp base 210, a plurality of movable support columns 220, a fixing member 230 and a fastener 240. A processing space is formed in the clamp base 210, and a slide groove 211 is designed at the bottom of the processing space. A plurality of movable support columns 220 are arranged at intervals in the slide groove 211. The bottom of the movable support column 220 is slidably connected to the slide groove 211 and can move along the extension direction of the slide groove 211. The top of the movable support column 220 is fixedly connected to the fixing member 230. The two ends of the fixing member 230 are plugged into the clamp base 210. The fastener 240 passes through the two ends of the clamp base 210 and the fixing member 230 in the axial direction. The ends are screwed, and the ceramic layer 10 in the substrate precursor after half etching or the substrate after sandblasting after full etching is clamped and fixed by the fixing part 230 and is located between two adjacent movable support columns. By rotating the fastener 240 axially, the fixing part 230 can be moved along the axial direction of the fastener 240 to adjust the height position of the substrate precursor after half etching or the substrate after sandblasting after full etching, and the horizontal position of the substrate precursor after half etching or the substrate after sandblasting after full etching is adjusted by sliding the two adjacent movable support columns, so that the position processed during sandblasting and sandblasting is more precise.

[0078] In some embodiments, the sand material in the sandblasting process is an inorganic powder. The inorganic powder has the advantages of high hardness, good wear resistance, and strong chemical stability, and is suitable for use as a sandblasting material. The inorganic powder includes at least one of spherical ceramic powder or glass beads; the particle size of the inorganic powder is 160~200 mesh, preferably 180 mesh.

[0079] In some embodiments, the first sandblasting and / or the second sandblasting may be performed by directly sandblasting using a dry sandblasting machine, or by using a horizontal or vertical line sandblasting device containing sand particles with a solution to harden the surface of the metal layer 20 .

[0080] refer to Figure 2 As shown, another embodiment of the present application provides a metallized ceramic substrate 100, which is manufactured using the above-mentioned preparation method. The metallized ceramic substrate 100 includes a ceramic layer 10 and a metal layer 20 stacked and connected to the surface of the ceramic layer 10. The outer edge of the metal layer 20 is a stress relief area R.

[0081] Another embodiment of the present application provides a semiconductor device, including the metallized ceramic substrate 100 as described above.

[0082] The following examples further describe the present disclosure. These examples are intended for illustrative purposes only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all reagents and starting materials used in the examples are commercially available or synthesized according to conventional methods, and all instruments used in the examples are commercially available.

[0083] Example 1

[0084] (1) Pretreatment process: After ultrasonic cleaning of the copper sheet and the alumina ceramic substrate, the copper sheet is oxidized. The specifications of the copper sheet are 138*184*0.30 (mm), and the specifications of the alumina ceramic substrate are 138*190*0.38 (mm). The copper sheet and the alumina ceramic substrate are stacked and sintered to obtain a substrate precursor through the DBC process;

[0085] (2) Stress relief process:

[0086] ① First strengthening step: The copper layer is sequentially subjected to a first mask 30 treatment, a first exposure treatment, a first development treatment, and a half-etching treatment to form a first wire groove 40 on the copper layer. The first wire groove 40 is in a grid pattern with a size of 55*24 (mm) and an arrangement matrix of 5 rows and 3 columns. The surface of the first wire groove 40 is sandblasted, and the bottom and side walls of the first wire groove 40 are sandblasted until plastic deformation occurs, thereby obtaining a sandblasted substrate. The inorganic powder used for sandblasting is spherical ceramic powder with a particle size of approximately 180 mesh.

[0087] ② The second strengthening step: the copper layer at the bottom of the first wire groove 40 is fully etched to remove all the copper layers at the bottom of the first wire groove 40 to form a second wire groove 50, and then the photosensitive mask 30 on the surface of the copper layer is removed. Subsequently, the second mask 30 treatment, the second exposure treatment, and the second development treatment are sequentially performed on the surface of the copper layer, and the distance between the edge of the mask 30 and the edge of the second wire groove 50 is made to be 0.6 mm. Subsequently, the surface of the copper layer exposed outside the mask 30 is sandblasted until the surface of the target position is hardened to obtain a stress-relieved substrate; the inorganic powder used for sandblasting is spherical ceramic powder with a particle size of about 180 mesh.

[0088] (3) Post-processing: Remove the photosensitive mask 30 on the copper layer surface of the substrate after stress relief, then use ultrasonic cleaning, and use laser cutting technology to cut along the center of the bottom of the second line groove 50 in the thickness direction to obtain 3*5=15 stress relief sheets. Al2O3-DBC Metallized ceramic substrate 100 .

[0089] Example 2

[0090] (1) Pretreatment process: After ultrasonic cleaning of the copper sheet and the aluminum nitride ceramic substrate, the copper sheet is oxidized and the aluminum nitride ceramic substrate is surface modified. The specifications of the copper sheet are 134*184*0.30 (mm), and the specifications of the aluminum nitride ceramic substrate are 138*190*0.635 (mm). Through the DBC process, the copper sheet and the aluminum nitride ceramic substrate are stacked and sintered to obtain a substrate precursor;

[0091] (2) Stress relief process:

[0092] ① First strengthening step: The copper layer is sequentially subjected to a first mask 30 treatment, a first exposure treatment, a first development treatment, and a half-etching treatment to form a first wire groove 40 on the copper layer. The first wire groove 40 is in a grid pattern with a size of 60.4*26.8 (mm) and an arrangement matrix of 6 rows and 2 columns. The substrate precursor after the half-etching treatment is loaded into a fixture 200, and the surface of the first wire groove 40 is sandblasted. The bottom and side walls of the first wire groove 40 are sandblasted until plastic deformation occurs, thereby obtaining a sandblasted substrate. The inorganic powder used for sandblasting is spherical alumina ceramic powder with a particle size of approximately 180 mesh.

[0093] ② The second strengthening step: remove the photosensitive mask 30 on the surface of the copper layer on the sandblasted substrate, and then perform a second mask 30 treatment, a second exposure treatment, and a second development treatment on the surface of the copper layer in sequence, and make the distance between the edge of the mask 30 and the edge of the first wire groove 40 be 1.5 mm, and load the sandblasted substrate after the second development treatment into the fixture 200, and then sandblast the surface of the copper layer exposed outside the mask 30 until the surface of the target position is hardened to obtain a stress-relieved substrate; the inorganic powder used for sandblasting is spherical ceramic powder with a particle size of about 180 mesh.

[0094] (3) Post-processing step: remove the photosensitive mask 30 on the surface of the copper layer on the stress-relieved substrate, then use ultrasonic cleaning, and use laser cutting technology to cut along the thickness direction along the center of the bottom of the first line groove 40 to obtain 2*6=12 stress-relieved AlN-DBC metallized ceramic substrates 100.

[0095] Example 3

[0096] (1) Pretreatment process: After ultrasonic cleaning of the copper sheet and the aluminum nitride ceramic substrate, the copper sheet is oxidized and the aluminum nitride ceramic substrate is surface modified. The specifications of the copper sheet are 134*184*0.30 (mm), and the specifications of the aluminum nitride ceramic substrate are 138*190*0.635 (mm). Through the DBC process, the copper sheet and the aluminum nitride ceramic substrate are stacked and sintered to obtain a substrate precursor;

[0097] (2) Stress relief process:

[0098] ① First strengthening step: The copper layer is sequentially subjected to a first mask 30 treatment, a first exposure treatment, a first development treatment, and a half-etching treatment to form a first wire groove 40 on the copper layer. The first wire groove 40 has a grid pattern with a size of 25.5*56.5 (mm), a matrix arrangement of 3 rows and 5 columns, and an etching depth of 0.15 mm; the surface of the first wire groove 40 is sandblasted, and the side walls of the first wire groove 40 are sandblasted until plastic deformation occurs, thereby obtaining a sandblasted substrate; the inorganic powder used for sandblasting is spherical alumina ceramic powder with a particle size of approximately 180 mesh;

[0099] ② The second strengthening step: remove the photosensitive mask 30 on the surface of the copper layer on the substrate after sandblasting, and then perform a second mask 30 treatment, a second exposure treatment, and a second development treatment on the surface of the copper layer in sequence, and make the distance between the edge of the mask 30 and the edge of the first wire groove 40 be 2 mm, and perform a full etching treatment on the copper layer at the bottom of the first wire groove 40. After removing all the copper layers at the bottom of the first wire groove 40, a second wire groove 50 is formed. After the full etching treatment, a step is formed on the edge of the second wire groove 50 that is concave in the thickness direction, and the step depth is 0.15 mm. Then, the surface of the copper layer exposed outside the mask 30 is sandblasted until the surface of the target position is hardened to obtain a stress-relieved substrate; the inorganic powder used for sandblasting is spherical ceramic powder with a particle size of about 180 mesh.

[0100] (3) Post-processing step: remove the photosensitive mask 30 on the surface of the copper layer on the stress-relieved substrate, then use ultrasonic cleaning, and use laser cutting technology to cut along the thickness direction along the center of the bottom of the first line groove 40 to obtain 3*5=15 stress-relieved AlN-DBC metallized ceramic substrates 100.

[0101] The technical features described above can be combined arbitrarily. Although not all possible combinations of these technical features are described, any combination of these technical features should be considered to be covered by this specification, as long as there is no contradiction in such combination. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a metallized ceramic substrate, characterized in that: include: A pre-treatment step of pre-treating the metal sheet and the ceramic substrate to prepare a substrate precursor having a ceramic layer and a metal layer supported on the surface of the ceramic layer; A stress relief process, patterning the surface of the metal layer along the thickness direction, forming a wire groove located on the metal layer and recessed in the thickness direction based on the patterning, and sandblasting the surface of the wire groove and / or the surface of the adjacent area of ​​the wire groove so that the sandblasted area of ​​the metal layer loses elastic deformation ability to form a stress relief area, thereby obtaining a stress-relieved substrate; The post-processing step is to post-process the stress-relieved substrate to obtain a metallized ceramic substrate; wherein the stress-relieved area on the metallized ceramic substrate is located at the outer edge of the metal layer.

2. The preparation method according to claim 1, characterized in that: The stress relief process comprises: A first strengthening step: sequentially performing a first masking process, a first exposure process, and a first development process on the surface of the metal layer along the thickness direction, so that a portion of the surface of the metal layer is exposed to the mask along the thickness direction according to a preset path, and then performing a half-etching process on the metal layer exposed to the mask portion, and performing a first sandblasting process on the surface of the first line groove formed by the half-etching process to obtain a sandblasted substrate; The second strengthening step: based on the first groove path, the metal layer is fully etched to form a second groove that can expose the ceramic layer in the thickness direction, and the surface of the metal layer around the second groove is subjected to a second sandblasting treatment to form a stress relief area to obtain a stress relief substrate; or, based on the sandblasted substrate, a second masking treatment, a second exposure treatment and a second development treatment are sequentially performed, and the edge portion of the metal layer adjacent to the first groove after the second development treatment is exposed to the mask in the thickness direction, and the surface of the metal layer around the first groove is subjected to a second sandblasting treatment to form a stress relief area to obtain a stress relief substrate.

3. The preparation method according to claim 2, characterized in that: In the first strengthening step, the first sandblasting process includes sandblasting the sidewall of the first wire groove on the metal layer; In the second strengthening step, before the second sandblasting treatment, the second step further includes sequentially performing a second masking treatment, a second exposure treatment and a second development treatment on the surface of the metal layer formed with the second wire groove, and exposing the edge portion of the metal layer adjacent to the second wire groove after the second development treatment to the mask in the thickness direction; And / or, the second sandblasting process includes sandblasting a portion of the metal layer exposed to the mask in a thickness direction after the second development process.

4. The preparation method according to claim 3, characterized in that: The full etching process includes: Etching the bottom of the first wire groove to form a second wire groove penetrating the metal layer in a thickness direction; Alternatively, the edge of the first wire groove and the bottom of the first wire groove are etched to form a second wire groove penetrating the metal layer in the thickness direction, and a step recessed in the thickness direction is formed at the edge of the second wire groove.

5. The preparation method according to claim 3, characterized in that: The post-processing includes sequentially performing mask removal, cleaning and cutting along the line grooves on the stress-relieved substrate to obtain a metallized ceramic substrate.

6. The preparation method according to claim 5, characterized in that: The cross section of the first wire groove along the thickness direction is square; and / or, The first wire grooves are arranged in a grid shape along the thickness direction, so that the metal layer is arranged in an array on the ceramic layer after being fully etched.

7. The preparation method according to claim 3, characterized in that: The pre-processing satisfies any of the following conditions: (1) cleaning and oxidizing the surface of a metal sheet, laminating the metal sheet on a ceramic substrate that has been or has not been surface-modified, and sintering the substrate precursor; (2) After cleaning the metal sheet and the ceramic substrate, covering the surface of the metal sheet and / or the ceramic substrate with a transition metal or non-metal film, and stacking the metal sheet on the ceramic substrate and sintering to form a substrate precursor; (3) After cleaning the metal sheet and the ceramic substrate, active metal solder is printed on the surface of the metal sheet and / or the ceramic substrate. After debinding treatment, the metal sheet is stacked on the ceramic substrate and brazed to form a substrate precursor.

8. The preparation method according to any one of claims 3 to 7, characterized in that The preparation method satisfies at least one of the following conditions: A. The raw material of the metal sheet is a single metal or an alloy obtained by combining multiple metals; the metal sheet includes at least one metal element selected from copper, aluminum or nickel; B. The ceramic substrate includes any one of a ceramic alumina ceramic substrate, an aluminum nitride ceramic substrate, a zirconia toughened alumina ceramic substrate, a silicon nitride ceramic substrate or a silicon carbide ceramic substrate; C. The mask in the first masking process or the second masking process is a metal protective photosensitive film, and the metal protective photosensitive film includes any one of a negative dry film, a positive dry film, and a wet film; D. During the first sandblasting process and the second sandblasting process, the substrate precursor after the half-etching process and the sandblasted substrate after the full-etching process are both fixed by a fixture; E. The sand material in the first sandblasting and the second sandblasting is inorganic powder, and the inorganic powder includes at least one of spherical ceramic powder or glass beads; the particle size of the inorganic powder is 160~200 mesh.

9. A metallized ceramic substrate, characterized in that: The metallized ceramic substrate is prepared by the preparation method according to any one of claims 1 to 8, wherein the metallized ceramic substrate comprises a ceramic layer and a metal layer laminated and connected to the surface of the ceramic layer, and the outer edge of the metal layer is a stress relief area.

10. A semiconductor device, characterized in that: Comprising the metallized ceramic substrate as claimed in claim 9.

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