Semiconductor device and method for manufacturing the same

Abstract

Semiconductor device comprising: • a base plate (1a); • a housing (1e) which surrounds a space on the base plate (1a); • a semiconductor element (2) arranged in the space; • a terminal electrode (3) connected to an upper surface of the semiconductor element (2) in the space; • a raised portion (4) arranged on an upper surface of the terminal electrode (3) in the space; • a sealing resin (5) which seals the semiconductor element (2) and the terminal electrode (3) in the space; • a through hole (3e), which is located next to the raised portion (4) in a plan view, is arranged in the terminal electrode (3); wherein • the connection electrode (3) has an end portion (3d) opposite a side wall of the housing (1e), and • the through hole (3e) is arranged between the end portion (3d) and a portion at which the raised portion (4) is provided in the terminal electrode (3).

Description

Background of the inventionField of the invention

[0001] The present invention relates to a semiconductor device and a method for manufacturing the same. Description of the state of the art

[0002] A semiconductor device is proposed which comprises a substrate, a semiconductor element arranged on the substrate, a terminal electrode connected to an upper surface of the semiconductor element, and a sealing resin which seals the substrate, the semiconductor element, and the terminal electrode in a space of a base plate and a housing (for example, WO 2019 / 194272).

[0003] Further conventional semiconductor devices are known from DE 11 2016 005 807 T5, DE 11 2016 006 928 T5, DE 11 2015 002 348 T5 and DE 11 2018 002 403 T5. Summary

[0004] Such a semiconductor device is manufactured by accommodating the substrate, the semiconductor element, and the terminal electrode in the space, and then injecting a flow resin, which is a sealing resin, into the space before curing. However, the gap between the terminal electrode and the base plate is narrow, resulting in a problem that a void is created that is not filled with the flow resin in a part of the gap. This void reduces the electrical insulation property and reliability of the semiconductor device.

[0005] The present disclosure has therefore been made to solve the above problem, and it is an object of the present disclosure to provide a technique capable of preventing occurrence of the unfilled portion.

[0006] This problem is solved by the features of the independent claims. The subclaims contain advantageous embodiments of the invention.

[0007] The occurrence of the unfilled section can be prevented by the invention.

[0008] 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. Short description of the characters Fig. 1 is a cross-sectional view illustrating a configuration of a semiconductor device according to an explanatory comparative example. Fig. 2 is a cross-sectional view for describing a method of manufacturing the semiconductor device according to Comparative Example. Fig. 3 is a cross-sectional view for describing a method of manufacturing a related semiconductor device. Fig. 4 is a cross-sectional view illustrating a configuration of a semiconductor device according to Embodiment 1. Fig. 5 is a cross-sectional view illustrating a configuration of a semiconductor device according to Embodiment 2.

[0009] Comparative examples are described below with reference to the accompanying figures. Features described in each embodiment are exemplary; therefore, not all features necessarily apply. The same or similar reference numerals are assigned to the same or similar components in a plurality of embodiments in the following description, and the different components are mainly described below. A specific position and direction, such as "upper side" or "lower side," do not necessarily correspond to a direction in an actual implementation of the following description. <Erläuterndes Vergleichsbeispiel>

[0010] Fig. 1 is a cross-sectional view illustrating a configuration of a semiconductor device according to the present comparative example. The semiconductor device in Fig. 1 comprises a base plate 1a, a housing 1e, a semiconductor element 2, connecting materials 2a and 2b, a terminal electrode 3, a raised portion 4, and a sealing resin 5.

[0011] The housing 1e surrounds a space on the base plate 1a. In the following description, a space defined by the base plate 1a and the housing 1e is referred to as "the housing space."

[0012] The base plate 1a includes a heat radiation plate 1b, which is made of, for example, a metal such as an aluminum alloy, an insulating substrate 1c, which is made of, for example, a ceramic such as aluminum nitride and silicon nitride and a resin, and a metal pattern 1d, which is made of, for example, a metal such as an aluminum alloy or copper. The heat radiation plate 1b functions as a heat radiator.

[0013] The housing 1e is formed of, for example, a resin such as polyphenylene sulfide (PPS). The housing 1e is bonded to a peripheral edge portion of the base plate 1a using, for example, a silicone resin.

[0014] The semiconductor element 2 is arranged in the housing space. The semiconductor element 2 may be a semiconductor switching element such as an insulated gate bipolar transistor (IGBT), a reverse conducting IGBT, a metal oxide semiconductor field-effect transistor (MOSFET), or it may be a diode such as a PN junction diode (PND) and a Schottky diode (SBD). A material of the semiconductor element 2 may be silicon (Si) or it may be a wide band-gap semiconductor such as silicon carbide (SiC), gallium nitride (GaN), or diamond, which has a wider band gap than silicon. When the semiconductor element 2 is formed of a wide band-gap semiconductor, stable operation under high temperature and high voltage and an increase in switching speed can be achieved.

[0015] In the example in Fig. 1, each of the two semiconductor elements 2 is connected to the metal pattern 1d by means of the bonding material 2a. The number of semiconductor elements 2 is not limited to two, but varies depending on the application. The material of the bonding material 2a is determined taking into account the operating temperature of the semiconductor device and is generally a solder.

[0016] The terminal electrode 3 is formed of metal, for example, and is connected to an upper surface of the semiconductor element 2 in the housing space. As described above, the terminal electrode 3 connects the semiconductor element 2 and an external electrode, rather than a metal wire connection, and is used for a main current path, thus achieving high current density and high reliability.

[0017] In the present example, the terminal electrode 3 has a first terminal electrode 3a and a second terminal electrode 3b, which are separated from each other. In the example in Fig. 1, the first terminal electrode 3a is connected to an upper surface of one semiconductor element 2 by means of the connecting material 2b, and the second terminal electrode 3b is connected to an upper surface of the other semiconductor element 2 by means of the connecting material 2b. A material of the connecting material 2b is determined taking into account an operating temperature of the semiconductor device and is generally a solder.

[0018] When the first terminal electrode 3a and the second terminal electrode 3b are not distinguished from each other, they are referred to as the terminal electrode 3 in the following description. The number of terminal electrodes 3 is not limited to two, but is changed according to use.

[0019] The terminal electrode 3 has an end portion 3c and an end portion 3d. The end portion 3c on the same side as the housing 1e is directly attached to the housing 1e. The end portion 3d opposite a side wall of the housing 1e is indirectly attached to the housing 1e. In the example in Fig. 1, an area of ​​an upper surface of the terminal electrode 3 is larger than an area of ​​a side surface of the terminal electrode 3.

[0020] The raised portion 4 is disposed on the upper surface of the terminal electrode 3 in the housing space, and protrudes toward an upper side of the upper surface of the terminal electrode 3. In the present example, the raised portion 4 includes a first raised portion 4a disposed on an upper surface of the first terminal electrode 3a on the second terminal electrode 3b side, and a second raised portion 4b disposed on an upper surface of the second terminal electrode 3b on the first terminal electrode 3a side.

[0021] When the first raised portion 4a and the second raised portion 4b are not distinguished from each other, they are referred to as the raised portion 4 in the following description. The number of raised portions 4 is not limited to two, that is, the number of each of the first raised portions 4a and the second raised portions 4b is not limited to one, but is changed according to use.

[0022] The raised portion 4 includes a resin-cured material 4c and an adhesive material 4d that adheres the resin-cured material 4c to the terminal electrode 3. Any shape is applicable as the shape of the resin-cured material 4c as long as the flow of a flow resin, which will be described below, can be controlled; thus, a rectangular shape or an arc-like shape is also applicable. For example, a height of the resin-cured material 4c may be substantially equal to or less than 10 mm.

[0023] The sealing resin 5 is made of epoxy, for example, and seals the semiconductor element 2 and the terminal electrode 3 in the housing space. The sealing resin 5 protects the insulating substrate 1c, the semiconductor element 2, and the terminal electrode 3 from the external environment. <herstellungsverfahren>

[0024] Next, a method for manufacturing the semiconductor device in Fig. 1 in sequence from a first procedure to a fifth procedure separately. <Erste Prozedur>

[0025] The base plate 1a and the semiconductor element 2 are connected by the bonding material 2a. For example, a plate solder as the bonding material 2a is placed on the metal pattern 1d, and the plate solder is heated to its melting point, thereby performing soldering to connect the semiconductor element 2 to the base plate 1a. For example, a paste solder as the bonding material 2a is printed on the metal pattern 1d, and the paste solder is heated to its melting point, thereby performing soldering to connect the semiconductor element 2 to the base plate 1a. <Zweite Prozedur>

[0026] The housing 1e integrated with the terminal electrode 3 is bonded to the base plate 1a to form the housing space. In parallel, a solder pad or solder paste, for example, is pre-applied to the semiconductor element 2 as the bonding material 2b, and a silicone-series or epoxy-series adhesive material (not shown in the figures) is pre-applied to a bonding surface between a lower portion of the housing 1e and the heat-radiating plate 1b.

[0027] In this state, a force is applied from one side of the base plate 1a and the housing 1e toward the other side, thereby firmly bonding the lower portion of the housing 1e and the heat-radiating plate 1b to make contact between the terminal electrode 3 and the bonding material 2b. Subsequently, a hardening heat treatment is performed to harden the bonding material between the lower portion of the housing 1e and the heat-radiating plate 1b. A self-tapping screw (not shown in the figure) can be used to screw the housing 1e and the heat-radiating plate 1b together instead of the bonding material. <Dritte Prozedur>

[0028] The semiconductor element 2 and the terminal electrode 3 are connected by means of the bonding material 2b. Heating for bonding the bonding material 2b can be performed simultaneously with the curing of the bonding material in the second procedure. <Vierte Prozedur

[0029] The adhesive material 4d is applied to a part of the upper surface of the terminal electrode 3, and the resin-cured material 4c is arranged on the adhesive material 4d to provide the raised portion 4 having a required shape on the upper surface of the terminal electrode 3. For the resin of the resin-cured material 4c, a resin is used that has a Young's modulus (for example, substantially 9 to 13 GPa), a desired heat resistance (for example, a maximum of 200°C), and a linear thermal expansion coefficient equal to that of the sealing resin 5. <Fünfte Prozedur>

[0030] As in Fig. As illustrated in Figure 2, a nozzle 8 of a resin sealing injection machine is arranged above the end portion 3d side of the raised portion 4. In the configuration assembled in the first to fourth procedures, a liquid flow resin 5a, which is the sealing resin 5, is discharged from the nozzle 8 to be injected into the package space. Accordingly, the semiconductor element 2 and the terminal electrode 3 are sealed by means of the flow resin 5a.

[0031] For example, a silicone gel or an epoxy resin is used as the sealing resin 5 and the flow resin 5a, but their materials are not limited thereto. Any resin can be used as long as it has physical properties such as elastic modulus (for example, substantially 0.1 to 10 MPa for silicone gel, and substantially 9 to 13 GPa for epoxy resin), desired heat resistance (for example, substantially 200°C maximum), adhesive properties, and a desired linear thermal expansion coefficient. The package can be pressureless when the flow resin 5a is injected into the package space.

[0032] The injected flow resin 5a is cured, for example, in a curing oven to be the sealing resin 5, and the semiconductor device in Fig. 1 is completed. An inspection, such as necessary electrical properties, is performed on the completed semiconductor device. <wirkung>

[0033] Before describing an effect in the present example, a semiconductor device related to the semiconductor device according to the present example (hereinafter referred to as "the related semiconductor device") will be described. Fig. 3 is a cross-sectional view for describing a method of manufacturing a related semiconductor device. The raised portion 4 is not provided in the related semiconductor device.

[0034] As in Fig. 3, in the configuration in which the terminal electrode 3 is connected to the upper surface of the semiconductor element 2, a gap between the terminal electrode 3 and the insulating substrate 1c or between the terminal electrode 3 and the semiconductor element 2 (hereinafter referred to as "the gap at the lower portion of the electrode") is small. Consequently, in the fifth procedure in which the flow resin 5a is injected, the upper surface of the terminal electrode 3 is covered by the flow resin 5a in many cases earlier than the gap at the lower portion of the electrode is filled with the flow resin 5a.

[0035] When the flow resin 5a flowing on the upper surface of the terminal electrode 3 and the flow resin 5a flowing in the gap at the lower portion of the electrode meet, a void 9 not filled with the flow resin 5a easily appears near a confluence of the flow resin 5a in the gap at the lower portion of the electrode. Consequently, there is a problem that the void 9 reduces electrical insulation properties and reliability in the related semiconductor device.

[0036] In contrast, according to the present example, the raised portion 4 is provided on the upper surface of the terminal electrode 3, whereby the raised portion 4 blocks the flow of the flow resin 5a flowing on the upper surface of the terminal electrode 3. Accordingly, the flow of the flow resin 5a in the gap at the lower portion of the electrode is relatively promoted, and the flow resin 5a fills the space around the terminal electrode 3 sequentially from a lower portion to an upper portion of the terminal electrode 3. As a result, the occurrence of an unfilled portion 9 in the gap at the lower portion of the electrode can be suppressed, and a reduction in an electrical insulation property and a reliability of the semiconductor device caused by the unfilled portion 9 can be suppressed.This configuration also exists in a case where a viscosity of the flow resin 5a is, for example, substantially equal to 100 Pa s, which is relatively high.

[0037] According to the present example, the raised portion 4 comprises a resin-cured material. According to such a configuration, the raised portion 4 can be formed from a general material. The shape, height, and size of the raised portion 4 can be easily changed, allowing the shape, height, and size of the raised portion 4 to be appropriately set in accordance with the shape and size of the semiconductor device, the nozzle position, and the injection speed of the flow resin 5a.

[0038] The configuration of the raised portion 4 is not limited to this, but, for example, a ribbon-shaped metal wire, a metal body, or a part of the terminal electrode 3 can also be used as the raised portion 4. When the part of the terminal electrode 3 is used for the raised portion 4, the number of components can be reduced.

[0039] In the present example, the first raised portion 4a is arranged on the upper surface of the first terminal electrode 3a on the second terminal electrode 3b side, and the second raised portion 4b is arranged on the upper surface of the second terminal electrode 3b on the first terminal electrode 3a side. According to such a configuration, the flow resin 5a is guided through the first raised portion 4a and the second raised portion 4b into the space between the first terminal electrode 3a and the second terminal electrode 3b, thus promoting the flow of the flow resin 5a into the gap at the lower portion of the electrode. As a result, the occurrence of an unfilled portion 9 in the gap at the lower portion of the electrode can be suppressed. <Ausführungsform 1>

[0040] Fig. 4 is a cross-sectional view illustrating a configuration of a semiconductor device according to the present embodiment 1. A configuration in the present embodiment 1 is similar to that in the comparative example, except that a through-hole 3e, which is located adjacent to the raised portion 4 in a plan view, is arranged in the terminal electrode 3. The state in which the through-hole 3e is located adjacent to the raised portion 4 in a plan view indicates a state in which the through-hole 3e is in contact with the raised portion 4 in a plan view, or a state in which the through-hole 3e is located within a range from the raised portion 4 to substantially a height of the raised portion 4 in a plan view.

[0041] The shape of the through-hole 3e is not particularly limited, but a circular shape, a rectangular shape, or other polygonal shape is also applicable. The number of through-holes 3e arranged for one raised portion 4 may be one, or a plurality of through-holes 3e may be arranged. As in the example in Fig. 4, the through hole 3e is arranged between the end portion 3d and a portion where the raised portion 4 is provided in the terminal electrode 3, that is, a near side of the terminal electrode 3 in a flowing direction of the flow resin 5a with respect to the raised portion 4. <Wirkung in Ausführungsform 1>

[0042] In the present embodiment 1, the raised portion 4 is also arranged on the upper surface of the terminal electrode 3, as in the comparative example. The raised portion 4 can block the flow of the flow resin 5a flowing on the upper surface of the terminal electrode 3, and can promote the flow of the flow resin 5a in the gap at the lower portion of the electrode. As a result, the occurrence of the unfilled portion 9 in the gap at the lower portion of the electrode can be further prevented.

[0043] According to the present embodiment 1, the through-hole 3e, which is located adjacent to the raised portion 4, is arranged in the terminal electrode 3 in a plan view. According to such a configuration, the through-hole 3e blocks the flow of the flow resin 5a flowing on the upper surface of the terminal electrode 3 when the flow resin 5a is injected. The flow resin 5a flowing on the upper surface of the terminal electrode 3 is guided through the through-hole 3e to the gap at the lower portion of the electrode, whereby the flow of the flow resin 5a in the gap at the lower portion of the electrode can be further promoted compared with the case in the comparative example. As a result, the occurrence of the unfilled portion 9 in the gap at the lower portion of the electrode can be further suppressed.

[0044] According to the configuration that the through hole 3e is arranged between the end portion 3d and a portion where as in Fig. 4 illustrates that the raised portion 4 is provided in the terminal electrode 3, the flow resin 5a is guided through the raised portion 4 to the through-hole 3e. Consequently, the flow of the flow resin 5a in the gap at the lower portion of the electrode can be further promoted, and the occurrence of the unfilled portion 9 in the gap at the lower portion of the electrode can be further prevented. <Ausführungsform 2>

[0045] Fig. 5 is a cross-sectional view illustrating a configuration of a semiconductor device according to the present embodiment 2. In the present embodiment 2, the raised portion 4 forms a part of the terminal electrode 3. The raised portion 4 is inclined upward toward the end portion 3d, and an opening of the through hole 3e is aligned with the nozzle 8. In the example in Fig. 5, the cross-sectional view of the raised portion 4 has an arc-like shape, but its shape is not limited to this. The raised portion 4 and the opening of the through-hole 3e, which in Fig. 5 can be formed inexpensively, for example, by a pressing process. According to the present embodiment 2 having such a configuration, the resin-cured material 4c and the adhesive material 4d described in the comparative example are unnecessary, thereby reducing costs.

[0046] A configuration in the present Embodiment 2 is similar to that in Embodiment 1 except for the above point. <Wirkung in Ausführungsform 2>

[0047] In the present Embodiment 2, the raised portion 4 is also arranged on the upper surface of the terminal electrode 3, as in the comparative example and Embodiment 1. The raised portion 4 can block the flow of the flow resin 5a flowing on the upper surface of the terminal electrode 3, and can promote the flow of the flow resin 5a in the gap at the lower portion of the electrode. As a result, the occurrence of the unfilled portion 9 in the gap at the lower portion of the electrode can be further prevented.

[0048] According to the present embodiment 2, the raised portion 4 is inclined upward toward the end portion 3d. Even if the preceding flow resin 5a is pushed by the following flow resin 5a according to such a configuration on the upper surface of the terminal electrode 3, the preceding flow resin 5a can be prevented from spreading beyond the raised portion 4. Consequently, the flow resin 5a can be efficiently guided to the through-hole 3e through the raised portion 4, whereby the flow of the flow resin 5a in the gap at the lower portion of the electrode can be further promoted, and the occurrence of the unfilled portion 9 in the gap at the lower portion of the electrode can be further prevented.

[0049] The raised portion 4 inclined as in the present Embodiment 2 may be applied to the comparative example instead of the Embodiment 1.

[0050] Each embodiment and each comparative example can be combined.< / wirkung> < / herstellungsverfahren>

Claims

[1] Semiconductor device comprising: • a base plate (1a); • a housing (1e) which surrounds a space on the base plate (1a); • a semiconductor element (2) arranged in the space; • a terminal electrode (3) connected to an upper surface of the semiconductor element (2) in the space; • a raised portion (4) arranged on an upper surface of the terminal electrode (3) in the space; • a sealing resin (5) which seals the semiconductor element (2) and the terminal electrode (3) in the space; • a through hole (3e), which is located next to the raised portion (4) in a plan view, is arranged in the terminal electrode (3); wherein • the connection electrode (3) has an end portion (3d) opposite a side wall of the housing (1e), and • the through hole (3e) is arranged between the end portion (3d) and a portion at which the raised portion (4) is provided in the terminal electrode (3). [2] A semiconductor device according to claim 1, wherein the raised portion (4) comprises a resin-cured material (4c). [3] Semiconductor device comprising: • a base plate (1a); • a housing (1e) which surrounds a space on the base plate (1a); • a semiconductor element (2) arranged in the space; • a terminal electrode (3) connected to an upper surface of the semiconductor element (2) in the space; • a raised portion (4) arranged on an upper surface of the terminal electrode (3) in the space; • a sealing resin (5) which seals the semiconductor element (2) and the terminal electrode (3) in the space, wherein • the connection electrode (3) has an end portion (3d) opposite a side wall of the housing (1e), and • the raised section (4) is inclined upwards towards the end section (3d). [4] A semiconductor device according to any one of claims 1 to 3, wherein • the terminal electrode (3) has a first terminal electrode (3a) and a second terminal electrode (3b) which are separated from each other, and • the raised section (4) has: ◯ a first raised portion (4a) arranged on an upper surface of the first terminal electrode (3a) on the side of the second terminal electrode (3b); and ◯ a second raised portion (4b) disposed on an upper surface of the second terminal electrode (3b) on the side of the first terminal electrode (3a). [5] A method of manufacturing the semiconductor device according to any one of claims 1 to 4, wherein • the connection electrode (3) has an end portion (3d) opposite a side wall of the housing (1e), and • a flow resin (5a), which is the sealing resin (5), is injected into the space from above the side of the end portion of the raised portion (4).

Images