Semiconductor device and method for manufacturing the same

Abstract

The present invention suppresses unnecessary stress on the members that constitute a device.　A semiconductor device (10) comprises a base plate (2), a semiconductor element (1), protection members (pr1a, pr1b, pr2a, pr2b), and a cooling body (3). The base plate (2) includes a silicon carbide molded body (2a) and metal filling bodies (2b1, 2b2), and through holes are provided in the metal filling bodies (2b1, 2b2). The semiconductor element (1) is mounted on an upper surface of the silicon carbide molded body (2a) with an insulating substrate (12) therebetween. The protection members (pr1a, pr1b, pr2a, pr2b) are formed on the surface of the metal filling bodies (2b1, 2b2) and have a lower hardness than the silicon carbide molded body (2a). The cooling body (3) is adhered to a bottom surface side of the base plate (2) and is fastened to the base plate (2) by screws (sc1, sc2) that have been passed through the through holes.

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device. [Background technology]

[0002] In recent years, silicon carbide (SiC) molded bodies made of silicon carbide and metal composites have been used as heat dissipation base plates for power semiconductor modules. Silicon carbide molded bodies are manufactured by impregnating a sintered silicon carbide molded body with a metal composite.

[0003] In the power semiconductor module, the heat sink is attached to the heat sink base plate with screws, etc. In this case, the heat sink base plate is provided with through holes for fastening the heat sink with screws.

[0004] When through holes are drilled in the silicon carbide formed body of the heat dissipating base plate, the high hardness of the silicon carbide formed body makes it difficult to perform cutting processes such as punching, which are used to drill holes in ordinary metal bases, and special processes such as water jet machining are required. However, because special processes such as water jet machining are costly, a heat dissipating base plate made of a single metal material is used in the area where the through holes are to be formed.

[0005] As related art, for example, a heat dissipation component has been proposed in which the outer periphery of a through hole is a metal portion made of aluminum or an alloy thereof, and the rest is made of an aluminum-silicon carbide composite material (Patent Document 1). Also proposed is a heat spreader composed of a coating layer and a frame, with a groove on either the front or back surface that follows the outer edge of the internal substrate. Furthermore, a semiconductor module has been proposed that has a heat sink attached to a base plate, which is a cooling body made of MgSiC, via thermal paste and a metal ring (Patent Document 3). Still further, a bonded substrate has been proposed in which a thinned portion is formed at the opening of a through hole in a metal base plate, and a metal reinforced film is formed on the thinned portion (Patent Document 4). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-204022 [Patent Document 2] International Publication No. 2009 / 098865 [Patent Document 3] Japanese Patent Application Publication No. 2018-181893 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-187009 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, the single metal material in the region where the through holes are provided has the advantage of being easy to cut, but in the heat dissipating base plate, a step may occur between the silicon carbide forming body and the metal material due to the difference in the linear expansion coefficients of the silicon carbide forming body and the metal material, and if the cooling body is fastened to the heat dissipating base plate through the through holes with the step in place, unnecessary stress will be generated in each member constituting the power semiconductor module due to the principle of leverage. In one aspect, the present invention aims to provide a semiconductor device and a method for manufacturing the semiconductor device that suppress the generation of unnecessary stress on the components that make up the device. [Means for solving the problem]

[0008] To solve the above problems, a semiconductor device is provided. The semiconductor device includes a base plate, a semiconductor element, a protective member, and a cooling body. The base plate has a silicon carbide forming body and a metal filling body, and a through hole is formed in the metal filling body. The semiconductor element is mounted on the upper surface of the base plate via an insulating substrate. The protective member is formed on the surface of the metal filling body and has a hardness lower than that of the silicon carbide forming body. The cooling body is attached to the bottom side of the base plate and is fastened to the base plate by screws that pass through the through holes. In addition, the protective member is a metal plate or an elastic material, the material of the metal plate is either Cu, Al, or Fe, and the elastic material is tape, the thermal conductivity of which is equal to or greater than that of the thermal compound provided between the base plate and the cooling body. In order to solve the above-mentioned problems, a method for manufacturing a semiconductor device is also provided, which includes: forming a silicon carbide formed body by sintering silicon carbide in a portion avoiding a predetermined region, and pouring a melt of a metal composite material into the sintered silicon carbide and the predetermined region; Formed by filling a specified area with a molten metal composite material a metal filler; a base plate having the metal filler; a through hole formed by cutting the metal filler; a protective member having a hardness lower than that of the silicon carbide body formed on a surface of the metal filler; and a semiconductor element mounted on the upper surface of the base plate via an insulating substrate. The cooling body is attached to the bottom side of the base plate and fastened to the base plate by screws inserted into the through holes. do. In addition, the protective member is a metal plate or an elastic material, the material of the metal plate is either Cu, Al, or Fe, and the elastic material is tape, the thermal conductivity of which is equal to or greater than that of the thermal compound provided between the base plate and the cooling body. Furthermore, to solve the above problems, there is provided a semiconductor device comprising: a base plate having a silicon carbide forming body and a metal filling body, the metal filling body having a through hole; a semiconductor element mounted on the upper surface of the base plate via an insulating substrate; a protective member formed on the surface of the metal filling body and having a hardness lower than that of the silicon carbide forming body; and a cooling body attached to the bottom side of the base plate and fastened to the base plate by screws passing through the through holes, the protective member being formed on a first surface of the metal filling body located on the upper surface side of the silicon carbide forming body to flatten the upper surface of the silicon carbide forming body and the upper surface of the protective member; and a second surface of the metal filling body located on the lower surface side of the silicon carbide forming body to flatten the lower surface of the silicon carbide forming body and the lower surface of the protective member, the protective member having an elastic modulus that flattens the lower surface of the silicon carbide forming body and the lower surface of the protective member when the base plate and the cooling body are fastened together. Also, to solve the above-mentioned problems, a semiconductor device is provided, comprising: a base plate having a silicon carbide forming body and a metal filling body, the metal filling body having a through hole, a semiconductor element mounted on the upper surface of the base plate via an insulating substrate, a protective member formed on the surface of the metal filling body and having a hardness lower than that of the silicon carbide forming body, and a cooling body attached to the bottom side of the base plate and fastened to the base plate by screws passing through the through hole, the protective member formed on the surface of the metal filling body located on the lower surface side of the silicon carbide forming body to flatten the lower surface of the silicon carbide forming body and the protective member, the protective member having an elastic modulus that flattens the lower surface of the silicon carbide forming body and the lower surface of the protective member when the base plate and the cooling body are fastened together. Furthermore, to solve the above-mentioned problems, a method for manufacturing a semiconductor device is provided, which comprises: sintering silicon carbide in a location avoiding a predetermined region; molding a base plate having the sintered silicon carbide and a silicon carbide formed body by pouring a melt of a metal composite material into the predetermined region; and forming a metal filler by filling the predetermined region with the melt of the metal composite material; machining the metal filler to form a through hole; forming a protective member on a surface of the metal filler having a hardness lower than that of the silicon carbide formed body; mounting a semiconductor element on the top surface of the base plate via an insulating substrate; and forming a protective member on the bottom surface of the base plate. The cooling body is fastened to the base plate by screws that are attached to the side and passed through the through holes, and the protective member is formed on a first surface of the metal filler located on the upper surface side of the silicon carbide forming body to flatten the upper surface of the silicon carbide forming body and the upper surface of the protective member, and is formed on a second surface of the metal filler located on the lower surface side of the silicon carbide forming body to flatten the lower surface of the silicon carbide forming body and the lower surface of the protective member, and the protective member has an elastic modulus that flatten the lower surface of the silicon carbide forming body and the lower surface of the protective member when the base plate and the cooling body are fastened. Furthermore, to solve the above-mentioned problems, a method for manufacturing a semiconductor device is provided, which includes sintering silicon carbide in a location avoiding a predetermined region, molding a silicon carbide formed body by combining the sintered silicon carbide with the sintered silicon carbide and pouring a melt of a metal composite material into the predetermined region, and forming a metal filler by filling the predetermined region with the melt of the metal composite material, cutting the metal filler to form a through hole, forming a protective member on a surface of the metal filler having a hardness lower than that of the silicon carbide formed body, mounting a semiconductor device on the upper surface of the base plate via an insulating substrate, fastening a cooling body to the base plate with screws attached to the bottom side of the base plate and passing through the through hole, the protective member being formed on the surface of the metal filler located on the lower surface side of the silicon carbide formed body to flatten the lower surface of the silicon carbide formed body and the protective member, and the protective member having an elastic modulus that flattens the lower surface of the silicon carbide formed body and the protective member when the base plate and the cooling body are fastened together. [Effects of the Invention]

[0009] According to one aspect, it is possible to suppress the generation of unnecessary stress on each member constituting the device. The above and other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings illustrating preferred embodiments of the present invention. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing an example of the configuration of a semiconductor device of the present invention; [Figure 2] 1A and 1B are diagrams illustrating a state in which the silicon carbide forming body and the metal filler are flat, in which (a) is a plan view of the heat dissipating base plate during the manufacturing process, and (b) is a view of the heat dissipating base plate during the manufacturing process as seen from direction A. [Figure 3] 1A and 1B are diagrams illustrating a state in which a step occurs between a silicon carbide forming body and a metal filler, in which (a) is a plan view of a heat dissipating base plate during the manufacturing process, and (b) is a view of the heat dissipating base plate during the manufacturing process as seen from direction A. [Figure 4] FIG. 10 is a diagram for explaining the generation of stress. [Figure 5] 10A to 10C are diagrams illustrating a manufacturing process of the base plate. [Figure 6] 1A and 1B are diagrams for explaining the manufacturing process of the base plate, in which (a) is a plan view of the base plate in the manufacturing process, and (b) is a view of the base plate in the manufacturing process as seen from direction A. [Figure 7] 1A and 1B are diagrams for explaining the manufacturing process of the base plate, in which (a) is a plan view of the base plate in the manufacturing process, and (b) is a view of the base plate in the manufacturing process as seen from direction A. [Figure 8] 1A and 1B are diagrams for explaining the manufacturing process of the base plate, in which (a) is a plan view of the base plate in the manufacturing process, and (b) is a view of the base plate in the manufacturing process as seen from direction A. [Figure 9] FIG. 10 is a diagram for explaining the thickness of a step. [Figure 10] FIG. 10 is a diagram for explaining suppression of stress generation. [Figure 11] 10A and 10B are diagrams showing modified examples of the configuration of the semiconductor device of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, the present embodiment will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functions may be designated by the same reference numerals to avoid redundant description. In the following description, the "upper surface" refers to the surface facing upward as viewed from the paper surface. Similarly, "upper" and "upper part" refer to the direction facing upward as viewed from the paper surface. The "lower surface" refers to the surface facing downward as viewed from the paper surface. under Similarly, "downward" refers to a direction facing downward as viewed from the plane of the paper. This directionality is used in all drawings. "Top", "upper", "upper part", "bottom", and "downward" are merely convenient expressions for specifying relative positional relationships and do not limit the technical concept of the present invention.

[0012] <Configuration of semiconductor device> FIG. 1 is a diagram showing an example of the configuration of a semiconductor device of the present invention. It shows a cross-sectional view of a semiconductor device 10. Dashed lineB1-B2 indicates a cross-sectional line of the semiconductor device 10 shown in Figure 1. The semiconductor device 10 includes an insulating substrate 12 and a semiconductor element 1 mounted on a cooling body 3 via a base plate 2.

[0013] The insulating substrate 12 has an insulating plate 12a and patterns (foils) 12b, 12c-1, and 12c-2 (hereinafter, patterns 12c-1 and 12c-2 will be collectively referred to as pattern 12c.) If patterns 12b and 12c are copper patterns, for example, a DCB (Direct Copper Bonding) substrate can be used in which patterns 12b and 12c are directly bonded to insulating plate 12a.

[0014] The insulating plate 12a is made of, for example, alumina ( Al 2 O 3), aluminum nitride (AlN), silicon nitride ( Si 3 N 4), a resin material such as epoxy, or an insulating material such as an epoxy resin material using a ceramic material as a filler.

[0015] One surface of a base plate 2 is mounted on the top surface of the cooling body 3, and an insulating substrate 12 is mounted on the other surface of the base plate 2. Then, a pattern 12b of the insulating substrate 12 is joined to the base plate 2 via a joining material 13a (solder or the like). A thermal compound (not shown) is provided between the base plate 2 and the top surface of the cooling body 3.

[0016] For example, a semiconductor element 1 made of silicon is bonded via a bonding material 13b (such as solder) onto the pattern 12c-1 of the insulating substrate 12. On the other hand, the wire 14 is, for example, an aluminum wire with a wire diameter of 300 μm to 400 μm.

[0017] Wire 14 joins the electrode of semiconductor element 1 to pattern 12c-2, which serves as a lead electrode of insulating substrate 12. Note that, for example, an electrode (Al-Si electrode) coated with an Al-Si alloy film is formed on semiconductor element 1. Wire bonding using ultrasonic waves and load is performed for joining with wire 14. Furthermore, external terminal 16a provided on case 16 is joined to pattern 12c-1, and external terminal 16b provided on case 16 is joined to pattern 12c-2.

[0018] The insulating substrate 12 to which the semiconductor element 1 is bonded is housed in a case 16, and the area surrounded by the case 16 and the base plate 2 is filled with a sealing resin 15 for sealing. Here, the patterns 12b and 12c of the insulating substrate 12 are made of a material with excellent conductivity. Such a material may be, for example, copper, aluminum, or an alloy containing at least one of these. The thickness of the patterns 12b and 12c is preferably 0.10 mm or more and 2.00 mm or less, and more preferably 0.20 mm or more and 1.00 mm or less.

[0019] In addition to the semiconductor element 1, wiring members and electronic components such as bonding wires, lead frames, and connection terminals can be appropriately arranged on the pattern 12c as needed. Such pattern 12c can also be plated with a material with excellent corrosion resistance. Examples of such materials include aluminum, nickel, titanium, chromium, molybdenum, tantalum, niobium, tungsten, vanadium, bismuth, zirconium, hafnium, gold, silver, platinum, palladium, and alloys containing at least one of these metals. The number, arrangement, and shape of the pattern 12c can be selected appropriately depending on the design.

[0020] Base plate 2 is a heat dissipating base plate and includes silicon carbide forming body 2a, metal fillers 2b1 and 2b2, and metal fillers 2b3 to 2b6 (not shown), and pattern 12b of insulating substrate 12 is bonded to the upper surface of silicon carbide forming body 2a with bonding material 13a. Silicon carbide forming body 2a is thicker than metal fillers 2b1 and 2b2.

[0021] Furthermore, protective members pr1a, pr1b, pr2a, and pr2b are formed on the surfaces of metal fillers 2b1 and 2b2. That is, protective members pr1a and pr2a are formed on the surfaces (first surfaces) of metal fillers 2b1 and 2b2 located on the upper surface side of silicon carbide forming body 2a, thereby flattening the upper surface of silicon carbide forming body 2a and the upper surfaces of protective members pr1a and pr2a.

[0022] Protective members pr1b and pr2b are formed on the surfaces (second surfaces) of metal fillers 2b1 and 2b2 located on the lower surface side of silicon carbide forming body 2a, thereby flattening the lower surface of silicon carbide forming body 2a and the lower surfaces of protective members pr1b and pr2b. Meanwhile, cooling body 3 is fastened to the bottom side of base plate 2 by screws sc1 and sc2 that pass through through holes provided in metal fillers 2b1 and 2b2.

[0023] Here, the silicon carbide forming body 2a of the base plate 2 is formed from silicon carbide and a metal composite material. The metal composite material is made of a metal with excellent thermal conductivity. Such a metal is, for example, aluminum, magnesium, or an alloy containing at least one of these. The silicon carbide forming body 2a may also be aluminum-silicon nitride (AlSiC), magnesium-silicon nitride (MgSiC), or the like.

[0024] The material of the metal fillers 2b1 and 2b2 is, for example, Mg, Al, or an alloy containing at least one of these. The protective members pr1a, pr1b, pr2a, and pr2b are metal plates or elastic materials, and have a lower hardness than the silicon carbide forming body 2a. The material of the metal plates is either Cu, Al, or Fe, and the elastic material is, for example, tape. The thermal conductivity of the tape is preferably equal to or higher than the thermal conductivity of the thermal compound provided between the base plate 2 and the upper surface of the cooling body 3. The tape is preferably, for example, a tape with an adhesive attached to a metal foil such as copper foil or aluminum foil, or a tape with an adhesive attached to a resin such as polyimide. The hardness is, for example, Vickers hardness.

[0025] Meanwhile, the total thickness of the protective member pr1a (first protective member) and the protective member pr1b (second protective member) is 1.2% to 2% of the thickness of the silicon carbide forming body 2a. Similarly, the total thickness of the protective member pr2a (first protective member) and the protective member pr2b (second protective member) is 1.2% to 2% of the thickness of the silicon carbide forming body 2a. In addition, the areas of the protective members pr1a, pr1b, pr2a, and pr2b are each , metal filling body 2b1, 2b2 the top or bottom of is equal to the area covered by

[0026] The protective member pr1b has an elastic modulus that flattens the lower surface of the silicon carbide forming body 2a and the lower surface of the protective member pr1b when the base plate 2 and the cooling body 3 are fastened together with the screw SC1. Similarly, the protective member pr2b has an elastic modulus that flattens the lower surface of the silicon carbide forming body 2a and the lower surface of the protective member pr2b when the base plate 2 and the cooling body 3 are fastened together with the screw SC2.

[0027] To improve corrosion resistance, a material such as nickel may be formed on the surface of the base plate 2 by plating. Specific examples of such materials include nickel-phosphorus alloys and nickel-boron alloys, in addition to nickel. The thickness of the plating film is preferably 1 μm or more, and more preferably 5 μm or more. The cooling body 3 is a heat sink with one or more fins, a water-cooled cooling device, or the like.

[0028] On the other hand, the semiconductor element 1 is a power device made of silicon, silicon carbide, or gallium nitride. The semiconductor element 1 includes a switching element. The switching element is a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), or the like.

[0029] Such a semiconductor element 1 includes, for example, a drain electrode (positive electrode, collector electrode in an IGBT) as a main electrode, and a gate electrode and a source electrode (negative electrode, emitter electrode in an IGBT) as control electrodes.

[0030] The semiconductor device 1 also includes a diode element, which may be, for example, a Schottky Barrier Diode (SBD) or a Free Wheeling Diode (FWD) such as a P-intrinsic-N (PiN) diode.

[0031] The thickness of the semiconductor element 1 is, for example, 80 μm or more and 500 μm or less, with an average thickness of about 200 μm. Other electronic components may also be disposed on the pattern 12c as needed. Examples of electronic components include capacitors, resistors, thermistors, current sensors, and control ICs (Integrated Circuits).

[0032] On the other hand, the case 16 is formed using a resin. Such a resin is mainly composed of a thermoplastic resin. Examples of the thermoplastic resin include polyphenylene sulfide resin, polybutylene terephthalate resin, polybutylene succinate resin, polyamide resin, and acrylonitrile butadiene styrene resin. The sealing resin 15 is, for example, a silicone gel.

[0033] <Stress caused by steps> Before describing the details of the present invention, the stress caused by the step between the silicon carbide forming body and the metal filler will be described with reference to Figures 2 to 4. Figures 2 and 3 are diagrams for explaining the state in which a step occurs between the silicon carbide forming body and the metal filler. In both Figures 2 and 3, (a) is a plan view of the heat dissipating base plate during the manufacturing process, and (b) is a view of the heat dissipating base plate during the manufacturing process as viewed from direction A.

[0034] 2, the metal of metal fillers 2b1-2b6 formed by filling a molten metal composite material into predetermined regions of silicon carbide body 2a is in a molten state. At this time, there is no step between the surface of silicon carbide body 2a and the surfaces of metal fillers 2b1-2b6, and the surfaces of silicon carbide body 2a and metal fillers 2b1-2b6 are flat.

[0035] 3, the melt of the metal composite material filled in a predetermined region of silicon carbide forming body 2a solidifies, and through holes h1-h6 are formed in metal fillers 2b1-2b6 after the metal has solidified. When the metal solidifies, a step d0a occurs between the upper surface of silicon carbide forming body 2a and the upper surfaces of metal fillers 2b1-2b6 due to the difference in linear expansion coefficients between silicon carbide forming body 2a and metal fillers 2b1-2b6. In addition, a step d0b occurs between the lower surface of silicon carbide forming body 2a and the lower surfaces of metal fillers 2b1-2b6.

[0036] 4 is a diagram illustrating the generation of stress. A conventional power semiconductor module 100 includes a heat dissipating base plate 200, an insulating substrate 12, a semiconductor element 1, and a cooling body 3. The heat dissipating base plate 200 has a silicon carbide forming body 2a and a metal filler 2b1, and the semiconductor element 1 is mounted on the upper surface of the silicon carbide forming body 2a via the insulating substrate 12.

[0037] The cooling body 3 is attached to the bottom surface of the heat dissipating base plate 200. In this case, the cooling body 3 is fastened to the heat dissipating base plate 200 by screws sc1 that pass through through holes provided in the metal filler 2b1.

[0038] As described above, steps d0a and d0b are formed between silicon carbide forming body 2a and metal filler 2b1. Therefore, when heat dissipating base plate 200 and cooling body 3 are fastened with screw sc1, unnecessary stress is generated due to the principle of leverage.

[0039] That is, the boundary n1 between the silicon carbide forming body 2a and the metal filler 2b1 where the step d0b occurs is the fulcrum, the part n2 where the axial force Pw of the screw sc1 is applied is the force point, and the mounting part n3 of the semiconductor element 1 is the point of action, and unnecessary stress is applied to each component of the power semiconductor module 100.

[0040] If such stress is applied, for example, distortion may occur in the metal filler 2b1, creating a risk of torque loss in the screw sc1, or the stress St concentrated at the point of application may cause damage or deterioration to the insulating substrate 12 or the semiconductor element 1.

[0041] <Base plate manufacturing process> 5 to 8 are diagrams for explaining the manufacturing process of the base plate. 6 8, (a) is a plan view of the base plate in the manufacturing process, and (b) is a view of the base plate in the manufacturing process as seen from direction A. Note that the dotted line B1-B2 in FIG. 8 indicates the cross-sectional line of the cross-sectional view of the semiconductor device 1 shown in FIG.

[0042] [Step P1] As shown in FIG. 5, silicon carbide 2a-1 is fired in a location avoiding the periphery of the through-hole. [Step P2] As shown in FIG. 6, the sintered silicon carbide 2a-1 and predetermined regions are filled with a melt of a metal composite to form metal fillers 2b1 to 2b6.

[0043] For example, the metal fillers 2b1 to 2b6 are provided in the peripheral frame portion (corresponding to the metal fillers 2b3 and 2b6 in the example of FIG. 6) or the corner portions (corresponding to the metal fillers 2b1, 2b2, 2b4, and 2b5 in the example of FIG. 6) of the manufactured base plate 2. Note that the predetermined region is, for example, the peripheral region where the through holes h1 to h6 of the base plate 2 are provided.

[0044] In step P2, the metal filling bodies 2b1 to 2b6 are in a state before solidification, and therefore the silicon carbide forming bodies 2a The face and metal fillers 2b1 to 2b6 The face There is no step between the silicon carbide forming body 2a The face and metal fillers 2b1 to 2b6 The face and is flat.

[0045] [Step P3] As shown in FIG. 7, the metal fillers 2b1 to 2b6 are solidified, and through-holes h1 to h6 are formed in the metal fillers 2b1 to 2b6, respectively, by cutting such as punching.

[0046] When the metal fillers 2b1 to 2b6 solidify, The metal of the silicon carbide former 2a and Due to the difference in the linear expansion coefficient of the metals of metal fillers 2b1-2b6, metal fillers 2b1-2b6 are thinner than silicon carbide formation 2a, and steps d0a, d0b are generated between silicon carbide formation 2a and metal fillers 2b1-2b6.

[0047] In FIG. 7(b), the upper surface of the silicon carbide forming body 2a and the metal filling bodies 2b1, 2b3, and 2b Top of 2 and between the lower surface of the silicon carbide forming body 2a and the metal filling bodies 2b1, 2b3, 2b Bottom of 2 10, steps d0a and d0b are generated between the two.

[0048] [Step P4] Protective members are formed on the surfaces of the metal fillings 2b1-2b6 where the steps d0a, d0b are formed, as shown in Fig. 8. The protective members are formed so as to cover at least the peripheries of the through holes h1-h6. 8(b), a protective member pr1a is formed on the surface of the metal filler 2b1 where a step d0a occurs relative to the upper surface of the silicon carbide forming body 2a, and a protective member pr1b is formed on the surface of the metal filler 2b1 where a step d0b occurs relative to the lower surface of the silicon carbide forming body 2a. As a result, the upper surface of the silicon carbide forming body 2a and the upper surface of the protective member pr1a are flattened, and the lower surface of the silicon carbide forming body 2a and the lower surface of the protective member pr1b are flattened.

[0049] Furthermore, a protective member pr2a is formed on the surface of the metal filler 2b2 where a step d0a occurs relative to the upper surface of the silicon carbide forming body 2a, and a protective member pr2b is formed on the surface of the metal filler 2b2 where a step d0b occurs relative to the lower surface of the silicon carbide forming body 2a. As a result, the upper surface of the silicon carbide forming body 2a and the upper surface of the protective member pr2a are flattened, and the lower surface of the silicon carbide forming body 2a and the lower surface of the protective member pr2b are flattened.

[0050] Furthermore, a protective member pr3a is formed on the surface of the metal filler 2b3 where a step d0a occurs relative to the upper surface of the silicon carbide forming body 2a, and a protective member pr3b is formed on the surface of the metal filler 2b3 where a step d0b occurs relative to the lower surface of the silicon carbide forming body 2a. As a result, the upper surface of the silicon carbide forming body 2a and the upper surface of the protective member pr3a are flattened, and the lower surface of the silicon carbide forming body 2a and the lower surface of the protective member pr3b are flattened. Protective members are also formed in the same manner on the surfaces of the metal fillers 2b4 to 2b6 where steps occur.

[0051] <Step thickness> 9 is a diagram illustrating the thickness of the step. The sum of the step d0a and step d0b caused by the calculated difference in linear expansion coefficient is step d0a+step d0b=68-82 μm when the thickness of silicon carbide forming body 2a is 5 mm and the material of metal fillers 2b1-2b6 is MgSiC. In other words, the sum of step d0a and step d0b is 1.2-2% of the thickness of silicon carbide forming body 2a.

[0052] Furthermore, when the thickness of the silicon carbide forming body 2a is 5 mm and the material of the metal fillers 2b1 to 2b6 is AlSiC, the step difference d0a+step difference d0b=63 to 77 μm. When the thickness of the silicon carbide forming body 2a is doubled, the step difference d0a+step difference d0b becomes twice the value described above. In other words, the total value of the step differences d0a and d0b is 1.2 to 2% of the thickness of the silicon carbide forming body 2a. Note that the metal filler 2b1 solidifies and becomes the thickness of the silicon carbide forming body 2a. Side wall Plate thickness direction Center of DepartmentHowever, as shown by the arrow ar, the step may be formed closer to the upper surface side or the lower surface side of the silicon carbide forming body 2a (the total value of the step does not change).

[0053] <Stress suppression> 10 is a diagram illustrating the suppression of stress generation. Semiconductor device 10 includes base plate 2, insulating substrate 12, semiconductor element 1, cooling body 3, and protective members pr1a and pr1b. Base plate 2 has silicon carbide forming body 2a and metal filler 2b1, and semiconductor element 1 is mounted on the upper surface of silicon carbide forming body 2a via insulating substrate 12.

[0054] The cooling body 3 is attached to the bottom surface side of the base plate 2. In this case, the cooling body 3 is fastened to the base plate 2 by a screw sc1 that passes through a through-hole provided in the metal filler 2b1.

[0055] In the semiconductor device 10 of the present invention, as described above, a protective member pr1a is formed on the surface of the metal filler 2b1 where a step d0a was formed relative to the upper surface of the silicon carbide forming body 2a, and a protective member pr1b is formed on the surface of the metal filler 2b1 where a step d0b was formed relative to the lower surface of the silicon carbide forming body 2a. The upper surface of the silicon carbide forming body 2a and the upper surface of the protective member pr2a are then flattened, and the lower surface of the silicon carbide forming body 2a and the lower surface of the protective member pr2b are also flattened. The protective members pr1a and pr1b may be provided such that the total thickness of the protective members pr1a and pr1b is 1.2 to 2% of the thickness of the silicon carbide forming body 2a. In this case, the sum of the steps d0a and d0b is 1.2 to 2% of the thickness of the silicon carbide forming body 2a, so that the upper surface of the silicon carbide forming body 2a and the upper surface of the protective member pr2a are preferably flattened, and the lower surface of the silicon carbide forming body 2a and the lower surface of the protective member pr2b are preferably flattened.

[0056] This configuration eliminates the steps d0a and d0b, so even if the axial force Pw of the screw sc1 is applied to the base plate 2 and the cooling body 3, no fulcrum of the principle of leverage is generated. This makes it possible to suppress the generation of unnecessary stress on each component of the semiconductor device 10. Therefore, the axial force Pw generated by fastening the screw sc1 does not cause distortion in the metal filler 2b1, preventing torque loss of the screw sc1. This also prevents damage and deterioration of the insulating substrate 12 and the semiconductor element 1. Note that the protective members pr1a, pr1b, pr2a, and pr2b only need to be formed to cover at least the periphery of the through hole. Even in such cases, it is possible to suppress the generation of a fulcrum of the principle of leverage and suppress the generation of unnecessary stress on each component of the semiconductor device 10.

[0057] Figure 11 shows a modified example of the configuration of a semiconductor device of the present invention. Semiconductor device 10-1 includes a base plate 2, an insulating substrate 12, a semiconductor element 1, a cooling body 3, and a protective member pr1b. The difference from the configuration shown in Figure 10 is that no protective member pr1a is formed for the step d0a that occurs on the side where insulating substrate 12 is mounted.

[0058] That is, in the semiconductor device 10-1 of the present invention, the protective member pr1b is formed on the surface of the metal filling member 2b1 where the step d0b was generated with respect to the lower surface of the silicon carbide forming body 2a. pr1b The protective member pr1b has an elastic modulus that allows the lower surface of the silicon carbide forming body 2a and the lower surface of the protective member pr1b to be flattened together when the base plate 2 and the cooling body 3 are fastened together with the screw sc1.

[0059] In this way, even with the configuration in which the protective member pr1b is formed only on the surface of the metal filler 2b1 located on the lower surface side of the silicon carbide forming body 2a, it is possible to suppress the generation of unnecessary stress due to the axial force Pw of the fastening of the screw sc1.

[0060] As described above, according to the present invention, a base plate has a silicon carbide forming body and a metal filling body, and a through hole is provided in the metal filling body, and a protective member having a hardness lower than that of the silicon carbide forming body is formed on the surface of the metal filling body.

[0061] This makes it possible to suppress the generation of unnecessary stress on the components that make up the device. This allows the tightening torque of the screws to be increased and also prevents torque loss due to distortion of the metal filler. Furthermore, because unnecessary stress is not applied to the product, the occurrence of product failure can be suppressed.

[0062] Although the embodiments have been described above, the configuration of each part shown in the embodiments can be replaced with other parts having similar functions. Also, any other components or processes may be added. Furthermore, any two or more configurations (features) of the above-described embodiments may be combined. The foregoing merely illustrates the principles of the present invention. Further, since numerous modifications and changes will be apparent to those skilled in the art, the present invention is not limited to the exact construction and application shown and described above, and all corresponding modifications and equivalents are deemed to be within the scope of the present invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0063] 1. Semiconductor element 2 base plate 2a-1 Silicon carbide 2a Silicon carbide former 2b1~2b6 Metal filling h1~h6 through hole pr1a~pr6a, pr1b~pr3b protective members 3 Cooling body 10, 10-1 Semiconductor device 12 Insulating substrate 12a Insulating plate 12b, 12c-1, 12c-2 patterns 13a, 13b Bonding material 14 wire 15 Sealing resin 16 cases 16a, 16b external terminal s c1, sc2 screws P1~P4 process Pw Axial force 100 Power Semiconductor Module 200 Heat dissipation base plate n1 Fulcrum point n2 Emphasis points n3 Point of action St Stress concentrated at the point of application d0a step d0b step ar Direction in which the metal filler moves

Claims

1. a base plate having a silicon carbide forming body and a metal filling body, the metal filling body having a through hole; a semiconductor element mounted on an upper surface of the base plate via an insulating substrate; a protective member formed on a surface of the metal filler and having a hardness lower than that of the silicon carbide body; a cooling body attached to a bottom surface side of the base plate and fastened to the base plate by a screw inserted through the through hole, The protective member is a metal plate or an elastic material, the metal plate is made of any one of Cu, Al, and Fe; the elastic material is a tape, and the thermal conductivity of the tape is equal to or higher than that of a thermal compound provided between the base plate and the cooling body; Semiconductor device.

2. The protective member is a first surface of the metal filler located on the upper surface side of the silicon carbide body, to flatten the upper surface of the silicon carbide body and the upper surface of the protective member; a second surface of the metal filler located on the lower surface side of the silicon carbide body, thereby flattening the lower surface of the silicon carbide body and the lower surface of the protective member; The semiconductor device according to claim 1.

3. 2. The semiconductor device according to claim 1, wherein the protective member is formed on a surface of the metal filler located on a lower surface side of the silicon carbide forming body, thereby flattening the lower surface of the silicon carbide forming body and the lower surface of the protective member.

4. 2. The semiconductor device according to claim 1, wherein said silicon carbide body is made of MgSiC or AlSiC.

5. 2. The semiconductor device according to claim 1, wherein said metal filling material is Mg or Al.

6. 4. The semiconductor device according to claim 2, wherein the protective member has an elastic modulus that flattens a lower surface of the silicon carbide body and a lower surface of the protective member when the base plate and the cooling body are fastened together.

7. The semiconductor device of claim 1, wherein the sum of the thicknesses of the first protective member formed on the first surface of the metal filler located on the upper surface side of the silicon carbide forming body and the second protective member formed on the second surface of the metal filler located on the lower surface side of the silicon carbide forming body is 1.2% to 2% of the thickness of the silicon carbide forming body.

8. 2. The semiconductor device according to claim 1, wherein the area of ​​said protective member is equal to the area covering the upper or lower surface of said metal filling body.

9. The semiconductor device of claim 1 , wherein the thickness of said silicon carbide body is greater than the thickness of said metal filling body.

10. 2. The semiconductor device according to claim 1, wherein said metal filling is provided on a peripheral frame portion of said base plate or on a corner portion of said base plate.

11. The semiconductor device according to claim 1 , wherein said protective member covers at least the periphery of said through hole.

12. A base plate is molded having a silicon carbide formed body obtained by sintering silicon carbide in a location avoiding a predetermined region and injecting a melt of a metal composite material into the sintered silicon carbide and the predetermined region, and a metal filler formed by filling the melt of the metal composite material into the predetermined region; A through hole is formed by cutting the metal filler. forming a protective member on a surface of the metal filler, the protective member having a hardness lower than that of the silicon carbide body; a semiconductor element is mounted on the upper surface of the base plate via an insulating substrate; a cooling body is fastened to the base plate by a screw attached to a bottom surface of the base plate and passed through the through hole; The protective member is a metal plate or an elastic material, the metal plate is made of any one of Cu, Al, and Fe; the elastic material is a tape, and the thermal conductivity of the tape is equal to or higher than that of a thermal compound provided between the base plate and the cooling body; A method for manufacturing a semiconductor device.

13. A method for manufacturing a silicon carbide substrate, comprising: forming a silicon carbide body and a metal filler, the metal filler having a through hole; a semiconductor element mounted on an upper surface of the base plate via an insulating substrate; a protective member formed on a surface of the metal filler and having a hardness lower than that of the silicon carbide body; a cooling body attached to a bottom surface side of the base plate and fastened to the base plate by a screw inserted through the through hole, The protective member is a first surface of the metal filler located on the upper surface side of the silicon carbide body, to flatten the upper surface of the silicon carbide body and the upper surface of the protective member; a second surface of the metal filler located on the lower surface side of the silicon carbide body, to flatten the lower surface of the silicon carbide body and the lower surface of the protective member; the protective member has an elastic modulus that flattens a lower surface of the silicon carbide body and a lower surface of the protective member when the base plate and the cooling body are fastened together. Semiconductor device.

14. A method for manufacturing a silicon carbide substrate, comprising: forming a silicon carbide body and a metal filler, the metal filler having a through hole; a semiconductor element mounted on an upper surface of the base plate via an insulating substrate; a protective member formed on a surface of the metal filler and having a hardness lower than that of the silicon carbide body; a cooling body attached to a bottom surface side of the base plate and fastened to the base plate by a screw inserted through the through hole, the protective member is formed on a surface of the metal filler located on a lower surface side of the silicon carbide body, and flattens the lower surface of the silicon carbide body and the lower surface of the protective member; the protective member has an elastic modulus that flattens a lower surface of the silicon carbide body and a lower surface of the protective member when the base plate and the cooling body are fastened together. Semiconductor device.

15. A base plate is molded having a silicon carbide formed body obtained by sintering silicon carbide in a location avoiding a predetermined area and pouring a melt of a metal composite material into the sintered silicon carbide and the predetermined area, and a metal filler formed by filling the melt of the metal composite material into the predetermined area, A through hole is formed by cutting the metal filler. forming a protective member on a surface of the metal filler, the protective member having a hardness lower than that of the silicon carbide body; a semiconductor element is mounted on the upper surface of the base plate via an insulating substrate; a cooling body is fastened to the base plate by a screw attached to a bottom surface of the base plate and passed through the through hole; The protective member is a first surface of the metal filler located on the upper surface side of the silicon carbide body, to flatten the upper surface of the silicon carbide body and the upper surface of the protective member; a second surface of the metal filler located on the lower surface side of the silicon carbide body, to flatten the lower surface of the silicon carbide body and the lower surface of the protective member; the protective member has an elastic modulus that flattens a lower surface of the silicon carbide body and a lower surface of the protective member when the base plate and the cooling body are fastened together. A method for manufacturing a semiconductor device.

16. A base plate is molded having a silicon carbide formed body obtained by sintering silicon carbide in a location avoiding a predetermined area and pouring a melt of a metal composite material into the sintered silicon carbide and the predetermined area, and a metal filler formed by filling the melt of the metal composite material into the predetermined area, A through hole is formed by cutting the metal filler. forming a protective member on a surface of the metal filler, the protective member having a hardness lower than that of the silicon carbide body; a semiconductor element is mounted on the upper surface of the base plate via an insulating substrate; a cooling body is fastened to the base plate by a screw attached to a bottom surface of the base plate and passed through the through hole; the protective member is formed on a surface of the metal filler located on a lower surface side of the silicon carbide body, and flattens the lower surface of the silicon carbide body and the lower surface of the protective member; the protective member has an elastic modulus that flattens a lower surface of the silicon carbide body and a lower surface of the protective member when the base plate and the cooling body are fastened together. A method for manufacturing a semiconductor device.

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