Multilayer bonded body, semiconductor device using same, and method for manufacturing same

Abstract

When a multilayer bonded body is formed such as when a heat sink is bonded to an insulating circuit board, the heat sink and the insulating circuit board are bonded at a low temperature to suppress warpage. A multilayer bonded body is provided with: a ceramic substrate; a first aluminum plate bonded to one surface of the ceramic substrate and including aluminum or an aluminum alloy; a first intermediate metal layer that is bonded to the surface of the first aluminum plate on the opposite side from the ceramic substrate and contains any one of copper, nickel, silver and gold; a first copper sintered layer bonded to a surface of the first intermediate metal layer on the opposite side from the first aluminum plate; and a first metal member that is bonded to the surface of the first copper sintered layer on the opposite side from the first intermediate metal layer, and contains any one of aluminum, an aluminum alloy, copper, and a copper alloy.

Description

Technical Field

[0001] The present invention relates to a multilayer joint body and a semiconductor device using the multilayer joint body, as well as a method for manufacturing the multilayer joint body and the semiconductor device. The multilayer joint body can be used as an insulating circuit substrate, and a metal component comprising any one of aluminum, aluminum alloy, copper and copper alloy is joined to an aluminum plate joined to a ceramic substrate by a copper bonding material. This application claims priority based on patent application No. 2022-114292 filed in Japan on July 15, 2022 and patent application No. 2023-110428 filed on July 5, 2023, and the contents thereof are cited herein. Background Art

[0002] On an insulating circuit board on which electronic components such as LEDs and power elements are mounted, a heat sink is provided for dissipating heat generated by the electronic components.

[0003] In this case, it is also known that a ceramic substrate is used as an insulating circuit substrate, a circuit layer is formed on one surface of the ceramic substrate serving as an insulating layer, and a heat dissipation layer is formed on the other surface of the ceramic substrate. A heat sink having excellent thermal conductivity is bonded to the heat dissipation layer via solder, and electronic components are mounted on the circuit layer via solder, thereby obtaining an insulating circuit substrate with a heat sink.

[0004] In such an insulating circuit board with a heat sink, an aluminum plate of the insulating circuit board and a heat sink are bonded to each other at a high temperature such as 600°C.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-35965

[0006] In the past, if the insulating circuit substrate and the heat sink were bonded at high temperature, warping would easily occur during the cooling process due to the thermal expansion difference between the ceramic substrate with a low thermal expansion coefficient and the heat sink. Therefore, it is desirable to bond the insulating circuit substrate and the heat sink at low temperature. Not limited to the heat sink, in the case of bonding the circuit layer with a copper plate or the like to an aluminum plate of the insulating circuit substrate, if the heating temperature is high, warping may occur during cooling due to the thermal expansion difference, and the bonding property may be reduced.

[0007] Patent Document 1 discloses a power module that uses an insulating circuit substrate in which copper plates are bonded to both surfaces of a ceramic substrate. In this power module, a heat dissipation substrate made of copper or the like is bonded to the copper plates of the insulating circuit substrate via a bonding material. In Patent Document 1, since copper plates are bonded to both surfaces of an insulating substrate made of ceramic, a large warpage may occur due to a difference in thermal expansion coefficient, thereby reducing bonding properties. Summary of the invention

[0008] Therefore, an object of the present invention is to improve bonding properties by bonding at low temperature to suppress warping when forming a multilayer bonded body, such as when bonding a heat sink to an insulating circuit substrate.

[0009] [Multi-layered bonded body]

[0010] The multilayer joint body of the present invention comprises: a ceramic substrate; a first aluminum plate joined to one surface of the ceramic substrate and comprising aluminum or an aluminum alloy; a first intermediate metal layer joined to the surface of the first aluminum plate on the opposite side to the ceramic substrate and comprising any one of copper, nickel, silver and gold; a first copper sintered layer joined to the surface of the first intermediate metal layer on the opposite side to the first aluminum plate; and a first metal component joined to the surface of the first copper sintered layer on the opposite side to the first intermediate metal layer and comprising any one of aluminum, an aluminum alloy, copper and a copper alloy.

[0011] In the multilayer bonded body of the present invention, the first metal member may include aluminum or an aluminum alloy, and a second intermediate metal layer including any one of copper, nickel, silver and gold may be formed between the first metal member and the first copper sintered layer.

[0012] In the multilayer bonded body of the present invention, a second aluminum plate made of aluminum or an aluminum alloy may be bonded to the other surface of the ceramic substrate.

[0013] The multilayer joint body of the present invention may further include: a third intermediate metal layer, which is joined to the surface of the second aluminum plate on the opposite side to the ceramic substrate and includes any one of copper, nickel, silver and gold; a second copper sintered layer, which is joined to the surface of the third intermediate metal layer on the opposite side to the second aluminum plate; and a second metal part, which is joined to the surface of the second copper sintered layer on the opposite side to the second aluminum plate and includes any one of aluminum, aluminum alloy, copper and copper alloy.

[0014] In the multilayer bonded body of the present invention, the second metal member may include aluminum or an aluminum alloy, and a fourth intermediate metal layer including any one of copper, nickel, silver and gold may be formed between the second metal member and the second copper sintered layer.

[0015] In the present invention, "a first metal component including any one of aluminum, aluminum alloy, copper and copper alloy" means that at least the bonding surface of the first copper sintered layer side of the first metal component is composed of any one of aluminum, aluminum alloy, copper and copper alloy, and the first metal component can be composed of, for example, a composite material or a laminated material. In addition, "a first metal component including any one of aluminum, aluminum alloy, copper and copper alloy" also includes the case where the first metal component is composed of any one of aluminum, aluminum alloy, copper and copper alloy.

[0016] In the multilayer joint body of the present invention, the first intermediate metal layer formed on the surface of the first aluminum plate is joined to the first metal part by providing a first copper sintered layer. The first copper sintered layer is a copper sintered layer formed by sintering copper particles. The first copper sintered layer may be a layer formed by sintering a copper paste, or a layer formed by sintering a joining sheet formed by connecting a plurality of copper particles with an adhesive to form a sheet, or a layer formed by sintering a copper sintered sheet formed by partially sintering copper particles to form a sheet.

[0017] The first copper sintered layer using the bonding sheet is a layer obtained by sintering a sheet-shaped first bonding material formed by connecting a plurality of copper particles with a bonding agent, but the amount of bonding agent is less than that of the first copper sintered layer using the copper paste, so that voids generated by the volatilization of organic components during sintering are suppressed, which is preferred. In addition, by providing the first intermediate metal layer, the bonding property between the first aluminum plate and the first copper sintered layer is good.

[0018] In the present invention, “a first intermediate metal layer including any one of copper, nickel, silver and gold” means that at least the bonding surface of the first copper sintered layer side of the first intermediate metal layer is composed of any one of copper, nickel, silver and gold, and the first intermediate metal layer may be composed of, for example, a plurality of plating layers. Furthermore, “a first intermediate metal layer including any one of copper, nickel, silver and gold” also includes the case where the first intermediate metal layer is composed of any one of copper, nickel, silver and gold.

[0019] The multilayer bonded body of the present invention preferably has a second intermediate metal layer formed between the first metal member and the first copper sintered layer. When the first metal member includes aluminum or an aluminum alloy, the second intermediate metal layer preferably includes any one of copper, nickel, silver and gold.

[0020] In the present invention, “a second intermediate metal layer including any one of copper, nickel, silver and gold” means that at least the bonding surface of the second intermediate metal layer on the first copper sintered layer side is composed of any one of copper, nickel, silver and gold, and the second intermediate metal layer may be composed of, for example, a plurality of plating layers. Furthermore, “a second intermediate metal layer including any one of copper, nickel, silver and gold” also includes the case where the second intermediate metal layer is composed of any one of copper, nickel, silver and gold.

[0021] When the first metal member includes copper or a copper alloy, the second intermediate metal layer preferably does not include nickel, but may include nickel.

[0022] In the present invention, the second intermediate metal layer containing nickel means that at least the bonding surface of the second intermediate layer on the first copper sintered layer side is composed of nickel, and the second intermediate metal layer can be composed of, for example, a plurality of plating layers, etc. Furthermore, the second intermediate metal layer containing nickel also includes the case where the second intermediate metal layer is composed of nickel.

[0023] The first intermediate metal layer can improve the bonding between the first aluminum plate and the first copper sintered layer. The second intermediate metal layer can improve the bonding between the first metal member and the first copper sintered layer.

[0024] In the multilayer bonded body of the present invention, it is preferred that the first aluminum plate and the second aluminum plate be made of aluminum having a purity of 99.99 mass % or more.

[0025] Since the first aluminum plate and the second aluminum plate are made of soft high-purity aluminum of 4N (purity 99.99 mass%) or more specified in JIS (Japanese Industrial Standards), the yield stress is low, so that high bonding reliability with the ceramic substrate can be maintained during temperature cycles, and high thermal conductivity or high electrical conductivity with the first metal component, etc. can be exerted. There is no upper limit to the purity of aluminum, and it can be 99.999 mass% aluminum or 99.9999 mass% so-called 6N aluminum.

[0026] In the multilayer bonded body of the present invention, the size of the first aluminum plate, the first copper sintered layer, and the first metal component, in other words, the size of the bonding surface of the first aluminum plate, the first copper sintered layer, and the first metal component is not limited, but is preferably 100 mm. 2 Above and 10000mm 2 the following.

[0027] When the thickness of the first copper sintered layer in the lamination direction is 50 μm or more and 1000 μm or less, the first aluminum and the first metal member can be bonded well.

[0028] In the multilayer bonded body of the present invention, it is preferred that a plurality of grooves be formed on the surface of the first aluminum plate on the side opposite to the ceramic substrate.

[0029] By forming the groove on the surface of the first aluminum plate that is bonded to the first metal component, the volatilization of the adhesive during sintering becomes good, and the gap in the bonded portion can be reduced. Therefore, the bondability with the first metal component through the first copper sintered layer becomes good. In addition, by bonding, the groove portion after bonding can be smaller than before bonding.

[0030] The multilayer bonded body of the present invention can be provided as an insulating circuit substrate having the surface of the first metal member as the electronic component mounting surface.

[0031] When a multilayer joint body in which a second aluminum plate is joined to the surface of a ceramic substrate opposite to the first aluminum plate is used as an insulating circuit substrate, the surface of the first metal component can be used as the electronic component mounting surface, or the surface of the second aluminum plate can be used as the electronic component mounting surface.

[0032] In the insulating circuit substrate, the first aluminum plate and the second aluminum plate are made of soft high-purity aluminum of 4N or more, so that high bonding reliability with the ceramic substrate can be maintained during temperature cycles, and the insulating circuit substrate as a whole can exhibit high thermal conductivity or high electrical conductivity. There is no upper limit to the purity of aluminum, and it can be 99.999 mass% aluminum or 99.9999 mass% so-called 6N aluminum.

[0033] When the multilayer bonded body of the present invention is used as an insulating circuit substrate, the second aluminum plate can be used as a heat sink when the surface of the first metal member is used as an electronic component mounting surface. When the surface of the second aluminum plate is used as an electronic component mounting surface, the first metal member can be used as a heat sink.

[0034] [Semiconductor devices]

[0035] A semiconductor device can be constructed using the multilayer bonded body of the present invention.

[0036] The semiconductor device of the present invention comprises: an electronic component mounted on the surface of the first metal member on the side opposite to the first copper sintered layer; a lead frame connected to the electronic component; and an insulating resin that seals the electronic component in a state where the front end portion of the lead frame and at least the surface of the second aluminum plate on the side opposite to the ceramic substrate are exposed.

[0037] The semiconductor device of the present invention may include: an electronic component mounted on the surface of the second aluminum plate on the side opposite to the ceramic substrate; a lead frame connected to the electronic component; and an insulating resin that seals the electronic component in a state where the front end portion of the lead frame and at least the surface of the first metal component other than the bonding surface with the first copper sintered layer are exposed.

[0038] In a semiconductor device using a multilayer junction body provided with a second metal component, the device may include: an electronic component mounted on a surface of the first metal component on the side opposite to the first copper sintered layer; a lead frame connected to the electronic component; and an insulating resin that seals the electronic component in a state where a front end portion of the lead frame and a surface of the second metal component other than at least a junction surface with the second copper sintered layer are exposed.

[0039] [Method for producing a multilayered bonded body]

[0040] The manufacturing method of the multilayer joint body of the present invention comprises: a first lamination process, laminating a brazing material and a first aluminum plate containing aluminum or an aluminum alloy on one surface of a ceramic substrate to form a first lamination body; a first joining process, forming a first joint body by pressurizing and heating the first lamination body in a lamination state to join the first lamination body; an intermediate metal layer forming process, forming a first intermediate metal layer containing any one of copper, nickel, silver and gold on the surface of the first aluminum plate on the opposite side of the ceramic substrate in the first joint body; a second lamination process, laminating a first joining material formed into a sheet shape by connecting a plurality of copper particles with an adhesive and a first metal component containing any one of aluminum, aluminum alloy, copper and copper alloy in sequence on the first intermediate metal layer to form a second lamination body; and a second joining process, forming a first copper sintered layer by sintering the first joining material by heating the second lamination body in a state of pressurizing in a lamination direction, and joining the first intermediate metal layer in the first aluminum plate and the first metal component through the first copper sintered layer.

[0041] In the manufacturing method of the multilayer joint body of the present invention, the first metal part may include aluminum or an aluminum alloy. In the intermediate metal layer forming step, a second intermediate metal layer including any one of copper, nickel, silver and gold may be further formed on one surface of the first metal part. In the second bonding step, the second intermediate metal layer and the first copper sintered layer may be bonded.

[0042] By using the first bonding material to bond the first intermediate metal layer to the first metal component, voids generated by heating of the organic component during bonding can be suppressed, thereby improving bonding. In addition, the first bonding material formed into a sheet by connecting a plurality of copper particles with an adhesive can be a bonding material that is partially sintered when formed into a sheet.

[0043] In the method for producing a multilayer bonded body of the present invention, before the first lamination step, a plurality of grooves may be formed on a surface of the first aluminum plate on the side opposite to the ceramic substrate.

[0044] In the manufacturing method of the multilayer joint body of the present invention, in the first stacking step, the brazing material and the second aluminum plate containing aluminum or aluminum alloy are further stacked on the other surface of the ceramic substrate to form the first stacked body, and in the first joining step, the first stacked body containing the second aluminum plate is pressurized and heated to form the first joint body by joining the first aluminum plate to one surface of the ceramic substrate and joining the second aluminum plate to the other surface of the ceramic substrate.

[0045] In the manufacturing method of the multilayer joint body of the present invention, in the intermediate metal layer forming step, a third intermediate metal layer comprising any one of copper, nickel, silver and gold can be further formed on the surface of the second aluminum plate in the first joint body on the side opposite to the ceramic substrate; in the second stacking step, a second bonding material formed in a sheet shape by connecting a plurality of copper particles with an adhesive and a second metal component comprising any one of aluminum, aluminum alloy, copper and copper alloy are further stacked in sequence on the third intermediate metal layer; in the second bonding step, the second bonding material is further sintered to form a second copper sintered layer, and the third intermediate metal layer and the second metal component are bonded via the second copper sintered layer.

[0046] In the manufacturing method of the multilayer joint body of the present invention, the second metal part may include aluminum or an aluminum alloy. In the intermediate metal layer forming step, a fourth intermediate metal layer including any one of copper, nickel, silver and gold may be further formed on one surface of the second metal part. In the second bonding step, the surface of the fourth intermediate metal layer in the second metal part can be bonded to the second copper sintered layer.

[0047] [Method for manufacturing semiconductor device]

[0048] The present invention also provides a method for manufacturing a semiconductor device using the method for manufacturing the multilayer junction body.

[0049] The manufacturing method of a semiconductor device of the present invention uses the manufacturing method of the multilayer joint body to manufacture a semiconductor device, and the manufacturing method of a semiconductor device also includes, after the second joining process: a mounting process, mounting an electronic component on the first metal component and connecting a lead frame to the electronic component; and a resin sealing process, sealing the electronic component with the insulating resin in a state in which the front end portion of the lead frame and at least the surface of the second aluminum on the side opposite to the ceramic substrate are exposed from the insulating resin.

[0050] In the manufacturing method of the semiconductor device of the present invention, the following may be included between the intermediate layer forming process and the second stacking process: an installation process of mounting an electronic component on the second aluminum plate and connecting a lead frame to the electronic component; and a resin sealing process of sealing the electronic component with the insulating resin in a state where the front end portion of the lead frame and the surface of at least the first intermediate metal layer are exposed from the insulating resin.

[0051] In the method for manufacturing a semiconductor device of the present invention, in the intermediate layer forming step, a third intermediate metal layer including any one of copper, nickel, silver and gold can be further formed on the surface of the second aluminum plate in the first bonded body on the side opposite to the ceramic substrate, and the method for manufacturing a semiconductor device further includes, after the second bonding step: a mounting step of mounting an electronic component on the first metal component and connecting a lead frame to the electronic component; a resin sealing step of sealing the electronic component with an insulating resin in a state where the front end of the lead frame and at least the surface of the third intermediate metal layer are exposed from the insulating resin; a third lamination step of further laminating a second bonding material formed into a sheet shape by connecting a plurality of copper particles with an adhesive and a second metal component including any one of aluminum, aluminum alloy, copper and copper alloy on the third intermediate metal layer in sequence to form a third laminate; and a third bonding step of sintering the second bonding material to form a second copper sintered layer by heating the secondary laminate in a state where pressure is applied in the lamination direction, and bonding the third intermediate metal layer to the second metal component via the second copper sintered layer.

[0052] After the mounting step and the resin sealing step, a third bonding step involving pressurization and heating is performed. In this third bonding step, bonding is performed at a low temperature via the second copper sintered layer, so that thermal influences on electronic components, insulating resin, etc. can be suppressed.

[0053] According to the present invention, when a heat sink is bonded to an insulating circuit board, for example, the first metal member can be bonded at a low temperature via the copper sintered layer, so warping can be suppressed and bonding properties can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a cross-sectional view showing a multilayer bonded body according to an embodiment of the present invention.

[0055] Figure 2 This is a schematic cross-sectional view of a bonding material used for bonding a multilayer bonded body.

[0056] Figure 3 It is a cross-sectional view showing a multilayer bonded body according to another embodiment.

[0057] Figure 4 is a cross-sectional view showing still another multi-layer bonded body.

[0058] Figure 5 Yes means Figure 4 Flowchart of a method for manufacturing a multilayer bonded body and a subsequent method for manufacturing a semiconductor device.

[0059] Figure 6 Yes means Figure 4A cross-sectional view of a first lamination step in a method for manufacturing a multilayer bonded body.

[0060] Figure 7 It is a top view of the first aluminum plate having the groove portion formed therein.

[0061] Figure 8 is along Figure 7 The cross-sectional view taken along line GG is a partial cross-sectional view of the first aluminum plate having the groove portion.

[0062] Fig. 9 Yes means Figure 4 A cross-sectional view of a second lamination step in the method for producing a multilayer bonded body shown.

[0063] Fig.10 is used Figure 4 A cross-sectional view of a semiconductor device having a multilayer junction.

[0064] Fig.11 It means in manufacturing Fig.10 A cross-sectional view of a process of performing resin sealing in a semiconductor device.

[0065] Fig.12 It means for Figure 4 A cross-sectional view of an example of a multilayer bonded body in which the first metal member serves as a heat sink.

[0066] Fig.13 The first metal part is used as a heat sink with heat sink Fig.12 A cross-sectional view of an application example of a multilayer bonded body.

[0067] Fig.14 It means use Fig.13 A cross-sectional view of a semiconductor device having a multilayer junction.

[0068] Fig.15 Yes means Fig.14 Flowchart of a method for manufacturing a semiconductor device shown.

[0069] Fig.16 It means in Fig.14 A cross-sectional view showing a state in which an intermediate metal layer is formed on a first bonded body in a method for manufacturing a semiconductor device shown.

[0070] Fig.17 It means in Fig.14 A cross-sectional view of a second stacking step in a method for manufacturing a semiconductor device shown.

[0071] Fig.18 It means in Figure 4 A cross-sectional view of an example of a multilayer bonded body in which a second metal member is further bonded to the second aluminum plate of the multilayer bonded body via a copper sintered layer.

[0072] Fig.19 It means in Fig.18 A cross-sectional view of a second lamination step in the method for producing a multilayer bonded body shown.

[0073] Fig. 20 It means in Fig.18 sectional view of an example of a multilayer bonded body in which a fourth intermediate metal layer is further formed on the second metal member of the multilayer bonded body.

[0074] Fig.21 It means use Fig.18 A cross-sectional view of a semiconductor device having a multilayer junction.

[0075] Fig. 22 Yes means Fig.21 Flowchart of a method for manufacturing a semiconductor device shown.

[0076] Fig.23 It means in Fig.21 A cross-sectional view of a third stacking step in the method for manufacturing a semiconductor device shown. DETAILED DESCRIPTION

[0077] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0078] [Structure of Multilayer Joined Body 10]

[0079] like Figure 1 As shown, the multilayer assembly 10 of the first embodiment comprises: a ceramic substrate 11; a first aluminum plate 12 stacked on one surface of the ceramic substrate 11; a first intermediate metal layer 13 bonded to the surface of the first aluminum plate 12 on the opposite side to the ceramic substrate 11; a first copper sintered layer 14 bonded to the surface of the first intermediate metal layer 13 on the opposite side to the first aluminum plate 12; and a first metal component 15 bonded to the surface of the first copper sintered layer 14 on the opposite side to the first intermediate metal layer 13.

[0080] exist Figure 1 In the example shown, the first aluminum plate 12, the first intermediate metal layer 13, the first copper sintered layer 14 and the first metal component 15 are separated into a plurality of Figure 1 The ceramic substrate 11 is stacked in a state of being labeled A and B, thereby constructing a stacked portion with the same layer structure as shown by the reference numerals A and B, but it can also be constructed as one stacked portion instead of being separated. Of course, it can also be set to three or more stacked portions. Moreover, the two stacked portions shown in the figure are only different in size and are the stacked structure of the same component, so the reference numerals of each component are sometimes marked only in one of the stacked portions A and B (hereinafter, in Figure 3 The same also applies to etc.).

[0081] The ceramic substrate 11 is made of insulating material, such as aluminum nitride (AlN), silicon nitride (Si 3 N 4 ), aluminum oxide (Al 2 O 3 ) etc., and its plate thickness is, for example, 0.2 mm to 1.2 mm.

[0082] The first aluminum plate 12 is made of pure aluminum or aluminum alloy having a purity of 99 mass % or more. In the JIS standard, 1000 series pure aluminum can be used, and in particular, 1N90 (purity of 99.9 mass % or more: so-called 3N aluminum) or 1N99 (purity of 99.99 mass % or more: so-called 4N aluminum) can be used. The thickness is set to 0.4 mm to 1.6 mm, for example.

[0083] The first intermediate metal layer 13 includes any one of copper, nickel, silver, and gold, and is formed in a state of being closely attached to the surface of the first aluminum plate 12 by plating or the like. The first aluminum plate 12 and the first copper sintered layer 14 are bonded via the first intermediate metal layer 13. When the first intermediate metal layer 13 is silver or gold, a nickel film may be formed on the first aluminum plate 12 as a base layer, and the first intermediate metal layer 13 may be formed on the nickel film.

[0084] The first copper sintered layer 14 joins the first intermediate metal layer 13 and the first metal member 15 and is formed by heating and sintering a first bonding material 310 formed into a sheet by connecting a plurality of copper particles 311 with a binder (solvent) 312. Details will be described later.

[0085] The first metal member 15 is formed, for example, by a plate (copper plate) made of copper (oxygen-free copper) with a purity of 99.96% by mass or more, copper (tough pitch copper) with a purity of 99.90% by mass or more, or a copper alloy, or an aluminum plate with a purity of less than 99.90% by mass (a pure aluminum plate of so-called 2N aluminum (such as A1050) with a purity of 99.0% by mass or more in the JIS standard, or an aluminum plate made of an aluminum alloy such as A3003, A6063, or A5052). The thickness of the first metal member 15 is set, for example, to 0.5 mm to 1.5 mm.

[0086] (Details of the First Copper Sintered Layer 14)

[0087] The first copper sintered layer 14 is formed by pressurizing and heating the first bonding material 310, and for example, the "bonding sheet" described in Japanese Patent Application Laid-Open No. 2021-116463 filed by the present applicant can be used. Figure 2 As shown, the first bonding material 310 is composed of 90 mass % or more and 99 mass % or less of a plurality of copper particles 311 and 1 mass % or more and 10 mass % or less of a solvent 312 .

[0088] In this case, the average particle size (BET diameter) converted using a spherical model from the specific surface area of ​​the copper particles 311 according to JIS Z 8830 is 50 nm or more and 300 nm or less. The copper particles 311 can be generated by adjusting the pH of the aqueous dispersion of copper citrate to (2.0 or more and 7.5 or less), adding a hydrazine compound to mix in an inert gas atmosphere, and maintaining the mixed solution at a predetermined temperature (60° C. or more and 80° C. or less) in an inert gas atmosphere (1.5 hours or more and 2.5 hours or less) to reduce the dissolved copper ions. In addition, the copper particles 311 are coated with a film 313 of an organic substance (derived from citric acid), thereby suppressing oxidation.

[0089] The solvent 312 as a binder connecting the plurality of copper particles 311 has a boiling point of 150° C. or higher and is composed of one of an organic solvent or a polymer solvent, or two or more of these solvents, such as a diol compound or a triol compound.

[0090] When the first bonding material 310 is composed of the copper particles 311 and the solvent 312, the thickness t thereof is not limited, but can be, for example, 50 μm or more and 1000 μm or less, or can be 500 μm or more. In addition, the first bonding material 310 is not limited to a material in which all the copper particles 311 are formed into a sheet in an unsintered state, and a material in which a part of the copper particles 311 is sintered and connected and the remaining part is formed into a sheet in an unsintered state can also be used.

[0091] The first bonding material 310 is overlapped with the first intermediate metal layer 13 and further heated while being pressurized in the stacking direction, so that the solvent 312 in the first bonding material 310 or the film 313 around the copper particles 311 volatilizes, and the copper particles 311 are sintered to form the first copper sintered layer 14. The interface region of the first copper sintered layer 14 contains nickel or any one of copper, gold, and silver constituting the first intermediate metal layer 13.

[0092] The multilayer bonded body 10 is a laminated body in which a first aluminum plate 12, a first intermediate metal layer 13, a first copper sintered layer 14, and a first metal member 15 are sequentially bonded to a ceramic substrate 11, and can be used as an insulating circuit substrate with a surface 15a of the first metal member 15 as an electronic component mounting surface. In this case, for example, thermal conductive grease or the like can be applied to a surface 11b of the ceramic substrate 11 on the opposite side to the first aluminum plate 12, and the ceramic substrate 11 can be brought into contact with a heat sink or the like (not shown) for heat dissipation and fixed by screws or the like.

[0093] [Structure of Multilayer Bonded Body 16]

[0094] In the multilayer bonded body 10, Figure 3 2 shows a case where a metal plate made of aluminum or an aluminum alloy is used as the first metal member 15. Figure 3 As in the multilayer joint body 16 shown, on the surface of the first metal component 15 joined to the first copper sintered layer 14, a second intermediate metal layer 17 including any one of copper, nickel, silver and gold is formed by plating or the like, similarly to the first intermediate metal layer 13 of the first aluminum plate 12, and the second intermediate metal layer 17 is joined to the first copper sintered layer 14.

[0095] When the second intermediate metal layer 17 is made of silver or gold, a nickel film may be formed on the first metal member 15 as a base layer, and the second intermediate metal layer 17 may be formed on the base layer.

[0096] In these multilayer bonded bodies 10 and 16, grooves 131 may be formed on the surfaces of the members bonded by the first copper sintered layer 14 (see Figure 7 , Figure 8 Specifically, the groove 131 can be formed on the surface of the first aluminum plate 12 on which the first intermediate metal layer 13 is to be formed and on the surface of the first copper sintered layer 14 side of the first metal component 15 (in the multilayer joint body 16, the surface of the first metal component 15 on which the second intermediate metal layer 17 is to be formed). The groove 131 will be described later.

[0097] [Structure of the multilayer bonded body 20]

[0098] Moreover, Figure 1 The multi-layer bonded body 10 shown is based on Figure 4 As shown, a multilayer bonded body 20 can be formed by bonding a second aluminum plate 21 made of aluminum or an aluminum alloy to the other surface 11b of the ceramic substrate 11. When the multilayer bonded body 20 is an insulating circuit substrate, the second aluminum plate 21 can be used as a heat sink.

[0099] The second aluminum plate 21 is preferably set to have the same plate thickness as the first aluminum plate 12 or a plate thickness with a slight difference therefrom, but may be set to be thicker or larger in area than the first aluminum plate 12 in order to increase the heat capacity as a heat sink.

[0100] [Method for Manufacturing Multilayer Bonded Body 20]

[0101] right Figure 4 A method for manufacturing the multilayer bonded body 20 shown will be described.

[0102] Figure 5In the flowchart shown, each process in the range shown by E is a process for manufacturing the multilayer bonded body 20. That is, the manufacturing method comprises: a first lamination process, in which the first aluminum plate 12 and the second aluminum plate 21 are laminated on the ceramic substrate 11 via the brazing material 41 and the brazing material 42 to form the first laminated body 50; a first bonding process, in which the first laminated body 50 is bonded by pressurizing and heating to form the first bonded body 51; an intermediate metal layer forming process, in which the first intermediate metal layer 13 is formed on the surface of the first aluminum plate 12 of the first bonded body 51 on the side opposite to the ceramic substrate 11; a second lamination process, in which the first bonding material 310 and the first metal component 15 are sequentially laminated on the first intermediate metal layer 13 to form the second laminated body 52; and a second bonding process, in which the first bonding material 310 is sintered to form the first copper sintered layer 14 to bond the first intermediate metal layer 13 and the first metal component 15. The following is described in the order of the processes.

[0103] Figure 5 This shows the steps of manufacturing a semiconductor device by mounting electronic components and the like on the manufactured multilayer bonded body 20 and sealing the multilayer bonded body 20 with a resin, after the step indicated by E of manufacturing the multilayer bonded body 20. The method of manufacturing the semiconductor device will be described later.

[0104] (First Lamination Step)

[0105] like Figure 6 As shown in the figure, the first stacked body 50 is formed by laminating the first aluminum plate 12 on one surface 11a of the ceramic substrate 11 via the brazing material 41, and laminating the second aluminum plate 21 on the other surface 11b of the ceramic substrate 11 via the brazing material 42. Al-Si-based, Al-Ge-based, Al-Cu-based, Al-Mg-based, Al-Mn-based or Al-Si-Mg-based brazing materials are used as the brazing materials 41 and 42. The brazing materials 41 and 42 can be supplied as foils or as pastes.

[0106] As described above, in the case where the groove portion 131 is formed on the surface of the first aluminum plate 12 on the first copper sintered layer 14 side, Figure 7 and Figure 8 As shown in the cross-sectional view taken along the GG line, a groove 131 is formed from one side to the other side of the rectangular surface 12a of the first aluminum plate 12, and each groove 131 is arranged in parallel, so that the surface 12a of the first aluminum plate 12 is formed into a concave-convex shape. The cross section of the groove 131 is formed into a V-shaped cross section, for example.

[0107] Each groove 131 is formed with the same size. For example, when the pitch of the grooves 131 is set to a [mm], the depth of the grooves 131 is set to b [mm], the width of the grooves 131 is set to c [mm], and the width of the flat portion 132 provided between the grooves 131 is set to d [mm], the relationship of a>d>c≥b is set. Thus, when the surface 12a of the first aluminum plate 12 is viewed from above, the area s2 occupied by the flat portion 132 is set to be larger than the area s1 occupied by the grooves 131 (s2>s1).

[0108] The groove portion 131 is formed to have a size that remains as a groove portion even after the first intermediate metal layer 13 is formed on the surface of the first aluminum plate 12 .

[0109] The same groove portion 131 may be formed on the surface of the first metal member 15 on the first copper sintered layer 14 side.

[0110] (First Bonding Step)

[0111] The first bonded body 51 is formed by heating the first stacked body 50 while being pressed in the stacking direction and then cooling it (see Fig. 9 ), the first bonded body 51 is formed by bonding the first aluminum plate 12 to one surface 11 a of the ceramic substrate 11 and bonding the second aluminum plate 21 to the other surface 11 b of the ceramic substrate 11 .

[0112] At this time, the brazing materials 41 and 42 are melted by heating, and then diffused into the first aluminum plate 12 or the second aluminum plate 21, and the first aluminum plate 12 and the second aluminum plate 21 are firmly bonded to the ceramic substrate 11. The components of the brazing materials 41 and 42 may be completely diffused into the first aluminum plate 12 or the second aluminum plate 21, or may remain as a layer.

[0113] The bonding conditions at this time are not necessarily limited, but it is preferable to hold the bonding in a vacuum atmosphere at a pressure of 0.1 MPa to 3.4 MPa in the lamination direction and at a heating temperature of 610° C. to 655° C. for 1 minute to 60 minutes.

[0114] (Intermediate Metal Layer Formation Step)

[0115] like Fig. 9 As shown, the first intermediate metal layer 13 is formed by plating or the like on the surface of the first aluminum plate 12 of the first bonded body 51 on the side opposite to the ceramic substrate 11. It can be formed by a thin film forming technique other than plating, and can also be formed by arranging any foil of copper, nickel, silver, and gold on the surface of the first aluminum plate 12 and performing diffusion bonding.

[0116] (Second Lamination Step)

[0117] On the first intermediate metal layer 13, as Fig. 9 As shown by the arrow, the first bonding material 310 is arranged, and the first metal member 15 is placed on the first bonding material 310 to form the second stacked body 52 .

[0118] (Second Bonding Step)

[0119] The first bonding material 310 is sintered by heating the second stack 52 while being pressurized in the stacking direction. At this time, the pressure in the stacking direction is preferably 5 MPa to 10 MPa and the heating temperature is preferably 250° C. to 300° C. for 3 minutes to 60 minutes.

[0120] By this heating and pressurization, the solvent 312 of the first bonding material 310 and the film 313 around the copper particles 311 are burned, and the plurality of copper particles 311 are sintered to form the first copper sintered layer 14. Then, the first intermediate metal layer 13 and the first metal member 15 are bonded to the first copper sintered layer 14 to form Figure 4 The multi-layer bonded body 20 is shown.

[0121] The multilayer bonded body 20 manufactured in this manner can be used as an insulating circuit board with a heat sink, in which the surface 15 a of the first metal member 15 is used as an electronic component mounting surface and the second aluminum plate 21 is used as a heat sink.

[0122] In this manufacturing method, first, the first aluminum plate 12 and the second aluminum plate 21 are bonded to both surfaces of the ceramic substrate 11 in a first bonding step, and then the first metal member 15 is bonded to the first aluminum plate 12 via the first copper sintered layer 14 in a second bonding step.

[0123] In this case, in the first joining step, although high temperature treatment is performed because the joining is performed using the brazing material 41, warping after joining is unlikely to occur because the same type of aluminum plates 12 and 21 are joined to both surfaces of the ceramic substrate 11. In particular, by using high-purity aluminum as the first aluminum plate 12 and the second aluminum plate 21, warping is unlikely to occur, and by setting the plate thickness to be the same or to the same extent, warping is even less likely to occur.

[0124] Then, in the subsequent second joining process, since the components 13, 14, and 15 are joined only on one surface side of the ceramic substrate 11 (the first aluminum plate 12 side), an imbalance occurs in the stacked structure on both sides of the ceramic substrate 11. However, since the heating temperature is suppressed and the joining is performed at a low temperature of above 250°C and below 300°C, the occurrence of warping can be suppressed.

[0125] Thus, in the multilayer bonded body (insulated circuit board with heat sink) 20, good bonding with suppressed warping can be achieved by using the first bonding material 310, so that the bonding area between the first metal member 15 and the first aluminum plate 12 can be enlarged.

[0126] That is, when copper paste is used to bond the first metal member 15 to the first aluminum plate 12, since the organic component may cause voids due to heating during bonding, a large amount of copper paste cannot be used, which may limit the increase in the bonding area of ​​the first metal member 15 or the first aluminum plate 12. In contrast, in the present embodiment, since the first bonding material 310 formed in a sheet shape is used and the organic component is reduced compared to copper paste, the generation of voids in the second bonding step can be suppressed.

[0127] In this case, although the planar dimensions of the first aluminum plate 12 and the first metal member 15, that is, the size of the surface (joining surface) joined by the first joining material 310 is not particularly limited, a size larger than 100 mm can be used. 2 In particular, when a bonding sheet formed by connecting a plurality of copper particles 311 with an adhesive to form a sheet-like shape is used as the first bonding material 310, or when a copper sintered sheet formed by partially sintering the copper particles 311 to form a sheet-like state is used as the first bonding material 310, the surface of the first copper sintered layer 14 that is bonded to the first metal component 15 can be increased compared to the case of using copper paste.

[0128] Even if it is greater than 100mm 2 In the case of an area of ​​200 mm, a copper sintered sheet can be used as the first bonding material 310 for bonding to reduce the gaps caused by the volatilization of the adhesive. The size of the bonding surface can be 200 mm 2 Above, can also be 500mm 2 Furthermore, the upper limit of the joint surface is not particularly limited and can be 2000 mm 2 Below, can also be 1000mm 2 the following.

[0129] The thickness of the first copper sintered layer 14 in the stacking direction is preferably, for example, not less than 50 μm and not more than 1000 μm, and may be not less than 500 μm. In particular, when a copper sintered sheet formed by partially sintering the copper particles 311 into a sheet shape is used as the first bonding material 310 for bonding, the thickness of the first copper sintered layer 14 in the stacking direction can be made thicker than when a copper paste is used.

[0130] Since the first intermediate metal layer 13 including any one of copper, nickel, silver and gold is formed on the surface of the first aluminum plate 12 in the intermediate metal layer forming process, the first aluminum plate 12 and the first copper sintered layer 14 can be firmly bonded via the first intermediate metal layer 13 in the second bonding process.

[0131] Furthermore, by forming the groove 131 on the surface of the first aluminum plate 12 and the surface of the first metal member 15 that are opposite to the first copper sintered layer 14, even if gas is generated from the organic component of the first bonding material 310 due to heating during bonding, it will flow out to the outside through the groove 131, thereby further suppressing the generation of voids. As a result, bonding is further improved and it can further contribute to the expansion of the bonding area.

[0132] [Structure of Semiconductor Device 100]

[0133] Can Figure 4 The multilayer bonded body 20 shown in the figure is manufactured by mounting an electronic component 70 such as a power device on the surface 15a of the first metal member 15. Fig.10 A semiconductor device 100 such as a power module is shown. Fig.10 In the semiconductor device 100 shown, an electronic component 70 is bonded to a surface 15 a of a first metal member 15 , and a leading end portion of a lead frame 71 made of a copper alloy is bonded to the electronic component 70 and sealed with an insulating resin 72 .

[0134] In this case, the insulating resin 72 is embedded in the entire surface 21a of the second aluminum plate 21 on the side opposite to the ceramic substrate 11 and the end of the lead frame 71 is exposed. In the example shown in the figure, a plurality of electronic components 70 are mounted, and the lead frames 71 are connected to the electronic components 70 and a part of the first metal member 15, respectively, and the end of each lead frame 71 is exposed in a state of protruding from the insulating resin 72. Reference numeral 73 denotes solder.

[0135] [Method of Manufacturing Semiconductor Device 100]

[0136] The method of manufacturing the semiconductor device 100 is described as follows. Figure 5 As described in the manufacturing process of the multilayer bonded body 20 shown in E, after the second bonding process, there is a mounting process of mounting the electronic component 70 and the like and a resin sealing process of sealing the electronic component 70 and the like with an insulating resin 72 after the mounting process. These processes are described below.

[0137] (Installation process)

[0138] A film is formed on the surface of the first metal member 15 in the multilayer bonded body 20 by nickel plating or the like, and the electronic component 70 is bonded thereto using solder 73. As the solder 73, a solder such as Sn-Ag-Cu, Zn-Al, Sn-Ag, Sn-Cu, Sn-Sb or Pb-Sn is used. Then, one end of the lead frame 71 is connected to the electronic component 70 using solder 73. The lead frame 71 is made of copper or a copper alloy and is formed in a narrow plate shape or the like.

[0139] When a plurality of electronic components 70 are connected to each other, the electronic components 70 may be connected by wire bonding, and when a lead frame 71 and the electronic component 70 are connected, they may be connected by solder 73 or wire bonding. In this case, the bonding wire is embedded in the insulating resin 72 in the subsequent resin sealing step.

[0140] (Resin sealing process)

[0141] The entire multilayer bonded body 20 including the electronic component 70 is sealed with an insulating resin 72 while the surface 21 a of the second aluminum plate 21 opposite to the ceramic substrate 11 and the ends of each lead frame 71 opposite to the electronic component 70 are exposed.

[0142] Specifically, if Fig.11 As shown, the multilayer assembly 20 is placed in the cavity 81 of the mold 80 using the injection molding mold 80, with the surface 21a of the second aluminum plate 21 in contact with the inner surface of the mold 80. The end of each lead frame 71 on the side opposite to the electronic component 70 is placed in the gap of the mold and maintained so as not to be exposed to the cavity 81.

[0143] If the Fig.11 As shown, the multilayer bonded body 20 is fixed in a state arranged in an injection molding mold 80 so as not to move in a cavity 81, and an insulating resin 72 such as epoxy resin is injected into the cavity 81. When the mold 80 is opened after the insulating resin 72 is cured, the semiconductor device 100 sealed by the insulating resin 72 can be taken out.

[0144] The semiconductor device 100 manufactured in this way (refer to Fig.10 ) is used in a state where conductive grease or the like is applied to the surface 21a of the second aluminum plate 21 exposed from the insulating resin 72 and the surface 21a is in contact with a cooler or the like.

[0145] exist Figure 4 In the multilayer bonded body 20 shown, Figure 3 As shown in FIG. 1 , a second intermediate metal layer 17 may be formed between the first metal component 15 and the first copper sintered layer 14 in the intermediate metal layer forming process. Figure 5 In the intermediate metal layer forming step shown in FIG. 1 , the first intermediate metal layer 13 is formed on the first aluminum plate 12, and the second intermediate metal layer 17 is formed on the surface of the first metal component 15. In the second lamination step, the second intermediate metal layer 17 on the surface of the first metal component 15 is bonded to the first bonding material 310 (reference Fig. 9 ) are placed in contact with the first metal member 15 and joined in the second joining step. This is effective when the first metal member 15 includes aluminum or an aluminum alloy.

[0146] exist Fig.10 In the semiconductor device 100 shown in FIG. Figure 4 Although the surface 15a of the first metal member 15 in the multilayer bonded body 20 is shown as an example of the electronic component mounting surface, the surface 21a of the second aluminum plate 21 opposite to the ceramic substrate 11 may be used as the electronic component mounting surface.

[0147] [Structure of Multilayer Bonded Body 40]

[0148] and Figure 4 on the contrary, Fig.12 The multilayer bonded body 40 is shown in which the surface 21a of the second aluminum plate 21 opposite to the ceramic substrate 11 is used as the electronic component mounting surface. Figure 4 The same reference numerals (in Fig.13 The same applies later), but for ease of Figure 4 For comparison, the first aluminum plate 12 on one side of the ceramic substrate 11 is shown as one laminated portion, and the second aluminum plate 21 is separated into two parts, A and B. The laminated structure of the multilayer bonded body 40 is similar to Figure 4 The multi-layered joints 20 shown are identical.

[0149] [Structure of Multilayer Bonded Body 45]

[0150] Fig.13 express Fig.12 A multilayer bonded body 45 is an application example of the multilayer bonded body 40 shown in FIG. In the multilayer bonded body 45, a first aluminum plate 12 is bonded to one surface of a ceramic substrate 11, a second aluminum plate 21 is bonded to the other surface of the ceramic substrate 11, a first intermediate metal layer 13 is formed on the surface of the first aluminum plate 12, a third intermediate metal layer 18 is formed on the surface of the second aluminum plate 21, and a first metal component 60 is bonded to the first intermediate metal layer 13 of the first aluminum plate 12 via a first copper sintered layer 14. As an insulating circuit substrate, the second aluminum plate 21 corresponds to a circuit layer, and the first metal component 60 corresponds to a heat sink.

[0151] In this Fig.13In the example shown, the first intermediate metal layer 13 is formed by plating containing any one of copper, nickel, silver and gold. In order to improve the adhesion between the second aluminum plate 21 as a circuit layer and the electronic components, a third intermediate metal layer 18 is also formed on the surface of the second aluminum plate 21 by plating containing any one of copper, nickel, silver and gold.

[0152] The first aluminum plate 12 is shown as a laminate, but the second aluminum plate 21 constituting the circuit layer is Figure 1 Similarly, they are shown separately as A and B. The first metal member 60 includes any one of aluminum, aluminum alloy, copper and copper alloy, and is formed in the shape of a heat sink with fins in which a plurality of pin-shaped or plate-shaped fins 62 are erected parallel to each other on one surface of a flat metal plate portion 61.

[0153] [Structure of Semiconductor Device 110]

[0154] Next, a semiconductor device 110 using the multilayer bonded structure 45 will be described.

[0155] like Fig.14 As shown, in the semiconductor device 110, an electronic component 70 is bonded to the third intermediate metal layer 18 formed on the second aluminum plate 21 indicated by reference numeral B of the multilayer bonded body 45 via solder 73, and a lead frame 71 is bonded to the electronic component 70 and the third intermediate metal layer 18 on the second aluminum plate 21 indicated by reference numeral A via solder 73, and the electronic component 70 is sealed with an insulating resin 72 in a state where the ends of the first metal component (heat sink) 60 and each lead frame 71 are exposed. Specifically, the entire first metal component 60 is exposed from the insulating resin 72 at the interface between the first intermediate metal layer 13 and the first copper sintered layer 14 on the surface of the first aluminum plate 12.

[0156] [Method of Manufacturing Semiconductor Device 110]

[0157] If according to Fig.15 The flowchart shown in FIG. 1 illustrates a method for manufacturing the semiconductor device 110. First, solder 41 and solder 42 (see FIG. 1 ) are respectively formed on both sides of the ceramic substrate 11. Figure 6 ) stacking the first aluminum plate 12 and the second aluminum plate 21 to form a first stack (first stacking step), and pressurizing and heating the first stack to bond, thereby forming a Fig.16 The first bonded body 53 shown (first bonding step).

[0158] The process so far is Figure 4 The steps for forming the multilayer bonded body 20 are the same. In addition, it is preferable to form a plurality of grooves 131 on the surface of the first aluminum plate 12 on the side opposite to the ceramic substrate.

[0159] Next, a first intermediate metal layer 13 including any one of copper, nickel, silver and gold is formed on the surface of the first aluminum plate 12 of the first bonded body 53 by plating or the like (intermediate metal layer forming step). Fig.16 In the example shown, in order to improve the bonding property with the electronic parts, a film of the third intermediate metal layer 18 including any one of copper, nickel, silver and gold is also formed on the surface of the second aluminum plate 21. When the first intermediate metal layer 13 or the third intermediate metal layer 18 is composed of silver or gold, it is preferable to form a nickel film as a base layer and form the first intermediate metal layer 13 or the third intermediate metal layer 18 thereon.

[0160] After the intermediate metal layer forming step, the electronic component 70 is bonded to the second aluminum plate 21 using solder 73 , and one end of the lead frame 71 is connected to the electronic component 70 (mounting step).

[0161] Then, if Fig.17 As shown, the entirety including the electronic component 70 is sealed by an insulating resin 72 while the first intermediate metal layer 13 on the surface of the first aluminum plate 12 opposite to the ceramic substrate 11 and the end of each lead frame 71 on the side opposite to the electronic component 70 are exposed (resin sealing process).

[0162] Then, if Fig.17 As shown by the arrow, the first bonding material 310 and the first metal component 60 are sequentially stacked on the first intermediate metal layer 13 exposed from the insulating resin 72 to form the second stacked body 54 (second stacking step). In this case, the first metal component 60 is formed as a heat sink with a heat sink having a plurality of heat sinks 62 on one surface of a metal plate portion 61, so the surface 61a of the metal plate portion 61 on the side opposite to the heat sink 62 is in contact with the first bonding material 310.

[0163] As described above, the first bonding material 310 is composed of 90 mass % to 99 mass % of the plurality of copper particles 311 and 1 mass % to 10 mass % of the solvent (binder) 312 , and the copper particles 311 are covered with the film 313 of an organic substance.

[0164] In the first metal component 60, the surface in contact with the first bonding material 310 (at Fig.17 In the case of the first metal component 60, an intermediate metal layer (second intermediate metal layer) containing any one of copper, nickel, silver and gold is formed on the surface 61a of the metal plate portion 61 on the side opposite to the heat sink 62. In particular, when the first metal component 60 is formed of aluminum or an aluminum alloy, the formation of the intermediate metal layer enables good bonding in the subsequent second bonding step.

[0165] Furthermore, in the first metal member 60, a plurality of grooves ( Figure 7 and Figure 8 The groove portion 131 shown).

[0166] Then, the second stack 54 is pressurized and heated in the stacking direction to sinter the copper particles 311 of the first bonding material 310, and the first metal member 60 and the first intermediate metal layer 13 are bonded via the first copper sintered layer 14 (second bonding step), thereby forming a Fig.14 The semiconductor device 110 shown is shown. At this time, it is preferable to maintain the pressure at 5 MPa to 10 MPa and the heating temperature at 250° C. to 300° C. for 3 minutes to 60 minutes.

[0167] In this manufacturing method, after the mounting step and the resin sealing step, a second bonding step accompanied by pressurization and heating is carried out. However, in this second bonding step, bonding is performed through the first copper sintered layer 14, the heating temperature is suppressed, and bonding is performed at a low temperature of 250°C to 300°C, thereby suppressing thermal effects on the electronic component 70, the insulating resin 72, etc.

[0168] [Structure of Multilayer Bonded Body 30]

[0169] Also available in Figure 4 The second metal member is further bonded to the second aluminum plate 21 of the multilayer bonded body 20 via a copper sintered layer.

[0170] Fig.18 This multilayer bonded body 30 is shown, in which a second metal member 65 is bonded to a second aluminum plate 21 via a third intermediate metal layer 18 and a second copper sintered layer 19. The third intermediate metal layer 18 contains any one of copper, nickel, silver and gold. The second copper sintered layer 19 is formed by sintering copper particles 311 together, similarly to the first copper sintered layer 14.

[0171] In this Fig.18 In the case of the multilayer bonded body 30 shown in FIG. Fig.13 The first metal member 60 similarly includes any one of aluminum, aluminum alloy, copper, and copper alloy, and is formed in the shape of a heat sink with fins having a plurality of fins 62 on one surface of a flat metal plate portion 61 .

[0172] That is, in Figure 4 In the multilayer bonded body 20 shown in the figure, the second aluminum plate 21 can be used as a heat sink, but in this Fig.18 In the multilayer bonded body 30 shown, the second aluminum plate 21 is used as a metal plate for heat transfer, and a second metal member 65 as a heat sink is further bonded to the second aluminum plate 21 .

[0173] [Method for Manufacturing Multilayer Bonded Body 30]

[0174] When manufacturing the multilayer bonded body 30, Figure 5 As shown in the range of the reference numeral E, the first aluminum plate 12 and the second aluminum plate 21 are brazed and bonded to the ceramic substrate 11 through the first lamination step and the first bonding step, thereby forming a first bonded body 51 .

[0175] Next, through the intermediate metal layer forming step, the first intermediate metal layer 13 and the third intermediate metal layer 18 are formed on the surfaces of the first aluminum plate 12 and the second aluminum plate 21 on the side opposite to the ceramic substrate 11. Fig.19 As shown, the first metal member 15 is disposed on the first intermediate metal layer 13 via the first bonding material 310 , and the second metal member 65 is disposed on the third intermediate metal layer 18 via the second bonding material 320 (second lamination step), thereby forming a second laminate 55 .

[0176] The second bonding material 320 is similar to the first bonding material 310 and is composed of 90 mass % or more and 99 mass % or less of a plurality of copper particles 311 and 1 mass % or more and 10 mass % or less of a solvent 312 (see Figure 2 ).

[0177] Then, while the second stack 55 is pressurized at a pressure of not less than 5 MPa and not more than 10 MPa in the stacking direction, the copper particles 311 of the first bonding material 310 and the second bonding material 320 are sintered by maintaining the heating temperature at not less than 250°C and not more than 300°C for not less than 3 minutes and not more than 60 minutes to form a first copper sintered layer 14 and a second copper sintered layer 19, and the first intermediate metal layer 13 and the first metal component 15 on the surface of the first aluminum plate 12, and the third intermediate metal layer 18 and the second metal component 65 on the surface of the second aluminum plate 21 are respectively bonded (second bonding process).

[0178] The multilayer bonded body 30 manufactured in this manner can be used as an insulating circuit board with a heat sink, in which the surface 15 a of the first metal member 15 is used as an electronic component mounting surface and the second metal member 65 is used as a heat sink.

[0179] In addition, in the multilayer bonded body 30, when the second metal member 65 is formed of a material containing aluminum or an aluminum alloy, as shown in FIG. Fig. 20 As shown in the multilayer bonded body 90 , the fourth intermediate metal layer 22 is preferably formed on one surface of the second metal member 65 , that is, on the surface of the metal plate portion 61 (between the second metal member 65 and the second copper sintered layer 19 ).

[0180] The fourth intermediate metal layer 22 includes any one of copper, nickel, silver and gold, and can improve the bonding between the second metal member 65 and the second copper sintered layer 19. A groove 131 may be formed on the surface of the metal plate portion 61 of the second metal member 65 bonded to the second copper sintered layer 19.

[0181] [Structure of Semiconductor Device 120]

[0182] The multilayer bonded body 30 can also be configured as Fig.21 The semiconductor device 120 shown in FIG. Fig.10 The semiconductor device 100 shown in the figure has a semiconductor device 120 in which a third intermediate metal layer 18 including any one of copper, nickel, silver and gold is formed on the surface 21a of the second aluminum plate 21 exposed from the insulating resin 72, and a second metal component 65 in the shape of a heat sink with a heat sink including any one of aluminum, aluminum alloy, copper and copper alloy is bonded to the third intermediate metal layer 18 via a second copper sintered layer 19.

[0183] [Method of Manufacturing Semiconductor Device 120]

[0184] When manufacturing the semiconductor device 120, Fig. 22 As shown, the first aluminum plate 12 and the second aluminum plate 21 are stacked on the ceramic substrate 11 via the brazing materials 41 and 42 (first stacking process), and pressurized and heated to form a first bonded body (first bonding process). For the first bonded body, the first intermediate metal layer 13 and the third intermediate metal layer 18 are formed on at least one side of the first aluminum plate 12 and the second aluminum plate 21 opposite to the ceramic substrate 11 (intermediate metal layer forming process), and the first metal component 15 is stacked on the first intermediate metal layer 13 via the first bonding material 310 (second stacking process).

[0185] Next, the first bonding material 310 is sintered by applying pressure and heat, and the first intermediate metal layer 13 and the first metal member 15 are bonded to each other via the first copper sintered layer 14 (second bonding step).

[0186] Thereafter, the electronic component 70 and the lead frame 71 are joined to the surface of the first metal member 15 by solder 73 (mounting process), and the electronic component 70 and the like are sealed by insulating resin 72 while leaving the surface of the third intermediate metal layer 18 and the end of the lead frame 71 exposed (resin sealing process).

[0187] Through the processes so far, manufacturing and Fig.10 The structure of the semiconductor device 100 shown in FIG. 1 is similar to that of the semiconductor device 100 shown in FIG. 1 in that the third intermediate metal layer 18 is formed on the surface 21 a of the second aluminum plate 21 exposed from the insulating resin 72 .

[0188] Then, if Fig.23 As shown by arrows, the second bonding material 320 and the second metal member 65 are sequentially stacked on the third intermediate metal layer 18 to form a third stacked body 56 (third stacking step).

[0189] Finally, the third laminate 56 is pressurized and heated to sinter the copper particles of the second bonding material 320 to form a second copper sintered layer 19, and the third intermediate metal layer 18 on the surface of the second aluminum plate 21 and the second metal component 65 are bonded via the second copper sintered layer 19 (third bonding step). Fig.21 A semiconductor device 120 is shown.

[0190] In the manufacturing method of the semiconductor device 120, after the mounting step and the resin sealing step, a third bonding step accompanied by pressurization and heating is also implemented. However, in this third bonding step, bonding is performed through the second copper sintered layer 19, the heating temperature is suppressed, and bonding is performed at a low temperature of 250°C to 300°C, thereby suppressing the thermal influence on the electronic component 70 or the insulating resin 72, etc.

[0191] The present invention is not limited to the above embodiments.

[0192] The first aluminum plate 12 and the second aluminum plate 21 joined to the ceramic substrate 11 are preferably formed of a material containing aluminum or an aluminum alloy, thereby forming a structure composed of aluminum or an aluminum alloy, but the first metal parts 15, 60 and the second metal part 65 can be composed of a material containing any one of aluminum, aluminum alloy, copper and copper alloy.

[0193] In order to improve the bonding between the first aluminum plate 12 and the second aluminum plate 21 and the copper sintered layers 14 and 19, intermediate metal layers 13 and 18 containing any one of copper, nickel, silver and gold are formed on the surfaces of the first aluminum plate 12 and the second aluminum plate 21. When the first metal member 15 and 60 and the second metal member 65 are also formed of a material containing aluminum or an aluminum alloy, it is preferable to form an intermediate metal layer (second intermediate metal layer 17) containing any one of copper, nickel, silver and gold on the bonding surface with the copper sintered layers 14 and 19.

[0194] When the first metal members 15 and 60 and the second metal member 65 are formed of a material containing copper or a copper alloy, an intermediate metal layer containing any one of copper, nickel, silver and gold may be formed on the bonding surface with the copper sintered layer.

[0195] Furthermore, grooves 131 may be formed on the surfaces of the first aluminum plate 12 and the second aluminum plate 21 bonded to the copper sintered layer, and on the surfaces of the first metal members 15, 60, and the second metal member 65. In this case, even if gas is generated from the organic components of the bonding materials 310, 320 due to heating during bonding, it will flow out to the outside through the grooves 131, so that the generation of voids can be further suppressed.

[0196] Example

[0197] In order to confirm the effect of the present invention, an experiment was conducted.

[0198] (1) Production of the First Bonded Body

[0199] First, aluminum plates are stacked on both sides of a ceramic substrate via brazing material, and heated while being pressed in the stacking direction, thereby forming a first aluminum plate 12 on one side of the ceramic substrate 11 and a second aluminum plate 21 on the other side of the ceramic substrate 11, thereby manufacturing a first bonded body.

[0200] (1-1) Material of the First Bonding Body

[0201] Ceramic substrate: Si 3 N 4 (Thickness 0.32mm)

[0202] First aluminum plate and second aluminum plate: 4N aluminum (thickness 0.6mm, length 30mm, width 40mm)

[0203] Brazing material: Brazing material foil composed of Al-7.5 mass% Si alloy (thickness 0.02 mm)

[0204] (1-2) Manufacturing conditions of the first bonded body

[0205] Bonding pressure: 0.2MPa

[0206] Heating temperature: 650℃

[0207] Hold time: 30 minutes

[0208] Joining atmosphere: vacuum

[0209] (2) Production of the Second Bonded Body

[0210] Next, on the surface of the first aluminum plate 12 on the opposite side to the ceramic substrate 11, a first intermediate metal layer 13 composed of a plated film of any one of copper, nickel, silver and gold (Examples 1 to 9) is formed by plating treatment, and the first intermediate metal layer 13 is heated in a state where the first metal component 15 is stacked via the first bonding material 310 to form a first copper sintered layer 14, thereby bonding the first metal component 15 to manufacture a second bonded body (specimen).

[0211] Second bonded bodies (samples) were manufactured in the same manner as in Examples 1 to 9 except that the first intermediate metal layer 13 was not formed in Comparative Example 1 and a chrome plating (Cr plating) film was formed as the first intermediate metal layer 13 in Comparative Example 2.

[0212] The first metal member 15 is formed of an aluminum plate or a copper plate in a rectangular shape and is 30 mm long and 40 mm wide. The first intermediate metal layer (plated film) of each embodiment is as shown in Table 1. When the first intermediate metal layer 13 is composed of chromium, gold or silver, a nickel-plated film is formed on the surface of the first aluminum plate 12 as a base layer.

[0213] (2-1) Groove

[0214] In Example 8 of the second bonded body as a sample, the groove 131 is formed on the surface of the first aluminum plate 12 on which the first intermediate metal layer 13 is to be formed. In the groove 131, Figure 7 The pitch a of the grooves 131 shown (the interval of the deepest part) is 1.5 [mm], the depth b of the grooves 131 is 0.3 [mm], the width c of the grooves 131 is 0.5 [mm], and the width d of the flat portion 132 provided between the grooves 131 is 1.0 [mm]. Twenty grooves 131 extending from one edge to the other are formed on the surface bonded to the first copper sintered layer 14.

[0215] (2-2) Regarding the Bonding Surface of the First Metal Member 15 and the First Copper Sintered Layer 14

[0216] The following components were prepared as the first metal component 15: these components were made of aluminum alloy (JIS6063 series) or copper alloy (JIS1020 series), and on the surface bonded to the first copper sintered layer 14, a nickel-plated film was provided as the second intermediate metal layer 17 by surface treatment (Examples 2 to 4, Comparative Example 2) and no plated film (second intermediate metal layer) was provided (Examples 1, 5 to 9, Comparative Example 1). The materials of the first metal component 15 and the second intermediate metal layer of each example are described in Table 1.

[0217] (2-3) Regarding the First Bonding Material

[0218] The first bonding material is a Cu sintered material composed of copper particles, and the copper particles are sintered by heating, thereby bonding the first intermediate metal layer 13 and the first metal component 15 (or the second intermediate metal layer 17 on the surface thereof). In Examples 1 to 7 and 9, copper particles 311 are connected by a solvent 312 to form a sheet-like bonding material, and in Example 8 and Comparative Examples 1 and 2, a paste bonding material is used.

[0219] (2-4) Production conditions of the second bonded body

[0220] Pressure: 5MPa

[0221] Heating temperature: 300℃

[0222] Hold time: 15 minutes

[0223] Joining atmosphere: vacuum

[0224] Sheet-shaped bonding material: 300 μm thick, with the same vertical and horizontal dimensions as the aluminum plate

[0225] (2-5) About resin sealing

[0226] In Example 9, before the second bonding step, the second aluminum plate of the first bonded body was sealed with an insulating resin in a state where the surface on the side opposite to the ceramic substrate was exposed.

[0227] (3) Evaluation of bonding rate

[0228] (3-1) Evaluation method

[0229] The bonding interface between the first aluminum and the first metal member in the second bonded body is observed using an ultrasonic flaw detection device, and an ultrasonic image of the bonding interface is processed and evaluated.

[0230] As an evaluation method, the bonding rate was calculated by the following formula (1).

[0231] Bonding rate (%) = [{(bonding area) - (peeling area)} / (bonding area)] × 100

[0232] In the ultrasonic flaw detection image (binarized image), the joined parts are shown in black, whereas the peeled parts (unjoined parts) are shown in white, and therefore the total area of ​​the white parts is taken as the peeled area.

[0233] The case where the bonding rate is 90% or more is qualified, among which the case where it is 97% or more is "A", and the case where it is 90% or more and less than 97% is "B". In addition, the case where the bonding rate is 0% or more and less than 90% is unqualified (NG) and marked as "C".

[0234] These results are shown in Table 1.

[0235] In Table 1, regarding the first intermediate metal layer, the copper-plated film is represented as "Cu-plated film", the nickel-plated film is represented as "Ni-plated film", the gold-plated film is represented as "Au-plated film", the silver-plated film is represented as "Ag-plated film", the chrome-plated film is represented as "Cr-plated", and the state in which the first intermediate metal layer is not formed is represented as "unplated". As the form of the bonding material, the sheet-like bonding material is represented as "sheet", and the paste-like bonding material is represented as "paste".

[0236] [Table 1]

[0237]

[0238] (3-2) Evaluation

[0239] As shown in Table 1, it can be confirmed that in the second bonded bodies of Examples 1 to 9, the bonded state is good, there is no or little unbonded portion in the bonded interface, and it is difficult to peel off.

[0240] In Examples 1 to 7 and 9, the copper particles 311 of the sheet-like bonding material are sintered to form a copper sintered layer, and the copper sintered layer suppresses the generation of gaps between the first aluminum plate and the first metal component, thereby bonding the first aluminum plate and the first metal component in a good bonding state. In Example 8, although copper paste is used, a groove is formed on the first aluminum plate, so the bonding state is good.

[0241] As a result of visual inspection of Example 9 in which the second bonding step was performed after sealing with the insulating resin, no thermal influence (discoloration, deformation, etc.) on the insulating resin was confirmed.

[0242] On the other hand, in the second bonded bodies of Comparative Examples 1 and 2, the bonding rates were both less than 90%, and non-bonding and peeling at the interface were confirmed.

[0243] Industrial Applicability

[0244] When the heat sink is bonded to an insulating circuit board, for example, the first metal member can be bonded at a low temperature via the copper sintered layer, so warping can be suppressed and bonding properties can be improved.

[0245] Description of Reference Numerals

[0246] 10, 16, 20, 30, 40, 45, 90 multi-layer joints

[0247] 11 Ceramic Substrate

[0248] 12 First Aluminum Plate

[0249] 13. First intermediate metal layer

[0250] 14 First copper sintering layer

[0251] 15, 60 First metal part

[0252] 17 Second intermediate metal layer

[0253] 18 Third intermediate metal layer

[0254] 21 Second Aluminum Plate

[0255] 41, 42 solder

[0256] 50 first stack

[0257] 51, 53 First joint

[0258] 52, 54, 55 Second stack

[0259] 56 Third stack

[0260] 65 Second metal part

[0261] 70 Electronic parts

[0262] 71 Lead frame

[0263] 72 Insulating resin

[0264] 73 Solder

[0265] 80 Injection molding mold

[0266] 81 Cavity

[0267] 100, 110, 120 Semiconductor devices

[0268] 131 Groove

[0269] 132 Flat part

[0270] 310 First bonding material

[0271] 320 Second bonding material

Claims

1. A multilayer bonded body, characterized in that: have: Ceramic substrate; a first aluminum plate bonded to one surface of the ceramic substrate and comprising aluminum or an aluminum alloy; a first intermediate metal layer bonded to a surface of the first aluminum plate opposite to the ceramic substrate and comprising any one of copper, nickel, silver and gold; a first copper sintered layer bonded to a surface of the first intermediate metal layer on a side opposite to the first aluminum plate; and The first metal member is bonded to a surface of the first copper sintered layer opposite to the first intermediate metal layer, and includes any one of aluminum, an aluminum alloy, copper, and a copper alloy.

2. The multilayer bonded body according to claim 1, characterized in that: The first metal component comprises aluminum or an aluminum alloy, A second intermediate metal layer including any one of copper, nickel, silver, and gold is formed between the first metal member and the first copper sintered layer.

3. The multilayer bonded body according to claim 1 or 2, characterized in that: A second aluminum plate made of aluminum or an aluminum alloy is bonded to the other surface of the ceramic substrate.

4. The multilayer bonded body according to claim 3, characterized in that: Also available: a third intermediate metal layer bonded to the surface of the second aluminum plate on the side opposite to the ceramic substrate and comprising any one of copper, nickel, silver and gold; a second copper sintered layer bonded to a surface of the third intermediate metal layer on the side opposite to the second aluminum plate; and The second metal member is bonded to a surface of the second copper sintered layer on the opposite side to the second aluminum plate, and includes any one of aluminum, aluminum alloy, copper, and copper alloy.

5. The multilayer bonded body according to claim 4, characterized in that: The second metal component comprises aluminum or an aluminum alloy, A fourth intermediate metal layer including any one of copper, nickel, silver, and gold is formed between the second metal member and the second copper sintered layer.

6. A semiconductor device, characterized in that: The multilayer bonded body according to claim 3 is used, and comprises: an electronic component mounted on a surface of the first metal member on the side opposite to the first copper sintered layer; A lead frame connected to the electronic component; and The insulating resin seals the electronic component in a state where the front end portion of the lead frame and at least the surface of the second aluminum plate on the side opposite to the ceramic substrate are exposed.

7. A semiconductor device, characterized in that: The multilayer bonded body according to claim 3 is used, and comprises: An electronic component is mounted on a surface of the second aluminum plate on the side opposite to the ceramic substrate; A lead frame connected to the electronic component; and The insulating resin seals the electronic component in a state where the front end portion of the lead frame and at least a surface of the first metal member other than a bonding surface with the first copper sintered layer are exposed.

8. A semiconductor device, characterized in that: The multilayer bonded body according to claim 4 is used, and comprises: an electronic component mounted on a surface of the first metal member on the side opposite to the first copper sintered layer; A lead frame connected to the electronic component; and The insulating resin seals the electronic component in a state where the front end portion of the lead frame and at least a surface of the second metal member other than a bonding surface with the second copper sintered layer are exposed.

9. A method for manufacturing a multilayer bonded body, characterized in that: include: A first lamination step of laminating a brazing material and a first aluminum plate made of aluminum or an aluminum alloy on one surface of a ceramic substrate to form a first laminate; a first bonding step of bonding the first stacked bodies by applying pressure and heating in a stacked state to form a first bonded body; an intermediate metal layer forming step of forming a first intermediate metal layer including any one of copper, nickel, silver and gold on a surface of the first aluminum plate in the first bonded body on the side opposite to the ceramic substrate; a second lamination step of laminating a first bonding material formed into a sheet shape by connecting a plurality of copper particles with an adhesive and a first metal member including any one of aluminum, aluminum alloy, copper and copper alloy in sequence on the first intermediate metal layer to form a second laminate; and In the second bonding step, the second stack is heated while being pressurized in a stacking direction to sinter the first bonding material to form a first copper sintered layer, and the first intermediate metal layer and the first metal member are bonded via the first copper sintered layer.

10. The method for producing a multilayer bonded body according to claim 9, wherein: The first metal component comprises aluminum or an aluminum alloy, In the intermediate metal layer forming step, a second intermediate metal layer including any one of copper, nickel, silver and gold is further formed on one surface of the first metal member. In the second bonding step, the second intermediate metal layer is bonded to the first copper sintered layer.

11. The method for producing a multilayer bonded body according to claim 9, wherein: Before the first lamination step, a plurality of grooves are formed on a surface of the first aluminum plate on the side opposite to the ceramic substrate.

12. The method for producing a multilayered bonded body according to any one of claims 9 to 11, characterized in that: In the first lamination step, a brazing material and a second aluminum plate made of aluminum or an aluminum alloy are further laminated on the other surface of the ceramic substrate to form the first laminated body. In the first bonding step, the first laminate including the second aluminum plate is pressurized and heated to form the first bonded body by bonding the first aluminum plate to one surface of the ceramic substrate and bonding the second aluminum plate to the other surface of the ceramic substrate.

13. The method for producing a multilayered bonded body according to claim 12, wherein: In the intermediate metal layer forming step, a third intermediate metal layer including any one of copper, nickel, silver and gold is further formed on the surface of the second aluminum plate in the first bonded body on the side opposite to the ceramic substrate. In the second lamination step, a second bonding material formed into a sheet by connecting a plurality of copper particles with an adhesive and a second metal member including any one of aluminum, aluminum alloy, copper and copper alloy are further laminated in sequence on the third intermediate metal layer to form the second laminated body. In the second bonding step, the second bonding material is further sintered to form a second copper sintered layer, and the third intermediate metal layer and the second metal member are bonded via the second copper sintered layer.

14. The method for producing a multilayered bonded body according to claim 13, wherein: The second metal component comprises aluminum or an aluminum alloy, In the intermediate metal layer forming step, a fourth intermediate metal layer including any one of copper, nickel, silver and gold is further formed on one surface of the second metal member. In the second bonding step, the fourth intermediate metal layer is bonded to the second copper sintered layer.

15. A method for manufacturing a semiconductor device, characterized in that: A semiconductor device is manufactured using the method for manufacturing a multilayer bonded body according to claim 12, The method for manufacturing a semiconductor device further comprises, after the second bonding step: a mounting step of mounting an electronic component on the first metal member and connecting a lead frame to the electronic component; and The resin sealing step is to seal the electronic component with the insulating resin in a state where the front end portion of the lead frame and at least the surface of the second aluminum plate on the opposite side to the ceramic substrate are exposed from the insulating resin.

16. A method for manufacturing a semiconductor device, characterized in that: A semiconductor device is manufactured using the method for manufacturing a multilayer bonded body according to claim 12, The method for manufacturing a semiconductor device further includes, between the intermediate metal layer forming step and the second stacking step: A mounting step of mounting an electronic component on the second aluminum plate and connecting a lead frame to the electronic component; and The resin sealing step is to seal the electronic component with the insulating resin in a state where the front end portion of the lead frame and at least the surface of the first intermediate metal layer are exposed from the insulating resin.

17. A method for manufacturing a semiconductor device, characterized in that: A semiconductor device is manufactured using the method for manufacturing a multilayer bonded body according to claim 12, In the intermediate metal layer forming step, a third intermediate metal layer including any one of copper, nickel, silver and gold is further formed on the surface of the second aluminum plate in the first bonded body on the side opposite to the ceramic substrate. The method for manufacturing a semiconductor device further comprises, after the second bonding step: a mounting step of mounting an electronic component on the first metal member and connecting a lead frame to the electronic component; a resin sealing step of sealing the electronic component with an insulating resin in a state where the front end portion of the lead frame and at least the surface of the third intermediate metal layer are exposed from the insulating resin; a third lamination step of further laminating a second bonding material formed into a sheet by connecting a plurality of copper particles with an adhesive and a second metal member including any one of aluminum, aluminum alloy, copper and copper alloy in sequence on the third intermediate metal layer to form a third laminate; and In the third bonding step, the third stack is heated while being pressurized in the stacking direction to sinter the second bonding material to form a second copper sintered layer, and the third intermediate metal layer and the second metal member are bonded via the second copper sintered layer.

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