semiconductor device

Abstract

Semiconductor device comprising: a semiconductor chip (5); a housing (6) surrounding the semiconductor chip (5); a housing electrode (7) attached to an upper surface of the housing (6); a wire (8) connected to the semiconductor chip (5) and the housing electrode (7); a first holding part (10) securing the housing electrode (7) on the upper surface of the housing (6) outside a connecting part where the wire (8) is bonded to the housing electrode (7); and a second holding part (11) which secures the housing electrode (7) on the upper surface of the housing (6) within the connecting part, wherein a recess (12) is formed on the upper surface of the housing (6), the housing electrode (7) is bent into a U-shape so that it fits into the recess (12), the second holding part (11) is arranged in the recess (12) on a curved part of the housing electrode (7), the recess (12) is spaced from an inner end surface of the housing (6), and wherein a through hole (13) is formed in the bent part of the housing electrode (7).

Description

Area

[0001] The present invention relates to a semiconductor device in which a wire is bonded to a package electrode, and more particularly to a semiconductor device enabling a reduction in wire height. background

[0002] In semiconductor power conversion devices, wires are bonded to package electrodes using ultrasonic bonding or the like. For better wire bonding properties, the package electrodes must be firmly attached to the package. The prior art includes a design in which package electrodes are formed using insert molding or injection molding (see, for example, PTL 1: Embodiment 3, Fig. 25 to Fig. 28 or PTL 2: Embodiment 1, Fig. 5).

[0003] Further semiconductor devices are known from JP 2000-349219 A, JP 2000-332179 A and JP 2011-14739 A. Citation listPatent literature [PTL 1] JP 2009 - 021 286 A [PTL 2] JP 2009 - 130 007 A SummaryTechnical problem

[0004] Insert molding or injection molding of package electrodes does not secure the package electrodes firmly enough. Therefore, the package electrodes are held on both the inner and outer sides by wire connecting parts. However, this leads to the need to increase the wire height so that the wires do not touch a holding part that presses the package electrode down within the connecting part. If the wire is positioned highest among the structural components within the package, a sealing material must be poured to a height matching the wire height. This leads to the problem of increased thickness, weight, and cost of the semiconductor device.

[0005] The present invention has been made to solve the problem described above, and it is an object of the invention to provide a semiconductor device that enables a reduction in wire height while allowing wire bonding properties to be improved. Solution to the problem

[0006] This object is achieved by the features of the independent claim. The subclaims contain advantageous embodiments of the invention. A semiconductor device according to aspects of the present invention comprises: a semiconductor chip; a package surrounding the semiconductor chip; a package electrode attached to an upper surface of the package; a wire connected to the semiconductor chip and the package electrode; a first holding part that presses down the package electrode on the upper surface of the package outside a connecting part where the wire is bonded to the package electrode; and a second holding part that presses down the package electrode on the upper surface of the package inside the connecting part, wherein a recess is formed on the upper surface of the package, the package electrode is bent to fit into the recess, and the second holding part is arranged in the recess. Advantageous effects of the invention

[0007] In the present invention, the first holding part and the second holding part press down both ends of the case electrode and firmly fix the case electrode to the case. Consequently, the wire bonding properties can be improved. Furthermore, the second holding part is arranged in the recess on the upper surface of the case, so that the height of the upper surface of the second holding part is not higher than that of the upper surface of the case electrode outside the recess. Therefore, the height of the wire can be reduced. Short description of the drawings Fig. 1 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 1. Fig. 2 is a plan view illustrating a case electrode according to Comparative Example 1. Fig. 3 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 2. Fig. 4 is a cross-sectional view illustrating a semiconductor device according to Embodiment 1 of the present invention. Fig. 5 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 3. Fig. 6 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 4. Fig. 7 is a plan view illustrating a case electrode according to Comparative Example 4. Fig. 8 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 5. Fig. 9 is a plan view illustrating a case electrode according to Comparative Example 5. Fig. 10 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 6. Fig. 11 is a plan view and a cross-sectional view illustrating a case electrode according to Comparative Example 6. Fig. 12 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 7. Fig. 13 is a cross-sectional view illustrating a second holding part according to Comparative Example 7 on a larger scale. Fig. 14 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 8. Fig. 15 is a plan view illustrating a case electrode according to Comparative Example 8. Description of embodiments

[0008] A semiconductor device according to the embodiment of the present invention and a comparative example will be described with reference to the drawings. The same components are denoted by the same symbols, and repeated descriptions thereof will be omitted. Comparison example 1

[0009] Fig. 1 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 1. Fig. Figure 2 is a plan view illustrating a package electrode according to Comparative Example 1. A lower surface electrode 2 is provided on the lower surface of an insulating substrate 1, and a base plate 3 is provided on the upper surface of the substrate. A semiconductor chip 5 is provided on the base plate 3 via a solder 4.

[0010] A housing 6 surrounds the semiconductor chip 5 on the base plate 3. A housing electrode 7 is attached to an upper surface of the housing 6. A wire 8 is connected to the semiconductor chip 5 and the housing electrode 7. The semiconductor chip 5 and the wire 8 are sealed with a sealing material 9 within the housing 6.

[0011] A first holding part 10 presses down the case electrode 7 on the upper surface of the case 6 outside a connecting part where the wire 8 is bonded to the case electrode 7. A second holding part 11 presses down the case electrode 7 on the upper surface of the case 6 inside the connecting part. The first holding part 10 and the second holding part 11 are made of the same material as the case 6, namely, case resin.

[0012] A recess 12 is formed in an inner corner on the upper surface of the housing 6. The housing electrode 7 is bent to fit into the recess 12. The second holding part 11 is arranged in the recess 12. The upper surface of the second holding part 11 is positioned at a height not higher than that of the upper surface of the connecting part of the housing electrode 7.

[0013] Since the first holding part 10 and the second holding part 11 press down both ends of the housing electrode 7 and firmly secure the housing electrode 7 to the housing 6, the wire bonding properties can be improved. Since the second holding part 11 is arranged in the recess 12 on the upper surface of the housing 6 to keep the height of the upper surface of the second holding part 11 low, the height of the wire 8 can be reduced. This alleviates the limitations on the thickness of the semiconductor device and enables size reduction, as well as enabling weight and cost reduction. Comparison example 2

[0014] Fig. 3 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 2. The recess 12 is spaced outward from the inner end surface of the package 6. In this way, a certain length of creepage distance can be ensured between the semiconductor chip 5 and the package electrode 7. Other structures and effects are the same as those of Comparative Example 1. Embodiment 1

[0015] Fig. 4 is a cross-sectional view illustrating a semiconductor device according to Embodiment 1 of the present invention. A through-hole 13 is formed in a bent part of the package electrode 7. This allows the package resin to flow through the through-hole 13 to the second holding part 11 when the second holding part 11 is formed with the package resin. Other structures and effects are the same as those of Comparative Example 2. While the through-hole 13 is added to the configuration of Comparative Example 2 here, the through-hole 13 may be added to the configuration of Comparative Example 1. Comparison example 3

[0016] Fig. 5 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 3. In this Comparative Example, the case electrode 7 is ground to form a recess 14 in the upper surface of the case electrode 7. The second holding part 11 is disposed in the recess 14. In this way, the same effects as those of Comparative Example 1 can be achieved. Furthermore, compared with the bending process in Comparative Example 1, the processing accuracy of the case electrode 7 can be increased. Comparison example 4

[0017] Fig. 6 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 4. Fig. 7 is a plan view illustrating a can electrode according to Comparative Example 4. The recess 14 is a through hole that gradually reduces in width downward. The second holding part 11 only needs to be placed in the recess 14 of each can electrode 7 and does not need to be provided between adjacent can electrodes 7. Thus, the amount of resin used for the second holding part 11 can be reduced. Other structures and effects are the same as those of Comparative Example 2. Comparison example 5

[0018] Fig. 8 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 5. Fig. 9 is a plan view illustrating a housing electrode according to Comparative Example 5. The recess 14 is a through-hole with a trapezoidal cross-sectional shape. Therefore, machining is easy. Other structures and effects are the same as those of Comparative Example 4. Comparison example 6

[0019] Fig. 10 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 6. Fig. 11 is a plan view and a cross-sectional view illustrating a can electrode according to Comparative Example 6. The can electrode 7 has an H-shaped cross section with recesses 15 in the side surfaces. By filling the can resin into the recesses 15, the can electrode 7 is fixed to the can 6. Since the can electrode 7 is firmly fixed to the can 6 in this way, the wire bonding properties can be improved. Since the second holding part 11 does not need to be provided on the can electrode 7, the height of the wire 8 can also be reduced. Comparison example 7

[0020] Fig. 12 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 7. Fig. 13 is a cross-sectional view illustrating a second holding part according to Comparative Example 7 of the present invention on a larger scale. As in Comparative Example 1, the first holding part 10 and the second holding part 11 press down both ends of the case electrode 7 to firmly fix the case electrode 7 to the case 6, so that the wire bonding properties can be improved.

[0021] In this comparative example, the second holding part 11 is chamfered along the wire 8. The second holding part 11 is ground into a chamfered shape to avoid the wire 8, thereby ensuring a certain distance between the second holding part 11 and the wire 8. This allows the height of the wire 8 to be reduced without changing the structure of the housing electrode 7. Comparative example 8

[0022] Fig. 14 is a cross-sectional view illustrating a semiconductor device according to Comparative Example 8. Fig. 15 is a plan view illustrating a case electrode according to Comparative Example 8. As in Comparative Example 1, the first holding part 10 and the second holding part 11 press down both ends of the case electrode 7 to firmly fix the case electrode 7 to the case 6, so that the wire bonding properties can be improved.

[0023] If the second holding part 11 is formed from the same resin material as that of the housing 6 so as to extend over the electrodes, it will end up having a large height. Therefore, in this comparative example, the second holding part 11 is formed by applying an adhesive. This allows the height of the second holding part 11 to be reduced without changing the structure of the housing electrode 7.

[0024] The semiconductor chip 5 is a MOSFET, an SBD, an IGBT, a PN diode, or the like. The semiconductor chip 5 is not limited to a semiconductor chip formed of silicon, but may instead be made of a wide-bandgap semiconductor having a wider bandgap than that of silicon. The wide-bandgap semiconductor is, for example, silicon carbide, a gallium nitride-based material, or diamond. A semiconductor chip 5 formed of such a wide-bandgap semiconductor has high withstand voltage and high allowable current density and can thus be miniaturized. The use of such a miniaturized semiconductor chip 5 enables miniaturization and high integration of the semiconductor device in which the semiconductor chip 5 is integrated.Furthermore, since the semiconductor chip 5 has high heat resistance, a radiating fin of a heat sink can be miniaturized, and a water-cooled part can be air-cooled, leading to further miniaturization of the semiconductor device. Furthermore, since the semiconductor chip 5 has low power loss and high efficiency, a high-efficiency semiconductor device can be achieved. List of reference symbols

[0025] 5 semiconductor chip; 6 housing; 7 housing electrode; 8 wire; 10 first holding part; 11 second holding part; 12, 14, 15 recess; 13 through hole

Claims

[1] A semiconductor device comprising: a semiconductor chip (5); a housing (6) surrounding the semiconductor chip (5); a housing electrode (7) attached to an upper surface of the housing (6); a wire (8) connected to the semiconductor chip (5) and the housing electrode (7); a first holding part (10) securing the housing electrode (7) on the upper surface of the housing (6) outside a connecting part where the wire (8) is bonded to the housing electrode (7); and a second holding part (11) which secures the housing electrode (7) on the upper surface of the housing (6) within the connecting part, wherein a recess (12) is formed on the upper surface of the housing (6), the housing electrode (7) is bent into a U-shape so that it fits into the recess (12), the second holding part (11) is arranged in the recess (12) on a curved part of the housing electrode (7), the recess (12) is spaced from an inner end surface of the housing (6), and wherein a through hole (13) is formed in the bent part of the housing electrode (7). [2] The semiconductor device according to claim 1, wherein an upper surface of the second holding part (11) is positioned at a height not higher than a height of an upper surface of the connecting part of the housing electrode (7). [3] A semiconductor device according to claim 1 or 2, wherein the semiconductor chip (5) is made of a wide band gap semiconductor.

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