Semiconductor device manufacturing method, semiconductor device, power conversion device and mobile body

Abstract

A semiconductor chip (6, 7) is connected to a metal pattern (5). A collapsed surface (15) of an electrode (9) is bonded to the metal pattern (5). A burr (20) exists at the end of a burr surface (16) of the electrode (9). The amount of collapse at the end of the burr surface (16) is less than or equal to 10 μm.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a semiconductor device in which an electrode and a metal pattern are bonded, a semiconductor device, a power conversion device, and a mobile body. Background Art

[0002] If the electrode is formed by punching (for example, see Patent Document 1 (Paragraphs 0012, Figure 2 When the collapsed angle surface of the electrode is ultrasonically bonded to the metal pattern, light is irradiated to the burred surface of the electrode, and image recognition and alignment are performed by a camera of the ultrasonic bonding device.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 09-312373 Summary of the invention

[0004] During punching, the burr surface is sometimes accidentally punched in the continuous die, which will crush the burr. In this case, the periphery of the electrode becomes blurred in the camera image, and sometimes the shape of the electrode cannot be clearly imaged, which may cause misrecognition. Therefore, the joining quality of ultrasonic joining is reduced, so there is a problem of damaging reliability. In addition, sometimes due to recognition errors, the device stops operating and other failures occur. Therefore, the ultrasonic joining operation of the electrode is time-consuming and requires the operator to be present at all times. It is impossible to reduce working hours and it is difficult to convert to automation. As a result, there is a problem of reduced production efficiency.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a semiconductor device, a semiconductor device, a power conversion device, and a mobile body capable of improving reliability and production efficiency.

[0006] The semiconductor device involved in the present invention is characterized in that it has: a metal pattern; a semiconductor chip connected to the metal pattern; and an electrode having a collapsed surface joined to the metal pattern and a burred surface with burrs at the end, and the amount of collapse of the end of the burred surface is less than or equal to 10μm.

[0007] Effects of the Invention

[0008] In the present invention, the amount of collapse of the end of the burr surface is set to be less than or equal to 10 μm. This prevents misidentification of the electrode and improves the quality of ultrasonic bonding. As a result, reliability and production efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is a cross-sectional view showing the semiconductor device according to the first embodiment.

[0010] Figure 2 It is an oblique view showing the electrodes.

[0011] Figure 3 is a side view showing the electrodes.

[0012] Figure 4 Yes Figure 3 An enlarged oblique view of the circled part.

[0013] Figure 5 is a cross-sectional view of the electrode.

[0014] Figure 6 This is an enlarged perspective view of the cut portion of the electrode.

[0015] Figure 7 This is a cross-sectional view showing how the collapsed surface of the electrode is ultrasonically bonded to the metal pattern.

[0016] Figure 8 This is a cross-sectional view showing how the burred surface of the electrode is ultrasonically bonded to the metal pattern.

[0017] Fig. 9 It is a cross-sectional view showing the manufacturing process of the semiconductor device involved in the first embodiment.

[0018] Fig.10 It is a cross-sectional view showing the manufacturing process of the semiconductor device involved in the first embodiment.

[0019] Fig.11 This is a cross-sectional view showing an electrode in which the amount of collapse at the end of the burr surface is 10 μm or less.

[0020] Fig.12 This is a cross-sectional view showing an electrode in which the amount of collapse at the end of the burr surface is larger than 10 μm.

[0021] Fig.13 This is a diagram showing experimental data obtained by investigating the amount of crushing at the end of the burr surface and whether or not it can be recognized by a camera.

[0022] Fig.14 It is a perspective view showing electrodes of a semiconductor device according to the second embodiment.

[0023] Fig.15 It is a perspective view showing electrodes of a semiconductor device according to a third embodiment.

[0024] Fig.16 : is a block diagram showing the configuration of a power conversion system to which the power conversion device according to the fourth embodiment is applied.

[0025] Fig.17 This is a diagram showing a moving object involved in Embodiment 5. DETAILED DESCRIPTION

[0026] A method for manufacturing a semiconductor device, a semiconductor device, a power conversion device, and a mobile object according to the embodiments will be described with reference to the accompanying drawings. The same or corresponding components are denoted by the same reference numerals, and duplicate descriptions may be omitted.

[0027] Implementation method 1.

[0028] Figure 1 1 is a cross-sectional view showing a semiconductor device according to Embodiment 1. A metal pattern 3 on the lower surface of an insulating substrate 2 is bonded to a heat sink 1 by solder 4. The lower surface electrodes of semiconductor chips 6 and 7 are connected to a metal pattern 5 on the upper surface of the insulating substrate 2. The upper surface electrodes of the semiconductor chips 6 and 7 are connected to each other by a wire 8. An electrode 9 is ultrasonically bonded to the metal pattern 5. A housing 10 is bonded to the heat sink 1 by an adhesive 11 so as to surround the insulating substrate 2 and the semiconductor chips 6 and 7. In the housing 10, the insulating substrate 2 and the semiconductor chips 6 and 7 are encapsulated by an encapsulation material 12. A cover 13 is bonded to the housing 10 by an adhesive 14. A portion of the electrode 9 is led out from the cover 13.

[0029] Figure 2 It is an oblique view showing the electrodes. Figure 3 is a side view showing the electrodes. Figure 4 Yes Figure 3 An enlarged oblique view of the circled part. Figure 5 is a cross-sectional view of the electrode. Figure 6 This is an enlarged perspective view of the cut portion of the electrode. The electrode 9 is formed by punching using a continuous die. The opposite side of the collapsed angle surface 15 of the electrode 9 becomes a burr surface 16. There are shearing portions 17 and fracture portions 18 on the cut surface of the punched electrode 9. There is a collapsed angle 19 at the end of the collapsed angle surface 15. There is a burr 20 at the end of the burr surface 16 of the electrode 9. The burr 20 is also called a burr.

[0030] In ultrasonic bonding, metals are brought into contact with each other, and the oxide film and stains on the metal surface are destroyed by ultrasonic vibration and amplitude, and the cleaned surfaces of the metal surfaces are pressed together to bond. The larger the bonding area, the higher the bonding quality of ultrasonic bonding. Figure 7 This is a cross-sectional view showing a state where the collapsed surface of the electrode is ultrasonically bonded to the metal pattern. The center portion of the collapsed surface 15 of the electrode 9 is in contact with the metal pattern 5, and the bonding area becomes larger. Figure 8 This is a cross-sectional view showing the situation of ultrasonically bonding the burr surface of the electrode to the metal pattern 5. Since only the burr 20 portion is bonded to the metal pattern 5, the bonding area is small. Therefore, in this embodiment, the collapsed angle surface 15 of the electrode 9 is ultrasonically bonded to the metal pattern 5.

[0031] Next, a method for manufacturing the semiconductor device according to this embodiment will be described. Fig. 9 and Fig.10 1 is a cross-sectional view showing the manufacturing process of the semiconductor device according to the first embodiment. The semiconductor chips 6 and 7 are connected to the metal pattern 5 of the insulating substrate 2. The electrode 9 is formed by punching. Next, as shown in FIG. Fig. 9 As shown, light is irradiated on the burr surface 16 of the electrode 9, and the burr surface 16 is image-recognized and aligned by the camera 21 of the ultrasonic bonding device. Fig.10 As shown, the ultrasonic bonding tool 22 is pressed against the burred surface 16 of the electrode 9 , and the collapsed surface 15 of the electrode 9 is ultrasonically bonded to the metal pattern 5 .

[0032] Here, if the electrode 9 is punched, a burr 20 is formed on the entire end of the electrode 9 after it is cut. Each time the workbench moves forward, the burr 20 is crushed several times by the stripper plate and the drawing plate. As a result, most of the burr 20 is crushed, and the end of the burr surface 16 is recessed by several μm. If the amount of crushing at the end of the burr surface 16 is large, the periphery of the electrode 9 becomes blurred in the camera image, and the shape of the electrode 9 cannot be clearly imaged, resulting in misrecognition and failure of the joining process. Here, the crushing amount refers to the height difference from the flat surface in the center of the burr surface 16 to the bottom of the crushed part of the end of the burr surface 16.

[0033] Fig.11 This is a cross-sectional view showing an electrode in which the amount of collapse at the end of the burr surface is 10 μm or less. Fig.12 This is a cross-sectional view showing an electrode in which the amount of collapse at the end of the burr surface is larger than 10 μm.

[0034] Fig.13 This is a graph showing experimental data obtained by investigating the amount of crushing at the end of the burr surface and whether it can be recognized by a camera. When the amount of crushing at the end of the burr surface 16 is 13 to 20 μm, misidentification occurs, and when it is 7 to 10 μm, the electrode 9 can be correctly recognized. Therefore, in this embodiment, the amount of crushing at the end of the burr surface 16 is less than or equal to 10 μm by optimizing the stroke amount and speed of the punching in the punching process of the electrode 9. As a result, misidentification of the electrode 9 is prevented, and the joining quality of the ultrasonic joining is improved. As a result, reliability and production efficiency can be improved.

[0035] Implementation method 2.

[0036] Fig.142 is a perspective view showing an electrode of a semiconductor device according to Embodiment 2. In this embodiment, a camera-recognizable mark shape 23 is provided at the corners, for example, four corners or two diagonal corners, of the burr surface 16 of the electrode 9 pressed by the ultrasonic bonding tool 22. The mark shape 23 is a circular depression formed by half etching or the like. By forming such a physical depression, the recognizability of the electrode 9 and the camera recognition accuracy are further improved, thereby further improving the bonding quality and production efficiency.

[0037] When an actual image of the burred surface 16 of the electrode 9 after ultrasonic welding is confirmed, the burrs 20 and the marking shape 23 remain recognizable after welding, although they are partially deformed due to contact with the ultrasonic welding tool 22 .

[0038] In addition, the marking shape 23 can also be formed by mechanical processing such as a punch press, and can also be in a conical shape or a pyramidal shape. By forming the marking shape 23 by mechanical processing, the marking shape 23 becomes clear, and the recognition of the electrode 9 and the camera recognition accuracy are further improved. In addition, quantitative management can also be achieved.

[0039] Implementation method 3.

[0040] Fig.15 1 is a perspective view showing an electrode of a semiconductor device according to Embodiment 3. In this embodiment, the marking shape 23 is L-shaped. The marking shape 23 is a groove with a depth of about 0.5 mm, formed by machining. Due to the L-shaped marking shape 23, the recognizability of the electrode 9 and the camera recognition accuracy are further improved.

[0041] In embodiments 1-3, semiconductor chips 6 and 7 are IGBTs, MOSFETs, diodes (Diode) or SBDs formed of silicon. However, semiconductor chips 6 and 7 are not limited to being formed of silicon, and can also be formed of wide bandgap semiconductors with a larger bandgap than silicon. Wide bandgap semiconductors are, for example, silicon carbide, gallium nitride materials or diamonds. Power semiconductor elements formed by such wide bandgap semiconductors can be miniaturized because of their high voltage resistance and allowable current density. By using the miniaturized element, the semiconductor module assembled with the element can also be miniaturized. In addition, since the heat resistance of the element is high, the heat dissipation fins of the radiator can be miniaturized, and the water cooling part can be air-cooled, so that the semiconductor module can be further miniaturized. In addition, since the power loss of the element is low and efficient, the semiconductor module can be made efficient. In addition, if it is a semiconductor device involved in this embodiment, even if it is used in a high temperature environment, the ultrasonic bonding life of the electrode 9 can be stably ensured.

[0042] Implementation method 4.

[0043] This embodiment is to apply the semiconductor device involved in the above-mentioned embodiments 1 to 3 to a power conversion device. The power conversion device is, for example, an inverter device, a converter device, a servo amplifier, a power supply unit, etc. The present invention is not limited to a specific power conversion device, but the following describes the case where the present invention is applied to a three-phase inverter.

[0044] Fig.16 1 is a block diagram showing the structure of a power conversion system, in which the power conversion device according to Embodiment 4 is applied. The power conversion system includes a power supply 100, a power conversion device 200, and a load 300. The power supply 100 is a DC power supply, and supplies DC power to the power conversion device 200. The power supply 100 can be composed of various power supplies, for example, it can be composed of a DC system, a solar cell, a storage battery, or a rectifier circuit or an AC / DC converter connected to an AC system. In addition, the power supply 100 can also be composed of a DC / DC converter that converts the DC power output from the DC system into a predetermined power.

[0045] The power conversion device 200 is a three-phase inverter connected between the power source 100 and the load 300, and converts the DC power supplied from the power source 100 into AC power, and supplies the AC power to the load 300. The power conversion device 200 includes: a main conversion circuit 201 that converts the DC power into AC power and outputs it; 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.

[0046] Load 300 is a three-phase motor driven by AC power supplied from power converter 200. Load 300 is not limited to a specific use, and is a motor mounted on various electrical devices, for example, a motor for hybrid vehicles, electric vehicles, railway vehicles, elevators, or air conditioners.

[0047] The power conversion device 200 is described in detail below. The main conversion circuit 201 has a switching element and a freewheeling diode (not shown), and converts the DC power supplied from the power supply 100 into AC power by turning the switching element on and off, and supplies it to the load 300. There are various structures for the specific circuit structure of the main conversion circuit 201, but the main conversion circuit 201 involved in this embodiment is a two-level three-phase full-bridge circuit, which can be composed of 6 switching elements and 6 freewheeling diodes connected in reverse parallel to each switching element. Each switching element of the main conversion circuit 201 is composed of a semiconductor device equivalent to any of the above-mentioned embodiments 1 to 3. The 6 switching elements are connected in series two by two to form upper and lower bridge arms, and each upper and lower bridge arm constitutes each phase (U phase, V phase, W phase) of the full-bridge circuit. In addition, the output terminals of each upper and lower bridge arm, that is, the three output terminals of the main conversion circuit 201, are connected to the load 300.

[0048] The drive circuit 202 generates a drive signal for driving the switch element of the main conversion circuit 201, and supplies it to the control electrode of the switch element of the main conversion circuit 201. Specifically, according to the control signal from the control circuit 203 described later, a drive signal for setting the switch element to the on state and a drive signal for setting the switch element to the off state are output to the control electrode of each switch element. When the switch element is maintained in the on state, the drive signal is a voltage signal greater than or equal to the threshold voltage of the switch element (on signal), and when the switch element is maintained in the off state, the drive signal becomes a voltage signal less than or equal to the threshold voltage of the switch element (off signal).

[0049] The control circuit 203 controls the switch elements of the main conversion circuit 201 to supply the desired power to the load 300. Specifically, based on the power to be supplied to the load 300, the time (on time) at which each switch element of the main conversion circuit 201 should be in the on state is calculated. For example, the main conversion circuit 201 can be controlled by PWM control that modulates the on time of the switch element corresponding to the voltage to be output. In addition, a control instruction (control signal) is output to the drive circuit 202 to output an on signal to the switch element that should be in the on state and an off signal to the switch element that should be in the off state at each moment. The drive circuit outputs the on signal or the off signal as a drive signal to the control electrode of each switch element according to the control signal.

[0050] In the power conversion device according to the present embodiment, each switching element of the main conversion circuit 201 is formed of a semiconductor device corresponding to any of the above-mentioned Embodiments 1 to 3. This can improve reliability and production efficiency.

[0051] In this embodiment, an example of applying the present invention to a two-level three-phase inverter is described, but the present invention is not limited thereto and can be applied to various power conversion devices. In this embodiment, a two-level power conversion device is used, but a three-level or multi-level power conversion device may also be used. In the case of supplying power to a single-phase load, the present invention may also be applied to a single-phase inverter. In addition, in the case of supplying power to a DC load, etc., the present invention may also be applied to a DC / DC converter or an AC / DC converter.

[0052] In addition, the power conversion device to which the present invention is applied is not limited to the case where the above-mentioned load is an electric motor. For example, it can also be used as a power supply device for an electric discharge machine, a laser processing machine, an induction heating cooker, or a contactless power supply system, and can also be used as a power conditioner for a solar power generation system or a power storage system.

[0053] Implementation method 5.

[0054] Fig.17 This is a diagram showing a moving object according to Embodiment 5. This moving object 400 is a train or the like, and electric power is controlled using the power conversion device 200 according to Embodiment 4. This can improve reliability and production efficiency.

[0055] Description of the label

[0056] 5 metal pattern, 6, 7 semiconductor chip, 9 electrode, 15 collapsed surface, 16 burr surface, 20 burr, 21 camera, 22 ultrasonic bonding tool, 23 marking shape, 200 power conversion device, 201 main conversion circuit, 202 drive circuit, 203 control circuit, 400 moving body

Claims

1. A method for manufacturing a semiconductor device, characterized in that: It has the following processes: connecting semiconductor chips to metal patterns; forming electrodes by punching; and The burr surface of the electrode is identified by a camera, and an ultrasonic bonding tool is pressed to ultrasonically bond the collapsed angle surface of the electrode to the metal pattern. There are burrs at the ends of the burr surface. The amount of collapse of the end portion of the burred surface is less than or equal to 10 μm.

2. A method for manufacturing a semiconductor device, characterized in that: It has the following processes: connecting semiconductor chips to metal patterns; Forming electrodes by blanking; forming a marking shape at a corner of the burr surface of the electrode; and The burred surface formed with the mark shape is recognized by a camera, and an ultrasonic bonding tool is pressed to ultrasonically bond the collapsed angle surface of the electrode to the metal pattern. There are burrs at the end of the burr surface, and the amount of collapse of the end of the burr surface is less than or equal to 10 μm.

3. The method for manufacturing a semiconductor device according to claim 2, wherein: The mark shape is formed by machining.

4. A semiconductor device, characterized in that: have: Metallic patterns; a semiconductor chip connected to the metal pattern; and an electrode having a collapsed surface joined to the metal pattern and a burr surface having burrs at an end thereof, The amount of collapse of the end portion of the burred surface is less than or equal to 10 μm.

5. A semiconductor device, characterized in that: have: Metallic patterns; a semiconductor chip connected to the metal pattern; and an electrode having a collapsed surface joined to the metal pattern and a burr surface having burrs at an end thereof, A marking shape is provided at the corner of the burr surface. There are burrs at the end of the burr surface, and the amount of collapse of the end of the burr surface is less than or equal to 10 μm.

6. The semiconductor device according to claim 5, wherein: The mark is in an L-shape.

7. The semiconductor device according to any one of claims 4 to 6, characterized in that The semiconductor chip is formed of a wide bandgap semiconductor.

8. A power conversion device, comprising: A main conversion circuit comprising a semiconductor device according to any one of claims 4 to 7, the main conversion circuit converting input power and outputting the converted power; a driving circuit that outputs a driving signal for driving the semiconductor device to the semiconductor device; as well as A control circuit outputs a control signal for controlling the drive circuit to the drive circuit.

9. A mobile object, characterized in that: Power control is performed using the power conversion device according to claim 8.

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