Semiconductor device and method for manufacturing the same

Abstract

The purpose of the present invention is to provide techniques that make it possible to reduce attachment of a bonding member onto a specific electrode. This semiconductor device comprises: a semiconductor element having a surface on which a first electrode and a second electrode are provided; an insulating protection film provided on the surface of the semiconductor element and exposing the first electrode and the second electrode; a metal lead electrode bonded to the first electrode exposed from the protection film; and a bonding member bonding the first electrode exposed from the protection film with the metal lead electrode. The metal lead electrode includes an abutment portion that is a protrusion abutting on the protection film and providing a shield between the bonding member and the second electrode in a cross-sectional view.

Description

[Technical field]

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

[0002] In semiconductor devices such as power semiconductor devices, a configuration has been proposed in which a flat metal lead electrode is used instead of a metal wire bond in order to achieve a large current, a long life, and high reliability. However, in the manufacturing process of this configuration, in the process of melting the bonding material that bonds the metal lead electrode and the surface electrode of the semiconductor element, the bonding material may be scattered to the surroundings due to the volatilization of the activator contained in the bonding material or the emission of bubbles in the bonding material. In this case, the bonding material may adhere to the control electrode on the semiconductor element, making it difficult to wire bond the control electrode in the subsequent wiring process, resulting in a problem of deterioration in reliability and productivity.

[0003] In response to this, a semiconductor device has been proposed that includes a metal lead electrode that is joined to a main electrode via a joining member and has an electrical connection piece that is a protruding part (for example, Patent Document 1). According to this technology, the electrical connection piece can prevent the joining member from scattering, so that it is possible to prevent a decrease in the reliability of the semiconductor device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2019 / 167254 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since there is a gap below the electrical connection piece, there is still a problem that the joining material may fly off and adhere to electrodes such as the control electrode.

[0006] Therefore, the present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a technique capable of reducing adhesion of a bonding member to a specific electrode. [Means for solving the problem]

[0007] The semiconductor device according to the present disclosure comprises a semiconductor element having a surface on which a first electrode and a second electrode spaced apart from each other are provided, an insulating protective film provided on the surface of the semiconductor element and exposing the first electrode and the second electrode, a metal lead electrode joined to the first electrode exposed from the protective film, and a bonding member joining the first electrode exposed from the protective film and the metal lead electrode, wherein the metal lead electrode abuts the protective film and includes an abutment portion which is a convex portion that blocks the space between the bonding member and the second electrode in a cross-sectional view. Effect of the Invention

[0008] According to the present disclosure, the metal lead electrode includes a contact portion that is a protruding portion that contacts the protective film and blocks the space between the bonding member and the second electrode in a cross-sectional view. With this configuration, it is possible to reduce adhesion of the bonding member to a specific electrode.

[0009] The objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings. [Brief description of the drawings]

[0010] [Figure 1] 1 is a plan view showing a schematic configuration of a semiconductor device according to a first embodiment. [Diagram 2] 1 is a cross-sectional view of a portion of a semiconductor device according to a first embodiment. [Diagram 3] 1 is a plan view of a portion of a semiconductor device according to a first embodiment. [Figure 4] FIG. 2 is a cross-sectional view of a portion of a related semiconductor device. [Diagram 5] FIG. 11 is a cross-sectional view of a portion of a semiconductor device according to a second embodiment. [Figure 6] FIG. 11 is a cross-sectional view of a portion of a semiconductor device according to a third embodiment. [Figure 7] FIG. 11 is a plan view of a portion of a semiconductor device according to a third embodiment. [Figure 8] FIG. 11 is a cross-sectional view of a portion of a semiconductor device according to a fourth embodiment. [Figure 9] FIG. 13 is a cross-sectional view of a portion of a semiconductor device according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments will be described with reference to the accompanying drawings. The features described in each of the following embodiments are merely examples, and not all features are necessarily required. In addition, in the following description, similar components in multiple embodiments are given the same or similar reference numerals, and different components are mainly described. In addition, in the following description, specific positions and directions such as "upper", "lower", "left", "right", "front" or "back" do not necessarily correspond to positions and directions in actual implementation.

[0012] <Embodiment 1> FIG. 1 is a plan view showing a schematic configuration of a semiconductor device according to the first embodiment, FIG. 2 is a cross-sectional view taken along line A-A' in FIG. 1, and FIG. 3 is a plan view taken along line B-B' in FIG. 2.

[0013] The semiconductor device of the first embodiment comprises a base plate 1, a circuit board 2, bonding members 3a, 3b, and 3c, a semiconductor element 4, a protective film 5, a case 7, a metal lead electrode 8, an external signal terminal 9, a metal wire 10, and a sealing member (not shown).

[0014] The material of the base plate 1 is a material having excellent thermal conductivity, such as an aluminum alloy or copper.

[0015] The circuit board 2 in Fig. 2 includes circuit patterns 2a and 2c and an insulating layer 2b. The material of the insulating layer 2b is a ceramic with excellent thermal conductivity, such as aluminum nitride or silicon nitride, or a resin. The circuit pattern 2a is provided on the upper surface of the insulating layer 2b, and the circuit pattern 2c is provided on the lower surface of the insulating layer 2b. The material of the circuit patterns 2a and 2c is, for example, an aluminum alloy or copper, which has excellent thermal conductivity.

[0016] The bonding member 3c bonds the base plate 1 and the circuit pattern 2c. The bonding member 3b bonds the circuit pattern 2a of the circuit board 2 and the semiconductor element 4 mounted on the circuit board 2. The materials of the bonding members 3b and 3c and the bonding member 3a described later are, for example, solder or soft solder.

[0017] The surface electrode 4a, which is a first electrode, and the control electrode 4b, which is a second electrode, are spaced apart from each other, and the semiconductor element 4 has a surface on which the surface electrode 4a and the control electrode 4b are provided. The surface electrode 4a is a main electrode through which a relatively large current flows, and the control electrode 4b is an electrode for signal control of the semiconductor element 4. The material of the surface electrode 4a and the control electrode 4b is, for example, at least one of nickel (Ni) and gold (Au), and when the semiconductor element 4 has an Al (aluminum)-Si (silicon) layer, the surface electrode 4a and the control electrode 4b are provided on the Al-Si layer.

[0018] In the first embodiment, the semiconductor element 4 is an IGBT (Insulated Gate Bipolar Transistor), but is not limited thereto and may be, for example, a reverse conducting IGBT, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an SBD (Schottky Barrier Diode), or a PND (PN junction diode). The material of the semiconductor element 4 may be, for example, normal silicon (Si), or may be a wide band gap semiconductor such as silicon carbide (SiC), gallium nitride (GaN), or diamond. When the semiconductor element 4 is made of a wide band gap semiconductor, stable operation under high temperature and high voltage and high switching speed are possible. The number of semiconductor elements 4 is six in FIG. 1, but is not limited thereto and is determined according to the application of the semiconductor device.

[0019] 2 is provided on the surface of the semiconductor element 4 on which the surface electrode 4a and the control electrode 4b are provided, and exposes the surface electrode 4a and the control electrode 4b. The protective film 5 has insulating properties and is made of, for example, polyimide.

[0020] The bonding member 3a bonds the surface electrode 4a exposed from the protective film 5 to the metal lead electrode 8, and the metal lead electrode 8 is bonded to the surface electrode 4a exposed from the protective film 5. A portion of the metal lead electrode 8 facing the surface electrode 4a protrudes toward the surface electrode 4a, and this portion of the metal lead electrode 8 includes a contact portion 8a. The contact portion 8a is a convex portion that contacts the protective film 5 and blocks the gap between the bonding member 3a and the control electrode 4b in a cross-sectional view (see FIG. 2). The position of the bonding member 3a and the position of the surface electrode 4a are substantially the same, so the contact portion 8a substantially blocks the gap between the surface electrode 4a and the control electrode 4b in a cross-sectional view.

[0021] 3, a contact portion 8a is generally between the joining member 3a and the control electrode 4b. Although not shown, a part of the metal lead electrode 8 may be connected to the circuit pattern 2a of the circuit board 2 to form a circuit.

[0022] The case 7 in FIG. 1 includes an external electrode 7a and a case resin part 7b. The external electrode 7a is electrically connected to a metal lead electrode 8. The metal lead electrode 8 may be a part of the external electrode 7a or may be a different member from the external electrode 7a. When the metal lead electrode 8 is a part of the external electrode 7a, the metal lead electrode 8 may be formed by extending the external electrode 7a, which is inserted in advance into the case resin part 7b, onto the semiconductor element 4. When the metal lead electrode 8 is a different member from the external electrode 7a, the metal lead electrode 8 may be joined to the external electrode 7a, which is inserted in advance into the case resin part 7b, by soldering, welding, ultrasonic bonding, or the like.

[0023] The case resin part 7b encloses the semiconductor element 4, the metal lead electrodes 8, and the space surrounding them, and a sealing member (not shown) is provided in the space. A part of the external electrode 7a is exposed from the case resin part 7b outside the space, and an external device connected to a part of the external side of the external electrode 7a is electrically connected to the semiconductor element 4 via the external electrode 7a and the metal lead electrodes 8. The material of the sealing member is, for example, resin.

[0024] The external signal terminal 9 is provided in the case resin part 7b in the same manner as the external electrode 7a. The external signal terminal 9 constitutes a signal circuit by being electrically connected to the control electrode 4b by a metal wire 10. The metal wire 10 is made of a metal material having high thermal conductivity and electrical conductivity, such as aluminum.

[0025] <Manufacturing method> Next, an example of a method for manufacturing the semiconductor device according to the first embodiment will be described.

[0026] <Step S1> In the process of forming the semiconductor element 4, the surface electrode 4a and the control electrode 4b are formed on the semiconductor element 4. Thereafter, a protective film 5 for protecting the Al-Si layer is formed on the Al-Si layer of the semiconductor element 4, excluding the surface electrode 4a and the control electrode 4b. Since the surface electrode 4a and the control electrode 4b are metal-bonded or ultrasonically bonded in a later process, the protective film 5 made of polyimide or the like is not formed on the surface electrode 4a and the control electrode 4b. Note that the portion of the protective film 5 that will come into contact with the contact portion 8a of the metal lead electrode 8 in a later process may be thicker than the other portions.

[0027] <Step S2> The base plate 1, the circuit board 2, and the semiconductor element 4 are joined by joining members 3b, 3c such as plate solder, solder paste, soft solder, etc. Generally, solder is often used for the joining members 3b, 3c. The joining in step S2 is performed by heating the joining members 3b, 3c such as solder to a temperature exceeding their melting points. The joining members 3b, 3c may be preformed members such as plate solder, or may be members such as solder paste that are applied by screen printing, dispensing, or the like.

[0028] <Step S3> The case 7 is joined to the base plate 1. For example, a silicone-based or epoxy-based adhesive (not shown) is applied to the joining surface of the lower part of the case resin part 7b with the base plate 1, and then a load is applied to the base plate 1 on which the semiconductor element 4 is mounted in step S2, so that the case resin part 7b and the base plate 1 are closely attached and joined. Note that the fixing of the case 7 and the base plate 1 is not limited to this, and for example, the case resin part 7b and the base plate 1 may be fastened with a tapping screw (not shown) or the like, or may be fixed by heating the adhesive after being fixed with a clamp jig or the like.

[0029] <Step S4> A metal lead electrode 8 is disposed on the semiconductor element 4, and the surface electrode 4a and the metal lead electrode 8 are joined. Before this joining, the abutting portion 8a of the metal lead electrode 8 is first disposed in a state of abutting against the protective film 5 on the surface of the semiconductor element 4. This abutting portion 8a separates the joining member 3a from the control electrode 4b. The convex portion of the abutting portion 8a may be formed, for example, by pressing in the process of forming the metal lead electrode 8, or may be formed by bending as in the second embodiment.

[0030] In parallel with the abutment of the abutting portion 8a with the protective film 5, a bonding member 3a for bonding the surface electrode 4a of the semiconductor element 4 and the metal lead electrode 8 is supplied. The bonding member 3a may be supplied by dispense application or screen printing onto the surface electrode 4a of the semiconductor element 4 before the metal lead electrode 8 is disposed on the semiconductor element 4. Alternatively, as in the fourth and fifth embodiments, the bonding member 3a may be supplied from a through hole provided in advance in the metal lead electrode 8 after the metal lead electrode 8 is disposed on the semiconductor element 4. Alternatively, the bonding member 3a may be supplied as pre-solder onto the surface electrode 4a of the semiconductor element 4 by dispense application or screen printing during step S2.

[0031] After the metal lead electrodes 8 are arranged and the bonding members 3a are supplied, the bonding members 3a are heated to a temperature exceeding their melting point, as in step S2, to bond the surface electrodes 4a of the semiconductor element 4 to the metal lead electrodes 8. The melting point of the bonding members 3a is preferably lower than that of the bonding members 3b, but may be the same.

[0032] <Step S5> To electrically connect to a signal circuit for controlling the semiconductor element 4, the control electrode 4b on the semiconductor element 4 and an external signal terminal 9 are wire-bonded with a metal wire 10. For example, ultrasonic bonding is used for the wire bonding.

[0033] <Step S6> In the structure assembled in steps S1 to S5, the space surrounded by the case resin portion 7b is sealed with a sealing member (not shown). The material of the sealing member is, for example, silicone gel or epoxy resin, but is not limited thereto, and any material having desired physical properties such as elastic modulus, heat resistance, adhesiveness, and linear expansion coefficient may be used. The assembled structure is placed in a curing oven or the like to perform necessary curing of the sealing member, thereby completing the semiconductor device. Thereafter, the semiconductor device is inspected for necessary electrical characteristics, etc.

[0034] <Summary of the first embodiment> Fig. 4 is a cross-sectional view showing the configuration of a semiconductor device related to the semiconductor device according to the first embodiment (hereinafter referred to as "related semiconductor device"), and corresponds to Fig. 2. In step S4 of melting the bonding members 3a, a part of the bonding members 3a may scatter due to volatilization of an activating component in the bonding members 3a (e.g., flux in a paste solder) or expulsion of air bubbles in the bonding members 3a.

[0035] In the related semiconductor device, since the contact portion 8a according to the present embodiment 1 is not provided, a part of the scattered bonding member 3a may adhere to the control electrode 4b. As a result, it becomes difficult to wire bond the control electrode 4b in the wiring process of step S5, and there is a problem that the reliability and productivity are deteriorated.

[0036] In contrast, in the present embodiment 1, the contact portion 8a blocks the gap between the bonding member 3a and the control electrode 4b in a cross-sectional view, so that the adhesion of the bonding member 3a to the control electrode 4b can be reduced. As a result, it is expected that a semiconductor device with a long life can be stably manufactured.

[0037] <Embodiment 2> Fig. 5 is a cross-sectional view showing the configuration of a semiconductor device according to the second embodiment, and corresponds to Fig. 2. In the first embodiment, the abutment portion 8a is provided in the center in the in-plane direction of the metal lead electrode 8 as shown in Fig. 2. In the second embodiment, the abutment portion 8a is provided at the end (the right end in Fig. 5) in the in-plane direction of the metal lead electrode 8 as shown in Fig. 5. The other basic configuration is the same as that of the first embodiment.

[0038] According to the configuration of the present embodiment 2 as described above, it is possible to reduce adhesion of the bonding member 3a to the control electrode 4b, similarly to the embodiment 1. In addition, since the contact portion 8a can be formed by a relatively easy bending process, it is expected that the manufacturing cost can be reduced.

[0039] <Embodiment 3> Fig. 6 is a cross-sectional view showing the configuration of a semiconductor device according to a third embodiment, and corresponds to Fig. 2. Fig. 7 is a plan view taken along the line CC' in Fig. 6.

[0040] As shown in Fig. 6, in the third embodiment, the metal lead electrode 8 has a recess 8b in the lower part of the metal lead electrode 8. In the example of Fig. 6, the recess 8b has a dome shape, but the present invention is not limited to this.

[0041] A bonding member 3a is provided in the recess 8b, and in the example of Fig. 6, the recess 8b is filled with the bonding member 3a. The edge of the recess 8b abuts against the protective film 5, and includes the abutting portion 8a.

[0042] The edge of the recess 8b, indicated by the dotted line in the plan view of Fig. 3, surrounds the entire periphery of the joining member 3a in plan view, and the abutting portion 8a completely blocks the space between the joining member 3a and the control electrode 4b. A through hole may be provided that penetrates from the upper surface of the metal lead electrode 8 to the bottom surface of the recess 8b. The other basic configuration is the same as that of the first embodiment.

[0043] According to the configuration of the third embodiment as described above, it is possible to reduce adhesion of the bonding member 3a to the control electrode 4b, as in the first embodiment. In addition, since the edge of the recess 8b surrounds the entire circumference of the bonding member 3a, it is possible to reduce the bonding member 3a from scattering and adhering not only to the control electrode 4b but also to other locations (such as the circuit board 2 or other semiconductor elements 4). As a result, it is possible to suppress a decrease in insulation performance.

[0044] Furthermore, since the contact area between the metal lead electrode 8 and the bonding member 3a can be increased, the current density during use of the semiconductor device can be reduced, and deterioration of reliability due to localized heat generation can be suppressed.

[0045] <Fourth embodiment> FIG. 8 is a cross-sectional view showing the configuration of a semiconductor device according to the fourth embodiment, and corresponds to FIG.

[0046] As shown in FIG. 8, in the fourth embodiment, the metal lead electrode 8 has a through hole 8c in which a bonding member 3a is provided. The edge of the through hole 8c abuts against the protective film 5, and surrounds the entire circumference of the bonding member 3a in a plan view, similar to the edge of the recess 8b in the third embodiment. In a plan view, the through hole 8c may have a rectangular shape or a circular shape in accordance with the shape of the front electrode 4a of the semiconductor element 4. In a plan view, the area of ​​the through hole 8c may be equal to or larger than the area of ​​the front electrode 4a of the semiconductor element 4. The other basic configurations are the same as those of the first embodiment.

[0047] According to the configuration of the present embodiment 4 as described above, like the embodiment 3, it is possible to reduce adhesion of the bonding material 3a to the control electrode 4b and also to reduce adhesion to locations other than the control electrode 4b. Furthermore, since a relatively large through hole 8c can be provided in the metal lead electrode 8, the bonding material 3a can be supplied by dispense coating from the through hole 8c of the metal lead electrode 8 after the metal lead electrode 8 is placed on the semiconductor element 4. As a result, it is possible to easily supply the bonding material 3a.

[0048] Conventionally, non-destructive testing of the bond between the metal lead electrode 8 and the bonding member 3a may be performed using ultrasonic testing or X-rays. In contrast, in the fourth embodiment, the bond can be visually inspected based on whether the bonding member 3a has crawled up the wall surface of the through hole 8c of the metal lead electrode 8. This makes it possible to simplify the inspection of the bond, and it is expected that inspection using ultrasonic testing or X-rays will not be required.

[0049] <Embodiment 5> FIG. 9 is a cross-sectional view showing the configuration of a semiconductor device according to the fifth preferred embodiment, and corresponds to FIG.

[0050] 9, in the fifth embodiment, the metal lead electrode 8 has a plurality of through holes 8c in which the bonding members 3a are provided. The metal lead electrode 8 includes partition portions 8d that partition the plurality of through holes 8c and contact the bonding members 3a. The number, width, and height positions of the partition portions 8d are not important. The other basic configurations are the same as those of the fourth embodiment.

[0051] According to the configuration of the present embodiment 4 as described above, it is possible to reduce adhesion of the bonding members 3a to the control electrodes 4b and to reduce adhesion to locations other than the control electrodes 4b, similarly to the embodiment 3. Also, similarly to the embodiment 4, the through holes 8c can facilitate the supply of the bonding members 3a and simplify the inspection of the bonding property.

[0052] In addition, the partition 8d can increase the contact area between the metal lead electrode 8 and the bonding member 3a, thereby reducing the current density during use of the semiconductor device and suppressing deterioration in reliability due to localized heat generation. In addition, the partition 8d can reduce the amount of bonding member 3a used.

[0053] It should be noted that the embodiments and modifications may be freely combined, and the embodiments and modifications may be modified or omitted as appropriate.

[0054] The above description is illustrative in all respects and is not restrictive. It is understood that countless variations not illustrated can be envisioned. [Explanation of symbols]

[0055] 2 circuit board, 3a bonding member, 4 semiconductor element, 4a surface electrode, 4b control electrode, 5 protective film, 8 metal lead electrode, 8a contact portion, 8b recess, 8c through hole, 8d partition portion.

Claims

1. a semiconductor element having a surface on which a first electrode and a second electrode spaced apart from each other are provided; an insulating protective film provided on the surface of the semiconductor element, the protective film exposing the first electrode and the second electrode; a metal lead electrode joined to the first electrode exposed from the protective film; a bonding member that bonds the first electrode exposed from the protective film to the metal lead electrode; Equipped with The metal lead electrode is The semiconductor device includes a contact portion that is a protrusion that contacts the protective film and blocks a gap between the bonding member and the second electrode in a cross-sectional view.

2. 2. The semiconductor device according to claim 1, The semiconductor device further comprises a circuit board on which the semiconductor element is mounted and which is joined to a portion of the metal lead electrode.

3. 3. The semiconductor device according to claim 1, The contact portion is provided at an end portion in an in-plane direction of the metal lead electrode.

4. 3. The semiconductor device according to claim 1, the metal lead electrode has a recess in which the bonding member is provided, the edge of the recess abuts against the protective film, the abutting portion being included in the semiconductor device.

5. 3. The semiconductor device according to claim 1, the metal lead electrode has one or more through holes in which the bonding member is provided, The semiconductor device includes an edge portion of the through hole that abuts against the protective film and includes the abutment portion.

6. 6. The semiconductor device according to claim 5, the one or more through holes are a plurality of through holes, The metal lead electrode includes a partition portion that partitions the plurality of through holes and is in contact with the bonding member.

7. A method for manufacturing a semiconductor device according to any one of claims 1 to 6, comprising the steps of: a first electrode and a metal lead electrode are joined by the joining member by melting the joining member while the contact portion is in contact with the protective film.

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