Semiconductor device, power conversion device, moving body and method for manufacturing a semiconductor device

Abstract

Semiconductor device comprising: an insulating substrate (1) on which a metal structure (2) having a first recess (2a) and a second recess (2b) arranged side by side and a semiconductor element (4) are arranged; an electronic component (5) partially arranged in the first recess (2a); and a solder (6) connecting the metal structure (2) and the electronic component (5).

Description

Field of InterestThe present disclosure relates to a semiconductor device, a power converter, a moving body, and a method of manufacturing a semiconductor device.Background ArtIn a manufacturing process of a semiconductor device, an electronic component is electrically connected to a metal pattern disposed on an insulating substrate after the electronic component is aligned with the metal pattern in some cases. However, before the metal pattern and the electronic component are joined, the electronic component may move in an in-plane direction of an insulating substrate due to, for example, transport of the insulating substrate, and displacement of the electronic component may occur. In this case, there is a problem that the electronic component needs to be re-aligned.In order to solve such a problem, Patent Document 1 proposes a technique for regulating movement of an electronic component through a side wall of a thick metal structure.Prior Art DocumentPatent DocumentPatent Document 1: JP H11-345 969 A (1999)Patent Document 2: JP 2016-58 594 APatent Document 3: U.S. Pat. No. 6,316,736 B1SummaryProblem to be Solved by the InventionIn recent years, as a bonding member for electrically connecting a metal pattern and an electronic component, it has been proposed to use a solder ball whose usage amount is easy to handle. However, since a ball-shaped solder ball is easy to roll, the use of a solder ball in a configuration of a conventional technique may result in displacement of the solder ball before the solder ball melts. Therefore, there is a problem that a jig for suppressing displacement of the solder ball is required.The present disclosure has been made in view of the above problems, and an object of the present disclosure is to provide a technique capable of suppressing displacement of an electronic component and a solder ball without using a jig.Means for Solving the ProblemA semiconductor device according to the present disclosure includes: an insulating substrate on which a metal pattern having a first recess and a second recess arranged side by side and a semiconductor element are arranged; an electronic component partially arranged in the first recess; and a solder connecting the metal pattern and the electronic component.Effects of the InventionAccording to the present disclosure, since the metal structure includes the first recess and the second recess, displacement of the electronic component and the solder ball can be suppressed without using a jig.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 DrawingsFIG. 1 is a plan view for explaining a manufacturing process of a related semiconductor device. FIG. 2 is a perspective cross-sectional view for explaining the manufacturing process of the related semiconductor device. FIG. 3 is a perspective cross-sectional view for explaining the manufacturing process of the related semiconductor device. FIG. 4 is a perspective cross-sectional view for explaining the manufacturing process of the related semiconductor device. FIG. 5 is a perspective cross-sectional view for explaining a manufacturing process of a semiconductor device according to a first embodiment. FIG. 6 is a perspective cross-sectional view for explaining the manufacturing process of the semiconductor device according to the first embodiment. FIG. 7 is a perspective cross-sectional view for explaining the manufacturing process of the semiconductor device according to the first embodiment. FIG. 8 is a cross-sectional view illustrating a configuration of the semiconductor device according to the first embodiment. FIG. 9 is a block diagram illustrating a power conversion device according to a second embodiment. FIG. 10 is a block diagram illustrating a moving body according to a third embodiment.DESCRIPTION OF THE EMBODIMENTSHereinafter, embodiments will be described with reference to the accompanying drawings. Features described in the following embodiments are examples, and not all features are essential. In the following description, similar constituent elements are denoted by identical or similar reference numerals in a plurality of embodiments, and different constituent elements are mainly described. In addition, in the following description, specific positions and directions such as "upper", "lower", "left", "right", "front", and "rear" do not necessarily have to coincide with directions in an actual implementation.< Semiconductor Device>Before describing a semiconductor device according to a first embodiment, a manufacturing process of a semiconductor device related to the semiconductor device according to the first embodiment (hereinafter referred to as a "related semiconductor device") will be described first. Note that the related semiconductor device is, for example, a power semiconductor device.FIG. 1 is a plan view for explaining a positioning step in a manufacturing process of the related semiconductor device. FIG. 2 is a perspective cross-sectional view of a portion indicated by a dotted frame A in FIG. 1 before the positioning step.Before the positioning step of the related semiconductor device is performed, an insulating substrate 1 is prepared on which a metal pattern 2 is disposed as illustrated in FIG. 2. The metal structure 2 has two partial regions separated from each other, and two solder resists 3 are respectively arranged on the two partial regions. The solder resists 3 have a U-shape as a planar shape, the openings of which face each other.An upper portion of the metal pattern 2 is substantially flat here, and a solder ball used as a bonding member of the metal pattern 2 has a spherical shape. For this reason, even in a case where the solder ball is placed at a designated position on the metal pattern 2 where the solder ball is to be melted, the solder ball can be displaced from the designated position when the insulating substrate 1 is transported to a reflow device for melting the solder ball.In view of this, in the positioning step of the related semiconductor device, the insulating substrate 1 and a first jig 51 for positioning the insulating substrate 1 are sequentially placed on a base plate 8 such as a heat sink in FIG. 1, and then a second jig 52 is fitted into a hole of the first jig 51. Thereafter, a semiconductor chip 4 which is a semiconductor element, an electronic component 5, and a ball-shaped solder ball are inserted into a hole of the second jig 52.FIG. 3 is a perspective cross-sectional view of a portion indicated by a dotted frame A in FIG. 1 after the insertion is performed, and FIG. 4 is a cross-sectional view of FIG. 3. The metal pattern 7 is disposed on a surface of the insulating substrate 1 opposite to a surface on which the metal pattern 2 is disposed. The bonding member 9 is, for example, a solder and is disposed between the metal pattern 7 and the base plate 8.As illustrated in FIG. 3, both ends of the electronic component 5 are placed on the metal pattern 2 so as to be inside the U-shapes of the two solder resists 3. As illustrated in FIGS. 3 and 4, two solder balls 6 aare placed on portions of the metal pattern 2 that are near the both ends of the electronic component 5.As illustrated in FIGS. 3 and 4, the second jig 52 is provided around the electronic component 5 and the solder balls 6 a. Accordingly, the second jig 52 restricts movement of the cylindrical electronic component 5 and the spherical solder balls 6 ain an in-plane direction of the insulating substrate 1.In the manufacturing process of the related semiconductor device, after the positioning step, a transportation of the insulating substrate 1 to a reflow device and a reflow step for melting the solder balls 6 aare performed. In this way, a solder is formed from the solder balls 6 a, which electrically connects both ends of the electronic component 5 and the two partial regions of the metal structure 2. As a result, the two partial regions of the metal structure 2 are electrically connected to the electronic component 5 arranged therebetween.Although not illustrated, in this reflow step, the semiconductor chip 4 is also electrically connected to the metal pattern 2 and others by a bonding member such as solder. Thereafter, the first jig 51 and the second jig 52 are removed from the insulating substrate 1.According to the manufacturing process of the related semiconductor device described above, displacement of the electronic component 5 and the solder balls 6 acan be suppressed to some extent. However, in the manufacturing process of the related semiconductor device, there is a problem that the second chuck 52 is required for the dedicated purpose. In addition, there is a problem that the electronic component 5 and the solder balls 6 aare displaced by an amount corresponding to a clearance between the second jig 52, the first jig 51, and the insulating substrate 1. On the other hand, in the embodiments of the present disclosure described below, such problems can be solved.< Embodiment>FIGS. 5 and 6 are perspective cross-sectional views for explaining a manufacturing process of a semiconductor device according to the first embodiment, and FIG. 7 is a cross-sectional view of FIGS. 6. FIGS. 5 to 7 correspond to FIGS. 2 to 4, respectively. Among constituent elements according to the first embodiment, hereinafter, constituent elements identical or similar to the constituent elements described above are denoted by identical or similar reference numerals, and different constituent elements will be mainly described.Before a positioning step of the semiconductor device according to the first embodiment, an insulating substrate 1 is prepared on which a metal pattern 2 having a first recess 2 aand a second recess 2 bis disposed as illustrated in FIG. 5. The first depression 2 ais formed, for example, by etching the metal structure 2 at a provided position of the electronic component 5. The second recess 2 bis formed by etching the metal pattern 2 at a predetermined position of a solder ball 6 a, for example, and is disposed adjacent to the first recess 2 a.As illustrated in FIG. 7, in the first embodiment, inner walls of the first recess 2 aand the second recess 2 bare inclined, and the first recess 2 aand the second recess 2 bhave cross-sectional shapes that expand toward an opening of the first recess 2 aand an opening of the second recess 2 b, respectively. As illustrated in FIG. 5, in the first embodiment, the first recess 2 aand the second recess 2 bare separated from each other.An opening shape of the first recess 2 ain plan view is a U shape in the example of FIG. 5, but is not limited thereto. An opening shape of the second recess 2 bin plan view is a quadrangular shape in the example of FIG. 5, but is not limited to this, and may be, for example, a circular shape.A solder resist 3 is disposed on the metal pattern 2 and has a planar shape surrounding the first recess 2 aand the second recess 2 b. In the example of FIG. 5, the solder resist 3 has a U-shaped planar shape surrounding the first recess 2 aand the second recess 2 b; however, the planar shape of the solder resist 3 is not limited thereto.As illustrated in FIGS. 6 and 7, a part of the electronic component 5 is inserted into the first recess 2 aand a part of the solder ball 6 ais inserted into the second recess 2 b. As a result, displacement of the cylindrical electronic component 5 by the inner wall of the first recess 2 ais suppressed, and displacement of the spherical solder ball 6 aby the inner wall of the second recess 2 bis suppressed.Thereafter, the insulating substrate 1 is transported to a reflow device, and a reflow step for melting the solder ball 6 ais performed. By this fusion process, a solder for connecting the metal pattern 2 and the electronic component 5 is formed.Note that a semiconductor chip 4 is disposed on the insulating substrate 1 before, after, or between the positioning step and the melting step described above. For example, the semiconductor chip 4 is electrically connected to the metal structure 2 and ultimately to the electronic component 5 by a bonding component such as solder.FIG. 8 is a cross-sectional view illustrating the semiconductor device after the reflow step according to the first embodiment and corresponds to FIG. 7. As described above, the semiconductor device of FIG. 8 includes the insulating substrate 1 on which the metal pattern 2 including the first recess 2 aand the second recess 2 bis disposed, and the electronic component 5 partially disposed in the first recess 2 a. The semiconductor device of FIG. 8 includes a solder 6 formed by melting the solder ball 6 a.The solder 6 electrically connects both ends of the electronic component 5 and the two partial regions of the metal structure 2. In the first embodiment, a part of the solder 6 is disposed in the second recess 2 b. According to such a configuration, a contact area between the solder 6 and the metal pattern 2 can be increased, and therefore it is possible to suppress detachment of the solder 6 from the metal pattern 2 and to increase the reliability of the semiconductor device.Moreover, as described above, in the first embodiment, the first recess 2 aand the second recess 2 bhave cross-sectional shapes that respectively expand toward the opening of the first recess 2 aand the opening of the second recess 2 b. According to such a configuration, it is possible to suppress positional deviation and inclination of the electronic component 5 and the solder ball 6 abefore the reflow step, and therefore it is possible to enhance the bonding capability of the solder 6. In addition, since the inner wall of the second recess 2 bis inclined, the solder which is just melted can easily flow toward the electronic component 5 along the inner wall. As a result, the bonding ability of the solder 6 can be improved, and therefore the reliability of the semiconductor device can be increased.In the first embodiment as described above, the solder resist 3 has a planar shape surrounding the first recess 2 aand the second recess 2 b. According to such a configuration, a wetting area of the solder that is just melted can be limited, and therefore the solder can easily flow to the electronic component 5. As a result, the shape and thickness of a fillet (fill) can be secured, and therefore it is possible to improve the bonding capability of the solder 6 and to increase the reliability of the semiconductor device.If the first recess 2 aand the second recess 2 bare not separated from each other, it is considered that the solder that is just melted flows from the second recess 2 balong the first recess 2 ato a space below the electronic component 5 in some cases. In this case, it is assumed that the two divided portions of the metal pattern 2 are connected by the solder, and a short circuit occurs in some cases. On the other hand, in the first embodiment, since the first recess 2 aand the second recess 2 bare separated from each other as described above, such short-circuit can be suppressed.< Embodiment>A power converter according to the second embodiment includes a main conversion circuit including the semiconductor device according to the first embodiment. A case where the semiconductor device according to the first embodiment is used for a three-phase inverter will be described below as the second embodiment, although the semiconductor device described above is not limited to a specific power conversion device.FIG. 9 is a block diagram illustrating a configuration of a power conversion system to which the power conversion device according to the second embodiment is applied.The power conversion system illustrated in FIG. 9 includes a power supply 100, a power converter 200, and a load 300. The power supply 100 is a DC power supply, and provides DC power to the power conversion device 200. The power supply 100 may be any of various power supplies, and may be, for example, a DC system, a solar cell, or a rechargeable battery, or may be a rectifier circuit or an AC / DC converter connected to an AC system. Alternatively, the power supply 100 may be a DC / DC converter that converts DC power output from a DC system into a predetermined power.The power converter 200 is a three-phase inverter connected between the power supply 100 and the load 300, converts DC power supplied from the power supply 100 into AC power, and supplies the AC power to the load 300. As illustrated in FIG. 9, the power conversion device 200 includes a main conversion circuit 201 that converts DC power into AC power and outputs the AC power, a drive circuit 202 that outputs a drive signal for driving each switching element of the main conversion circuit 201, and a control circuit 203 that outputs a control signal for controlling the drive circuit 202 to the drive circuit 202.The load 300 is a three-phase electric motor that is driven by the AC power supplied from the power conversion device 200. The load 300 is not limited to a specific application, and is an electric motor mounted on various electric devices, and is used as, for example, an electric motor for a hybrid vehicle, an electric vehicle, a rail vehicle, a lift, or an air conditioner.Details of the power conversion device 200 will be described below. The main conversion circuit 201 includes a switching element and a free wheeling diode (not illustrated), converts DC power provided from the power supply 100 to AC power by switching the switching element, and provides the AC power to the load 300. Although various configurations are available as specific circuit configurations of the main conversion circuit 201, the main conversion circuit 201 according to the second embodiment is a three-phase full bridge circuit having two levels, and may include six switching elements and six free wheeling diodes connected in antiparallel with the respective switching elements. Each switching element of the main conversion circuit 201 is the semiconductor device according to the first embodiment. Two each of the six switching elements are connected in series to form upper and lower arms, and the upper and lower arms form phases (a U phase, a V phase, a W phase) of the full bridge circuit. Output terminals of the upper and lower arms, that is, three output terminals of the main conversion circuit 201, are connected to the load 300.The driving circuit 202 generates a driving signal for driving the switching elements of the main conversion circuit 201, and provides the driving signal to control electrodes of the switching elements of the main conversion circuit 201. Specifically, according to a control signal from the control circuit 203 described later, the drive circuit 202 outputs a drive signal for turning on the switching elements and a drive signal for turning off the switching elements to the control electrodes of the switching elements. If the switching elements are maintained in an ON state, the drive signal is a voltage signal (ON signal) that is equal to or higher than a threshold voltage of the switching elements, and if the switching elements are maintained in an OFF state, the drive signal is a voltage signal (OFF signal) that is equal to or lower than the threshold voltage of the switching elements.The control circuit 203 controls the switching elements of the main conversion circuit 201 so as to provide desired power to the load 300. Specifically, the control circuit 203 calculates a time (ON time) during which each switching element of the main conversion circuit 201 is to be in an ON state, based on the power to be supplied to the load 300. For example, the control circuit 203 may control the main conversion circuit 201 by pulse width modulation (PWM) control for modulating the ON time of the switching elements according to a voltage to be output. The control circuit 203 then outputs a control command (a control signal) to the drive circuit 202 so that an ON signal is output to a switching element to be in an ON state at each time point and an OFF signal is output to a switching element to be in an OFF state at each time point. The drive circuit 202 outputs an ON signal or an OFF signal as a drive signal to the control electrode of each switching element according to the control signal.In the power conversion device according to the second embodiment described above, the semiconductor device according to the first embodiment is used as the switching elements of the main conversion circuit 201, and therefore it is possible to realize a power conversion device with enhanced reliability.Although an example in which the semiconductor device according to the first embodiment is used for a two-level three-phase inverter has been described in the second embodiment described above, the second embodiment is not limited to this, and the semiconductor device according to the first embodiment can be used for various power conversion devices. Although the semiconductor device according to the first embodiment is a two-level power conversion device in the second embodiment, the semiconductor device according to the first embodiment may be a three-level or more-level power conversion device or the semiconductor device may be used for a single-phase inverter if power is supplied to a single-phase load. If power is supplied to a DC load or the like, the semiconductor device may be used for a DC / DC converter or an AC / DC converter.Moreover, the power conversion device according to the second embodiment is not limited to the case where the load is an electric motor, and can be used as, for example, a power supply device of an electric discharge machine, a laser beam machine, an induction heating cooker, or a contactless power supply system, and can also be used as a power conditioner of a solar power generation system, an energy storage system, or the like.< Embodiment>FIG. 10 is a diagram illustrating a configuration of a moving body according to a third embodiment. The power conversion device 200 according to the second embodiment is mounted on a moving body 400 illustrated in FIG. 10, and the moving body 400 can be moved with an output from the power conversion device 200. According to such a configuration, the operational safety of the moving body 400 can be increased. Although a case where the moving body 400 is a rail vehicle has been described, the moving body 400 is not limited thereto, and may be, for example, a hybrid vehicle, an electric vehicle, a lift, or the like.The embodiments may be combined.Explanation of Reference Numerals1 Insulating substrate 2 Metal pattern 2 aFirst recess 2 bSecond recess 3 Solder resist 4 Semiconductor chip 5 Electronic component 6 Solder 6 a Metal ball

Claims

A semiconductor device comprising: an insulating substrate (1) on which a metal pattern (2) having a first recess (2a) and a second recess (2b) arranged side by side and a semiconductor element (4) are arranged; an electronic component (5) partially arranged in the first recess (2a); and a solder (6) connecting the metal pattern (2) and the electronic component (5).The semiconductor device according to claim 1, wherein the first recess (2a) and the second recess (2b) have cross-sectional shapes that expand toward an opening of the first recess (2a) and an opening of the second recess (2b), respectively.The semiconductor device according to claim 1 or 2, further comprising a solder resist (3) disposed on the metal pattern (2) and having a planar shape surrounding the first recess (2a) and the second recess (2b).The semiconductor device according to any one of claims 1 to 3, wherein a part of the solder (6) is disposed in the second recess (2b).The semiconductor device according to any one of claims 1 to 4, wherein the first recess (2a) and the second recess (2b) are separated from each other.A power conversion device comprising: a main conversion circuit including the semiconductor device according to any one of claims 1 to 5 and converting input power and outputting the converted power; a drive circuit outputting a drive signal for driving the semiconductor device to the semiconductor device; and a control circuit outputting a control signal for controlling the drive circuit to the drive circuit.A moving body comprising the power conversion device according to claim 6.A method of manufacturing a semiconductor device, the method comprising: preparing an insulating substrate (1) on which a metal pattern (2) having a first recess (2a) and a second recess (2b) arranged side by side is arranged; inserting a part of an electronic component (5) into the first recess (2a); inserting a part of a solder ball (6a) into the second recess (2b); forming a solder (6) connecting the metal pattern (2) and the electronic component (5) by melting the solder ball (6a); and arranging a semiconductor element (4) on the insulating substrate (1).

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