Semiconductor device and method for manufacturing a semiconductor device

Abstract

Semiconductor device (101, 102, 103) comprising: a metal structure (1c); a semiconductor element (3) bonded to the metal structure (1c); and an electrode terminal (4) extending with a width, wherein the electrode terminal (4) is branched into a plurality of branching parts (4a, 4b) in a width direction at one end side of its extension direction, of the plurality of branching parts (4a, 4b), a first branching part (4a) and a second branching part (4b) are each bonded to the metal structure (1c) via a bonding material (2b, 2c), the first branching part (4a) has a greater width than that of the second branching part (4b) and the bonding material (2b, 2c) between the second branching part (4b) and the metal structure (1c) is thinner than the bonding material (2b) between the first branching part (4a) and the metal structure (1c).

Description

BACKGROUND OF THE INVENTIONField of the invention

[0001] The present disclosure relates to a semiconductor device. Description of the background technology

[0002] Japanese Patent Application Laid-Open No. JP 2015-046416 A discloses a semiconductor device comprising a conductive part having semiconductor elements arranged on a substrate, a case accommodating the conductive part, and a lead terminal formed integrally with the case and directly connected to the semiconductor elements or the wiring of the substrate. SUMMARY

[0003] When bonding a metal structure on an insulating substrate and an electrode terminal, a sufficiently elevated temperature is required at the bonding points of both the metal structure and the electrode terminal. One problem has been that, during bonding, a gap formed between the metal structure and the electrode terminal can cause insufficient heat conduction between the metal structure and the electrode terminal and an insufficient temperature rise of one of them, which can result in poor bonding.

[0004] US 2008 / 0 142 571 A1 describes an electronic device comprising a pair of connectors whose parts are formed to be extended on both sides relative to one end of its body. The pair of connectors, both connected to one of the substrates, improves the connection strength between a lead frame connector and one of the substrates and ensures the reliability of the electrical connection between the lead frame connector and one of the substrates.

[0005] Document DE 11 2014 006 908 T5 relates to a semiconductor device having highly reliable bonding portions. This semiconductor device includes an insulating substrate on which a conductive pattern is formed, and an electrode terminal and a semiconductor element bonded to the conductive pattern 4b. The electrode terminal and the conductive pattern are bonded by ultrasonic bonding on a bonding surface. The ultrasonic bonding is performed at a plurality of locations.

[0006] An object of the present disclosure is to provide a semiconductor device that suppresses poor bonding between a metal pattern and an electrode terminal due to insufficient temperature rise at the time of bonding the metal pattern and the electrode terminal.

[0007] The object underlying the invention is achieved in a semiconductor device according to the invention with the features of claim 1, in a semiconductor device according to the invention with the features of claim 2, and in methods for producing a semiconductor device alternatively according to the invention with the features of claims 13 and 14. Advantageous further developments are the subject of the respective dependent claims.

[0008] The semiconductor module according to the first aspect of the present disclosure includes a metal structure, a semiconductor element bonded to the metal structure, and an electrode terminal extending in a width direction. The electrode terminal is branched into a plurality of branch parts in a width direction on one end side of its extending direction. A first branch part and a second branch part of the plurality of branches are respectively bonded to the metal structure via a bonding material. The first branch part has a larger width than that of the second branch part. The bonding material between the second branch part and the metal structure is thinner than the bonding material between the first branch part and the metal structure.

[0009] With the above configuration, a semiconductor device is provided that suppresses poor bonding between a metal pattern and an electrode terminal due to insufficient temperature rise at the time of bonding the metal pattern and the electrode terminal.

[0010] These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross-sectional view of a semiconductor device of Embodiments 1 to 3; Fig. 2 is a perspective view of a part of a main electrode terminal of Embodiment 1; Fig. 3A to 3D are diagrams illustrating a part of the main electrode terminal of Embodiment 1, which is represented by a three-panel or third-angle projection: Fig. 4 is a diagram illustrating a bonded state between a main electrode terminal and a metal pattern of the semiconductor device of Embodiment 1; Fig. 5 is a diagram illustrating a state in a process of bonding the main electrode terminal and the metal pattern of the semiconductor device of Embodiment 1; Fig. 6 is a diagram illustrating a bonded state between a main electrode terminal and the metal structure of the semiconductor device of Embodiment 2; Fig. 7 is a diagram illustrating a state in a process of bonding the main electrode terminal and the metal pattern of the semiconductor device of an embodiment 3; Fig. 8 is a diagram illustrating a bonded state between the main electrode terminal and the metal structure of the semiconductor device of Embodiment 3; and Fig. 9 is a flowchart of a manufacturing method of the semiconductor device of Embodiments 1 to 3. DESCRIPTION OF THE PREFERRED EMBODIMENTS<A. Ausführungsform 1><A-1. Konfiguration>

[0011] Fig. 1 is a cross-sectional view illustrating a semiconductor device 101 of an embodiment 1. As in Fig. 1, the semiconductor device 101 includes a base member 1, a bonding material 2a, bonding materials 2b, a semiconductor element 3, a main electrode terminal 4, metal wires 5, a housing 6, signal terminals 7, a sealing resin 8, and an adhesive 9.

[0012] The bonding material 2a is a bonding material that connects or bonds the semiconductor element 3 and a metal structure 1c.

[0013] The bonding materials 2b are bonding materials that bond metal structures 1c and the main electrode terminal 4.

[0014] The metal wires 5 are wires for wiring within the semiconductor device 101.

[0015] Although the signal terminals 7 are drawn as if they were in contact with the upper surface of the semiconductor element 3 Fig. 1 are in contact, the signal terminals 7, which are located in deeper inner parts in the drawing with respect to the sheet surface of the semiconductor element 3, are actually bonded to the metal structure 1c via the bonding material 2a.

[0016] The adhesive 9 is an adhesive that bonds the housing 6 and the base part 1.

[0017] The base part 1 includes a heat sink 1a, an insulating substrate 1b, and metal structures 1c. The heat sink 1a is disposed on one main surface of the insulating substrate 1b, and the metal structure 1c is disposed on the other main surface of the insulating substrate 1b. The metal structures 1c exhibit conductivity. The material of the metal structures 1c is, for example, copper or aluminum. The material of the insulating substrate 1b is, for example, a ceramic with high thermal conductivity, such as aluminum nitride (AlN) or silicon nitride (SiN). The material of the insulating substrate 1b can also be an insulating resin. The insulating substrate 1b desirably exhibits high thermal conductivity.

[0018] The semiconductor element 3 is, for example, a semiconductor element using a silicon semiconductor. The semiconductor element 3 may be a semiconductor element using a wide band gap semiconductor having a larger band gap than silicon. The wide band gap semiconductor is, for example, a semiconductor using SiC- or GaN-based material.

[0019] The semiconductor element 3 is, for example, a diode, a metal-oxide-semiconductor field-effect transistor (MOSFET), an insulated-gate bipolar transistor (IGBT) or a reverse-conducting insulated-gate bipolar transistor (RC-IGBT).

[0020] The semiconductor element 3 is bonded to the metal circuit structure 1c of the base part 1 by the bonding material 2a. Although Fig. 1 illustrates a case where a semiconductor element is bonded to the base member 1, the number of semiconductor elements bonded to the base member 1 is not limited to one, and a required number of semiconductor elements can be bonded to the base member 1 according to the application.

[0021] The bonding material 2a that bonds the semiconductor element 3 and the base member 1 is, for example, a solder. For the solder, there is, for example, a tin (Sn)-based solder; however, the material is not particularly limited thereto. Furthermore, a plate-shaped solder may be used as the bonding material 2a, or a paste-shaped solder may also be used therefor. In the description of the manufacturing method described later, a case where the semiconductor element 3 and the base member 1 are bonded using a plate-shaped solder will be described.

[0022] In an internal circuit of the semiconductor device 101, the semiconductor element 3 and the metal pattern 1c, the main electrode terminal 4 and the metal pattern 1c, and the signal terminals 7 and the metal pattern 1c are formed in a manner that the metal wires 5, the bonding material 2a, and the bonding material 2b electrically connect therebetween, respectively.

[0023] The main electrode terminal 4 is an electrode terminal for supplying a current controlled by the semiconductor element 3 from outside the semiconductor device 101 to the semiconductor element 3. Fig. 4 is a diagram illustrating a bonded state between the main electrode terminal 4 and the metal pattern 1c.

[0024] The signal terminals 7 are terminals for inputting a signal controlling the semiconductor element 3 from outside the semiconductor device 101 to the semiconductor element 3.

[0025] The material of the casing 6 is, for example, a resin. The material of the casing 6 preferably has a high softening point, which is a temperature at which the material begins to soften and deform, in order to prevent a problem caused when the temperature rises during operation of the semiconductor device 101. The material of the casing 6 is, for example, polyphenylene sulfide (PPS). However, the material of the casing 6 is not limited to PPS, and any material that does not undergo thermal deformation at the operating temperature of the semiconductor device 101 and has insulating properties can be used.

[0026] The sealing resin 8 is, for example, a silicone-based gel or an epoxy-based resin. <A-2. Herstellungsverfahren><A-2-1. Zusammenfassung des Herstellungsverfahrens>

[0027] Fig. 9 is a flowchart of a manufacturing method of the semiconductor device 101.

[0028] In step S1, first, the semiconductor element 3 is bonded to the base member 1 using the bonding material 2a. The bonding material 2a is, for example, a plate-shaped solder. The plate-shaped solder is installed or applied to the metal structure 1c. When paste-shaped solder is used as the bonding material 2a, the paste-shaped solder is printed on the metal structure 1c. In step S1, the plate-shaped solder as the bonding material 2a is heated to a temperature exceeding the melting point to melt it, and then cured to bond the base member 1 and the semiconductor element 3.

[0029] Next, in step S2, the case 6, to which the main electrode terminal 4 and the signal terminals 7 are fixed, is bonded to the base member 1. In step S2, in preparation for bonding the case 6 to the base member 1, the bonding material 2b is applied to the metal pattern 1c at the position where the main electrode terminal 4 is bonded and the position where the signal terminals 7 are bonded. The bonding material 2b is selected in consideration of the operating temperature of the semiconductor device. The bonding material 2b is, for example, a plate-shaped solder. Further, in preparation for bonding the case 6 to the base member 1, a silicone-based or epoxy-based adhesive 9 is applied to the lower surface of the case 6, which is the bonding surface with the heat radiation plate 1a.With the bonding material 2b applied to the metal structure 1c and the adhesive 9 applied to the lower surface of the case 6, the case 6, to which the main electrode terminal 4 and the signal terminals 7 are fixed, is pressed onto the base member 1 under application of a load. The case 6 and the heat sink 1a are fixed with screws or the like, and the state in which they are pressed against each other is maintained even in the later step S3.

[0030] In step S3, the main electrode terminal 4 and the signal terminals 7 are bonded to the metal pattern 1c of the base part 1 through the bonding material 2b, respectively. The details of the bonding of the main electrode terminal 4 and the metal pattern 1c in step S3 will be described later.

[0031] In step S4, the interior of the housing 6 is sealed with the sealing resin 8. Although the sealing resin 8 is, for example, a silicone gel or an epoxy resin, the sealing resin 8 is not limited thereto and may be a resin having a desired elastic modulus and heat resistance. <A-2-2. Besonderheiten des Schritts S3 im Herstellungsverfahren>

[0032] The details of bonding the main electrode terminal 4 and the metal pattern 1c in step S3 will be described.

[0033] First, the main electrode connection 4 is described.

[0034] Fig. 2 illustrates the state of the main electrode terminal 4 in Embodiment 1 before bonding to the metal structure 1c. The main electrode terminal 4 has a thickness of approximately 0.5 mm to 1.2 mm. Furthermore, the main electrode terminal 4 has a width and extends in the direction in which a current flows. The main electrode terminal 4 is formed of Cu or a material containing Cu.

[0035] In Fig. 3A to 3D, an example of the state of the main electrode terminal 4 in Embodiment 1 after bonding to the metal structure 1c is shown by means of a third-angle projection. Furthermore, in Fig. 3A to 3D, the state of the main electrode terminal 4 before bonding to the metal structure 1c is illustrated by the alternating long and short dashed line.

[0036] In Fig. 2 and 3A to 3D, only the close vicinity of the part of the main electrode terminal 4 to be bonded to the metal structure 1c is illustrated.

[0037] As in Fig. 2 and 3A to 3D, the bonding part of the main electrode terminal 4, which is the bonding part with the metal structure 1c, which is a part of one end side in the extension direction thereof, is branched in the width direction into a wide branch part 4a and a narrow branch part 4b. The wide branch part 4a and the narrow branch part 4b each have a bend 4c. However, the wide branch part 4a or the narrow branch part 4b having a bend means not only that there is a bend in the middle of the wide branch part 4a or the narrow branch part 4b, but also that there is a bend between the wide branch part 4a or the narrow branch part 4b and a trunk part 4c. The length between the bend 4c and a tip part 4d in the narrow branch part 4b is longer than, for example, the length between the bend 4c and a tip part 4d in the wide branch part 4a.Both the wide branch part 4a and the narrow branch part 4b are bonded to the metal structure 1c via the bonding material 2b at the part between the bend 4c and the tip part 4d, that is, on the side of the tip part 4d from the bend 4c.

[0038] In Fig. 3B, the plus-z direction represents the direction perpendicular to the metal structure 1c in the state of the main electrode terminal 4 after the main electrode terminal 4 and the metal structure 1c are bonded to each other. Fig. 3B, for the state of the main electrode terminal 4 before the main electrode terminal 4 and the metal structure 1c are bonded to each other, the plus-z direction represents the direction perpendicular to the metal structure 1c in the arrangement when the main electrode terminal 4 and the metal structure 1c are pressed against each other to bond the main electrode terminal 4 and the metal structure 1c. The metal structure 1c is bonded to the main electrode terminal 4 on the minus-z direction side. The plus-z direction side is also referred to as the upper side, and the minus-z direction side is also referred to as the lower side. The difference in position in the plus-z direction is also referred to as the height difference. As shown by the alternate long and short dashed line in Fig. 3B or Fig. 3C, in the state before bonding to the metal pattern 1c, a height difference W2 is provided between the bend 4c of the narrow branch portion 4b and the tip portion 4d of the narrow branch portion 4b, so that the tip portion 4d of the narrow branch portion 4b is located on the lower side or lower than the bend 4c of the narrow branch portion 4b. That is, when the main electrode terminal 4 and the metal pattern 1c are bonded to each other, the narrow branch portion 4b is arranged toward the metal pattern 1c in such a manner that the tip portion 4d of the narrow branch portion 4b is closer to the metal pattern 1c than the bent portion 4c of the narrow branch portion 4b by the height difference W2.

[0039] Before the main electrode terminal 4 and the metal structure 1c are bonded to each other, the height difference between the bend 4c of the wide branch part 4a and the tip part 4d of the wide branch part 4a is, for example, 1 / 10 or less of the height difference W2. Fig. 3A to 3D illustrate a case where there is no height difference between the bend 4c of the wide branch part 4a and the tip part 4d of the wide branch part 4a before the main electrode terminal 4 and the metal pattern 1c are bonded. Before bonding to the metal pattern 1c, the bend 4c of the wide branch part 4a has a larger degree of bending than that of the bend 4c of the narrow branch part 4b.

[0040] The height difference W2 is set, for example, in such a manner that when the main electrode terminal 4 is bonded to the metal structure 1c in step S3 and the narrow branch part 4b is pressed against the metal structure 1c, the height difference W2 is almost eliminated and the narrow branch part 4b becomes substantially parallel to the metal structure 1c. The height difference W2 is, for example, in the range of 50 µm or more and 150 µm or less, and is, for example, about 100 µm.The height difference between the tip part 4d of the narrow branch part 4b and the bend 4c of the narrow branch part 4b after the main electrode terminal 4 and the metal pattern 1c are bonded to each other is, for example, 1 / 10 or less of the height difference W2 between the tip part 4d of the narrow branch part 4b and the bend 4c of the narrow branch part 4b before the main electrode terminal 4 and the metal pattern 1c are bonded to each other.

[0041] To ensure that the bend 4c of the narrow branch portion 4b is deeper than the bend 4c of the wide branch portion 4a, a height difference W1 is provided between the bend 4c of the narrow branch portion 4b and the bend 4c of the wide branch portion 4a. The height difference W1 is, for example, in the range of 50 µm or more and 150 µm or less, and is, for example, 100 µm.

[0042] Before the main electrode terminal 4 and the metal structure 1c are bonded to each other, the tip part 4d of the narrow branch part 4b is lower than the wide branch part 4a by a height difference W3, which is a difference combined with the height difference W1 and the height difference W2. For example, the height difference W3 is in the range of 100 μm or more and 300 μm or less.

[0043] In the finished semiconductor device 101, the bonding material 2b between the narrow branch part 4b and the metal structure 1c is thinner than the bonding material 2b between the wide branch part 4a and the metal structure 1c. For example, the bonding material 2b between the narrow branch part 4b and the metal structure 1c is thinner throughout its entire area than the thinnest part of the bonding material 2b between the wide branch part 4a and the metal structure 1c.

[0044] In step S2, when the housing 6 with the integrated main electrode terminal 4 is brought close to the base part 1 to attach the housing 6 to the base part 1, as shown in Fig. 5, first, the tip part 4d of the narrow branch part 4b, the bonding material 2b applied to the metal structure 1c. In the Fig. In the state illustrated in Figure 5, the narrow branch portion 4b on the bend 4c side is not in contact with the bonding material 2b. Furthermore, the wide branch portion 4a is not in contact with the bonding material 2b.

[0045] If from Fig. 5, a load is further applied to the housing 6 and the housing 6 is moved to the specified position as shown in Fig. 4, the part closer to the tip part 4d side (i.e., the part bonded to the metal structure 1c) than the bend 4c of the narrow branch part 4b is pressed against the metal structure 1c; therefore, the bending degree of the bend 4c of the narrow branch part 4b becomes large. That is, the narrow branch part 4b is deformed so that the tip part 4d moves upward with respect to the bend 4c, and the bonding part of the narrow branch part 4b with the metal structure 1c is substantially parallel to the surface of the metal structure 1c. Further, the narrow branch part 4b is pressed against the metal structure 1c via the bonding material 2b in a state where the bonding part with the metal structure 1c is substantially parallel to the surface of the metal structure 1c.

[0046] The bonding between the main electrode terminal 4 and the metal structure 1c through the bonding material 2b is performed by heating and melting the bonding material 2b, and then lowering the temperature of the bonding material 2b to harden the bonding material 2b. In the reflow system, the bonding material 2b is heated by blowing hot air onto the semiconductor device 101 at this stage or by bringing a hot plate into contact with the semiconductor device 101. If there is a large distance between the main electrode terminal 4 and the metal structure 1c when the bonding material 2b is heated, the degree of temperature rise of the main electrode terminal 4 and the metal structure 1c is prone to differences due to the influence of the heat capacity of each component of the semiconductor device 101 and the positional relationship with the heating source.In particular, when a hot plate is used to heat the bonding material 2b, heating typically occurs only from one side of the semiconductor device 101; therefore, the large distance between the main electrode terminal 4 and the metal structure 1c makes the difference in the degree of temperature rise between the main electrode terminal 4 and the metal structure 1c even more pronounced. If the temperature rise of the main electrode terminal 4 or the metal structure 1c is insufficient, the quality of the bonding or contacting of the main electrode terminal 4 and the metal structure 1c via the bonding material 2b deteriorates.

[0047] When the distance between the main electrode terminal 4 and the metal pattern 1c is large at the time of bonding due to the effects of the accuracy in integrating the main electrode terminal 4 into the case 6, the assembly accuracy of the case 6 and the base 1, and the deformation due to heating during bonding and the like, the heat transfer between the main electrode terminal 4 and the metal pattern 1c is insufficient, resulting in an insufficient temperature rise of the main electrode terminal 4 or the metal pattern 1c.

[0048] In the semiconductor device 101 of Embodiment 1, in the main electrode terminal 4, the narrow branch part 4b at the position closer to the metal structure 1c than the wide branch part 4a is pressed against the metal structure 1c via the bonding material 2b. Therefore, good heat conduction is achieved between the main electrode terminal 4 and the metal structure 1c via the bonding material 2b, which leads to a reduction in the difference in the degree of temperature rise between the main electrode terminal 4 and the metal structure 1c. As a result, an insufficient temperature rise is less likely to occur, and poor bonding between the main electrode terminal 4 and the metal structure 1c via the bonding material 2b can be suppressed.In the finished semiconductor device 101, the achievement of these effects at the time of its manufacture can be confirmed by, for example, making the bend 4c of the narrow branch part 4b closer to the metal structure 1c than the bend 4c of the wide branch part 4a, or by making the bonding material 2b between the narrow branch part 4b and the metal structure 1c thinner than the bonding material 2b between the wide branch part 4a and the metal structure 1c. For example, the thickness of the bonding material 2b between the narrow branch part 4b and the metal structure 1c at the thickest part is less than half the thickness of the bonding material 2b between the wide branch part 4a and the metal structure 1c at the thinnest part.

[0049] In step S2, the narrow branch portion 4b is pressed against the metal pattern 1c via the bonding material 2b, so that the state of the narrow branch portion 4b, in which the narrow branch portion 4b is inclined to be closer to the metal pattern 1c on the tip portion 4d side, changes to a state substantially parallel to the metal pattern 1c. Even if the distance between the main electrode terminal 4 and the metal pattern 1c is set larger than expected due to assembly accuracy, deformation due to heating, or the like at the time of manufacturing, the tip portion 4d of the narrow branch portion 4b is close to the metal pattern 1c due to the configuration in which the main electrode terminal 4 is provided with the height difference W2 before bonding.In this case, in the completed semiconductor device 101, the tip part 4d of the narrow branch part 4b is closer to the metal structure 1c than the bend 4c of the narrow branch part 4b, and the tip part 4d of the narrow branch part 4b is closer to the metal structure 1c than the entire wide branch part 4a. That is, the bonding material 2b between the narrow branch part 4b and the metal structure 1c is thinner on the tip part 4d side in the narrow branch part 4b, and the bonding material 2b between the tip part 4d of the narrow branch part 4b and the metal structure 1c is thinner than the bonding material 2b between the wide branch part 4a and the metal structure 1c at its thinnest part. The tip part 4d of the narrow branch part 4b, which is close to the metal structure 1c, promotes heat conduction between the main electrode terminal 4 and the metal structure 1c via the bonding material 2 in step S3.As a result, an insufficient temperature rise is less likely to occur, and poor bonding between the main electrode terminal 4 and the metal pattern 1c via the bonding material 2b can be suppressed. This further alleviates the mounting accuracy requirements required for bonding the main electrode terminal 4 and the metal pattern 1c.

[0050] The bend 4c of the narrow branch part 4b is more susceptible to deformation than the bend 4c of the wide branch part 4a due to its narrow width. Therefore, when the narrow branch part 4b is pressed against the metal structure 1c via the bonding material 2b and the bending degree of the bend 4c of the narrow branch part 4b increases, the stress applied to individual components of the semiconductor device 101 is small, and damage to individual components of the semiconductor device 101 is unlikely to occur. That is, even if the height difference W2 is provided between the bend 4c of the narrow branch part 4b and the tip part 4d of the narrow branch part 4b, damage to individual components of the semiconductor device 101 is unlikely to occur during manufacturing.Furthermore, the wide branch part 4a is also bonded to the metal structure 1c; therefore, the bonding area required for excitation can be ensured. The narrower the narrow branch part 4b, the easier the narrow branch part 4b is to deform. The width of the narrow branch part 4b is, for example, 1 / 4 or less of the width of the wide branch part 4a. The wider the narrow branch part 4b, the better the heat conduction between the narrow branch part 4b and the metal structure 1c. The width of the narrow branch part 4b is, for example, 1 / 5 or more of the width of the wide branch part 4a. The width of the narrow branch part 4b is, for example, 1 / 5 or more and 1 / 4 or less of the width of the wide branch part 4a.

[0051] The fact that both the height difference W1 and the height difference W2 are provided on the main electrode terminal 4 before bonding to the metal structure 1c prevents the wide branch part 4a from hindering the deformation of the narrow branch part 4b when the main electrode terminal 4 is pressed against the metal structure 1c. Therefore, the effect of alleviating the assembly accuracy conditions required for bonding the main electrode terminal 4 and the metal structure 1c to each other is more secure, which is achieved with the configuration in which the height difference W2 is provided on the narrow branch part 4b before bonding and the narrow branch part 4b is deformed at the time of bonding.

[0052] The semiconductor device 101 may include a plurality of electrode terminals. As the number of electrode terminals included in the semiconductor device 101 increases, the effect of the variation in temperature rise at the time the electrode terminals and the metal pattern are bonded to each other on the quality of the semiconductor device 101 becomes greater. Therefore, by using the main electrode terminals 4 having the structure described in Embodiment 1 for each of the plurality of electrode terminals included in the semiconductor device 101, a greater effect of quality improvement can be achieved. However, the main electrode terminal 4 described in Embodiment 1 can be used for only a limited part of the plurality of electrode terminals included in the semiconductor device 101. <B. Ausführungsform 2><B-1. Konfiguration>

[0053] Fig. 1 is a cross-sectional view illustrating a semiconductor device 102 of an embodiment 2. Fig. 6 is a diagram illustrating a bonded state between the main electrode terminal 4 and the metal structure 1c of the semiconductor device 102. The main electrode terminal 4 included in the semiconductor device 102 differs from the main electrode terminal 4 included in the semiconductor device 101 in that the bonding part to the metal structure 1c, which is a part on one end side of the main electrode terminal 4 in the extension direction, is branched in a different manner. The semiconductor device 102 is otherwise similar to the semiconductor device 101 of Embodiment 1.

[0054] As in Fig. 6, in the semiconductor device 102, the bonding part to the metal structure 1c, which is a part on one end side of the main electrode terminal 4 in the extension direction, is branched into three branch parts including a wide branch part 4a and two narrow branch parts 4b arranged on both sides thereof in the width direction. The wide branch part 4a and the two narrow branch parts 4b each have a bend 4c. The width of each of the two narrow branch parts 4b is, for example, 1 / 4 or less of the width of the wide branch part 4a. The width of each of the two narrow branch parts 4b is, for example, 1 / 5 or more of the width of the wide branch part 4a. The width of each of the two narrow branch parts 4b is, for example, 1 / 5 or more and 1 / 4 or less of the width of the wide branch part 4a.

[0055] Before bonding to the metal structure 1c, each of the two narrow branch parts 4b is provided with a height difference similar to the height difference W2 described in Embodiment 1. That is, in each of the two narrow branch parts 4b, the tip part 4d is located lower than the bend 4c. The height difference is, for example, in the range of 50 µm or more and 150 µm or less, and is, for example, about 100 µm. The height difference may or may not be the same for the two narrow branches 4b.

[0056] In order to make the respective bends 4c of the two narrow branch parts 4b deeper than the bend 4c of the wide branch part 4a, a height difference similar to the height difference W1 described in Embodiment 1 is provided between each of the bends 4c of the two narrow branch parts 4b and the bend 4c of the wide branch part 4a. The height difference is, for example, in the range of 50 µm or more and 150 µm or less, and is, for example, about 100 µm. The height difference may or may not be the same for the two narrow branches 4b. <B-2. Herstellungsverfahren>

[0057] The manufacturing method of the semiconductor device 102 of Embodiment 2 is the same as the manufacturing method of the semiconductor device 101 described in Embodiment 1, except for the point that the shape of the main electrode terminal 4 used therein is different.

[0058] In Embodiment 2, in each of the two narrow branch parts 4b, the tip part 4d is located lower than the bend 4c. Accordingly, in step S2, when the housing 6 with the integrated main electrode terminal 4 is brought close to the base part 1 to attach the housing 6 to the base part 1, the tip parts 4d of the two narrow branch parts 4b first contact the metal structure 1c.

[0059] From this state, when a load is further applied to the housing 6 and the housing 6 is pressed down to the specified position, the sides of the tip part 4d are pressed against the metal structure 1c by the bends 4c of the two narrow branch parts 4b (i.e., the parts bonded to the metal structure 1c), so that the degree of bending of the bends 4c of the two narrow branch parts 4b increases. That is, each of the two narrow branch parts 4b is deformed so that the tip part 4d moves upward with respect to the bend 4c, and the bonding parts of the two narrow branch parts 4b with the metal structure 1c are substantially parallel to the surface of the metal structure 1c. Further, the two narrow branch parts 4b are pressed against the metal structure 1c via the bonding material 2b in a state where the bonding parts with the metal structure 1c are substantially parallel to the surface of the metal structure 1c.

[0060] When the distance between the main electrode terminal 4 and the metal pattern 1c at the time of bonding becomes larger than expected due to the mounting accuracy or deformation by heating at the time of manufacturing or the like, in the bonding material 2b between each of the two narrow branch parts 4b and the metal pattern 1c, the bonding material 2b is thinner on the side of the tip part 4d of the narrow branch part 4b.

[0061] In the finished semiconductor device 102, in the bonding material 2b, the portions between the two narrow branch portions 4b and the metal structure 1c are thinner than the bonding material 2b between the wide branch portion 4a and the metal structure 1c. For example, in the bonding material 2b, the portions between the two narrow branch portions 4b and the metal structure 1c are each thinner throughout their entire area than the thinnest portion of the bonding material 2b between the wide branch portion 4a and the metal structure 1c.

[0062] Furthermore, in the completed semiconductor device 102, the bends 4c of the two narrow branching parts 4b are each closer to the metal structure 1c than the bend 4c of the wide branching part 4a.

[0063] In the semiconductor device 102, with the respective two narrow branch parts 4b, an effect similar to that achieved by the narrow branch part 4b described in Embodiment 1 is achieved. Further, in Embodiment 2, narrow branch parts 4b are arranged on both sides of the wide branch part 4a in the width direction; therefore, the variation in the width direction of the main electrode terminal 4 in the degree of temperature rise of the main electrode terminal 4 or the metal pattern 1c in step S3 is reduced. As a result, an insufficient temperature rise is less likely to occur, and the quality of bonding between the metal pattern 1c and the main electrode terminal 4 by the bonding material 2b improves. <C. Ausführungsform 3>

[0064] Fig. 1 is a cross-sectional view illustrating a semiconductor device 103 of an embodiment 3. Fig. 8 is a diagram illustrating a bonded state between the main electrode terminal 4 and the metal pattern 1c of the semiconductor device 103. In comparison, the semiconductor device 103 differs from the semiconductor device 101 of Embodiment 1 in that a part 1cb of the metal pattern 1c to which the narrow branch portion 4b is bonded is not connected to a part 1ca of the metal pattern 1c to which the wide branch portion 4a is bonded. Further, in the semiconductor device 103, the wide branch portion 4a and the part 1ca of the metal pattern 1c are bonded by the bonding material 2b, and the narrow branch portion 4b and the part 1cb of the metal pattern 1c are bonded by the bonding material 2c. The semiconductor device 103 is otherwise similar to the semiconductor device 101.Furthermore, the manufacturing method of the semiconductor device 103 is the same as the manufacturing method of the semiconductor device 101 described in Embodiment 1, except that the part 1ca and the part 1cb of the metal structure 1c are not connected, and the narrow branch part 4b and the part 1cb of the metal structure 1c are bonded by the bonding material 2c. The material of the bonding material 2c is, for example, the same as the material of the bonding material 2b.

[0065] Fig. Fig. 7 is a diagram illustrating a state in the middle of pressing the housing 6, to which the main electrode terminal 4 is fixed, against the base member 1 in step S2. In the Fig.In the state illustrated in FIG. 7, the tip side 4d of the narrow branch portion 4b is in contact with the portion 1cb of the metal structure 1c, and the bend side 4c of the narrow branch portion 4b is not in contact with the portion 1cb of the metal structure 1c. Furthermore, the wide branch portion 4a is not in contact with the portion 1ca of the metal structure 1c.

[0066] The semiconductor device 103 has two effects. One of the effects is an effect related to the bonding of the main electrode terminal 4 and the metal pattern 1c, which is the same effect as described in Embodiment 1. Another effect relates to heat radiation during operation of the semiconductor element 3. Hereinafter, the effect related to heat radiation during operation of the semiconductor element 3 will be described.

[0067] During operation of the semiconductor element 3, the semiconductor element 3 generates heat due to loss in the energized state. Furthermore, during operation of the semiconductor element 3, the current controlled by the semiconductor element 3 flows through the main electrode terminal 4, and Joule heat is generated at the main electrode terminal 4 due to the resistance of the main electrode terminal 4. The heat generated by the semiconductor element 3 and the main electrode terminal 4 is predominantly transferred to the heat sink 1a via the metal structure 1c and the insulating substrate 1b. As the current controlled by the semiconductor element 3 increases, the Joule heat generated at the main electrode terminal 4 also increases, and the degree of temperature rise of the main electrode terminal 4 also increases.

[0068] As the temperature of the main electrode terminal 4 rises, the heat transferred from the high-temperature main electrode terminal 4 to the metal structure 1c increases, and the temperature of the metal structure 1c rises. As a result, the temperature of the semiconductor element 3 mounted on the metal structure 1c rises.

[0069] In the semiconductor device 103, the part 1cb of the metal structure 1c to which the narrow branch part 4b is bonded and the part 1ca of the metal structure 1c to which the wide branch part 4a and the semiconductor element 3 are bonded are not connected; therefore, during the operation of the semiconductor element 3, no current flows through the narrow branch part 4b, and Joule heat is not generated in the narrow branch part 4b.

[0070] Part of the Joule heat generated at the main electrode terminal 4 during operation of the semiconductor element 3 is transferred to the heat sink 1a via the part 1cb of the metal structure 1c to which the narrow branch part 4b is bonded and the insulating substrate 1b. Part of the Joule heat generated in the main electrode terminal 4 is transferred to the heat sink 1a without passing through the part 1ca of the metal structure 1c on which the semiconductor element 3 is mounted, so that the temperature rise of the semiconductor element 3 can be suppressed. Therefore, a larger current can be controlled with the semiconductor device 103.

[0071] Also, a modification may be adopted in which, in a combination of Embodiment 2 and Embodiment 3, the two narrow branch parts 4b are bonded to the parts not connected to the part of the metal structure 1c on which the semiconductor element 3 is mounted, respectively, in the configuration of the semiconductor device 102 of Embodiment 2.

Claims

[1] A semiconductor device (101, 102, 103) comprising: a metal structure (1c); a semiconductor element (3) bonded to the metal structure (1c); and an electrode terminal (4) extending with a width, wherein the electrode terminal (4) is branched into a plurality of branching parts (4a, 4b) in a width direction at one end side of its extension direction, of the plurality of branching parts (4a, 4b), a first branching part (4a) and a second branching part (4b) are each bonded to the metal structure (1c) via a bonding material (2b, 2c), the first branching part (4a) has a greater width than that of the second branching part (4b) and the bonding material (2b, 2c) between the second branching part (4b) and the metal structure (1c) is thinner than the bonding material (2b) between the first branching part (4a) and the metal structure (1c). [2] A semiconductor device (101, 102, 103) comprising: a metal structure (1c); a semiconductor element (3) bonded to the metal structure (1c); and an electrode terminal (4) extending with a width, wherein the electrode terminal (4) is branched into a plurality of branching parts (4a, 4b) in a width direction at one end side of its extension direction, of the plurality of branching parts (4a, 4b), both the first branching part (4a) and the second branching part (4b) have a bend (4c), both the first branching part (4a) and the second branching part (4b) are bonded to the metal structure (1c) on one side of a tip part (4d) from the bend (4c) via a bonding material (2b, 2c), the first branching part (4a) has a greater width than that of the second branching part (4b) and the bend (4c) of the second branching part (4b) is closer to the metal structure (1c) than the bend (4c) of the first branching part (4a). [3] The semiconductor device (101, 102, 103) according to claim 1 or 2, wherein a width of the second branching part (4b) is 1 / 4 or less of a width of the first branching part (4a). [4] The semiconductor device (101, 102, 103) according to any one of claims 1 to 3, wherein the width of the second branching part (4b) is 1 / 5 or more of the width of the first branching part (4a). [5] The semiconductor device (101, 102, 103) according to any one of claims 1 to 4, wherein in the bonding material (2b, 2c) between the second branch part (4b) and the metal structure (1c), a thickness therein is thinner on the side of the tip part (4d) of the second branch part (4b). [6] The semiconductor device (103) according to any one of claims 1 to 5, wherein in the metal structure (1c), a part to which the first branch part (4a) is bonded and a part to which the second branch part (4b) is bonded are not connected to each other. [7] A semiconductor device (102) according to claim 1, wherein the electrode terminal (4) is branched into the first branching part (4a), the second branching part (4b) and a third branching part (4b) as a plurality of branching parts (4a, 4b) in a width direction on one end side of its extension direction, the first branching part (4a) has a greater width than that of the third branching part (4b), the second branching part (4b) is located on one side in the width direction of the first branching part (4a) and the third branching part (4b) is located on the other side in the width direction of the first branching part (4a), and the bonding material (2b, 2c) between the third branching part (4b) and the metal structure (1c) is thinner than the bonding material (2b) between the first branching part (4a) and the metal structure (1c). [8] A semiconductor device (103) according to claim 2, wherein the electrode terminal (4) is branched into the first branching part (4a), the second branching part (4b) and a third branching part (4b) as a plurality of branching parts (4a, 4b) in a width direction on one end side of its extension direction, the first branching part (4a) has a greater width than that of the third branching part (4b), the second branching part (4b) is located on one side in the width direction of the first branching part (4a) and the third branching part (4b) is located on the other side in the width direction of the first branching part (4a), the third branching part (4b) has a bend (4c), the third branching part (4b) on one side of the tip part (4d) is bonded from the bend (4c) via the bonding material (2b, 2c) to the metal structure (1c), and the bend (4c) of the third branching part (4b) is closer to the metal structure (1c) than the bend (4c) of the first branching part (4a). [9] A semiconductor device (103) according to claim 7 or 8, wherein a width of the second branching part (4b) is 1 / 4 or less of a width of the first branching part (4a) and a width of the third branching part (4b) is 1 / 4 or less of the width of the first branching part (4a). [10] Semiconductor device (103) according to one of claims 7 to 9, wherein a width of the second branching part (4b) is 1 / 5 or more of a width of the first branching part (4a) and the width of the third branching part (4b) is 1 / 5 or more of the width of the first branching part (4a). [11] Semiconductor device (103) according to one of claims 7 to 10, wherein in the bonding material (2b, 2c) between the second branching part (4b) and the metal structure (1c), a thickness therein is thinner on the side of the tip part (4d) of the second branching part (4b) and in the bonding material (2b, 2c) between the third branch part (4b) and the metal structure (1c), a thickness therein is thinner on a side of the tip part (4d) of the third branch part (4b). [12] Semiconductor device (103) according to one of claims 7 to 11, wherein in the metal structure (1c), a part to which the first branch part (4a) is bonded and a part to which the second branch part (4b) is bonded are not connected to each other and in the metal structure (1c), the part to which the first branch part (4a) is bonded and a part to which the third branch part (4b) is bonded are not connected to each other. [13] A method of manufacturing the semiconductor device (101, 102, 103) according to claim 1, wherein both the first branching part (4a) and the second branching part (4b) have a bend (4c), the method comprises bonding between the electrode terminal (4) and the metal structure (1c), which is carried out by heating and melting the bonding material (2b, 2c) and then curing the bonding material (2b, 2c), wherein, before the bonding between the electrode terminal (4) and the metal structure (1c) is performed, a degree of bending (4c) of the first branch part (4a) is set to be greater than a degree of bending (4c) of the second branch part (4b) and wherein, at a point where bonding is performed between the electrode terminal (4) and the metal structure (1c), the side of the tip part (4d) is pressed against the metal structure (1c) from the bend (4c) of the second branch part (4b), thereby increasing the degree of bending of the bend (4c) of the second branch part (4b). [14] A method of manufacturing the semiconductor device (101, 102, 103) according to claim 2, comprising bonding between the electrode terminal (4) and the metal structure (1c), which is carried out by heating and melting the bonding material (2b, 2c) and then curing the bonding material (2b, 2c), wherein, before the bonding between the electrode terminal (4) and the metal structure (1c) is performed, a degree of bending (4c) of the first branch part (4a) is set to be greater than a degree of bending (4c) of the second branch part (4b) and wherein, at a point where bonding is performed between the electrode terminal (4) and the metal structure (1c), the side of the tip part (4d) is pressed against the metal structure (1c) from the bend (4c) of the second branch part (4b), thereby increasing the degree of bending of the bend (4c) of the second branch part (4b).

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