Semiconductor device

Abstract

A semiconductor device according to one embodiment includes a semiconductor element, a first conductor, a first electrode, a second conductor, a second electrode, and a cover.　The semiconductor element extends over a first plane, and includes a first surface, a second surface opposing the first surface, and a third surface spanning between an end of the first surface and an end of the second surface. The semiconductor element includes a first electrode pad provided in a region including the first surface, and a second electrode pad provided in a region including the second surface.　The first conductor is in contact with the first electrode pad.　The first electrode is in contact with the first conductor.　The second conductor is in contact with the second electrode pad.　The second electrode is in contact with the second conductor.　The cover is a resin cover including a first portion, a second portion, and a third portion.　The first portion covers the third surface.　The second portion is connected to the first portion and faces the first surface.　The third portion is connected to the first portion, faces the second surface, and sandwiches the semiconductor element together with the second portion.

Description

Semiconductor Devices

[0001] FIELD An embodiment of the present invention relates to a semiconductor device.

[0002] Known power semiconductor devices include an insulated gate bipolar transistor (IGBT) and an injection enhanced gate transistor (IEGT). The chips of these semiconductor devices include a collector electrode pad on one of two opposing surfaces and an emitter electrode pad on the other. Electrodes are attached to each of the collector electrode pad and the emitter electrode pad. Since high voltages are applied to power semiconductor devices, they are required to be able to withstand such high voltages.

[0003] International Publication No. 2012 / 133098 Pamphlet Japanese Patent Application Laid-Open No. 6-224235 Japanese Patent No. 7203214

[0004] A semiconductor device having high breakdown voltage is provided.

[0005] A semiconductor device according to one embodiment includes a semiconductor element, a first conductor, a first electrode, a second conductor, a second electrode, and a cover. The semiconductor element extends along a first surface and includes a first surface, a second surface opposite the first surface, and a third surface extending from an end of the first surface to an end of the second surface. The semiconductor element also includes a first electrode pad provided in a region including the first surface and a second electrode pad provided in a region including the second surface. The first electrode contacts the first conductor. The second conductor contacts the second electrode pad. The second electrode contacts the second conductor. The cover is a resin cover including a first portion, a second portion, and a third portion. The first portion covers the third surface. The second portion is connected to the first portion and faces the first surface. The third portion is connected to the first portion, faces the second surface, and sandwiches the semiconductor element together with the second portion.

[0006] FIG. 1 shows an example of the structure of a conversion device including the semiconductor device of the first embodiment. FIG. 2 shows an example of the cross-sectional structure of a semiconductor module including the semiconductor device of the first embodiment. FIG. 3 shows an example of the planar structure of the semiconductor device of the first embodiment. FIG. 4 shows an example of the planar structure of the semiconductor device of the first embodiment. FIG. 5 shows an example of the cross-sectional structure of the semiconductor device of the first embodiment. FIG. 6 shows an example of the cross-sectional structure of the semiconductor device of the first embodiment. FIG. 7 shows an example of the cross-sectional structure of the semiconductor device of the first embodiment. FIG. 8 shows a part of the manufacturing process of the semiconductor device of the first embodiment. FIG. 9 shows a part of the manufacturing process of the semiconductor device of the first embodiment. FIG. 10 shows an example of the cross-sectional structure of a semiconductor device of a modified example of the first embodiment. Embodiment

[0007] The following embodiments will be described with reference to the drawings. The drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. may differ from the actual ones. Furthermore, the drawings may include portions in which the relationship and ratio of dimensions differ from each other.

[0008] Hereinafter, embodiments will be described using an XYZ Cartesian coordinate system. The positive direction of the vertical axis of a diagram may be referred to as the upper side, and the negative direction as the lower side. The positive direction of the horizontal axis of a diagram may be referred to as the right side, and the negative direction as the left side. That is, in a plan view showing the XY plane (XY plane view (hereinafter the same)), the upper side indicates the +Y direction, the lower side indicates the -Y direction, the right side indicates the +X direction, and the left side indicates the -X direction. In an XZ plane view observed in the +Y direction, the upper side indicates the +Z direction, the lower side indicates the -Z direction, the right side indicates the +X direction, and the left side indicates the -X direction.

[0009] 1. First Embodiment 1.1. Configuration (Structure) FIG. 1 shows an example of the structure of a conversion device including a semiconductor device according to the first embodiment. The conversion device 100 converts, for example, electric power. As shown in FIG. 1, the conversion device 100 includes a housing including a bottom 101, a side 102, and a top 103. The housing has a space therein. The conversion device 100 also includes, inside the housing, a support 105, a plurality of cooling fins 106, a support 107, a spring 108, and a plurality of semiconductor modules 110. FIG. 1 shows an example of three semiconductor modules 110.

[0010] The support 105 is made of an insulator and is located on the upper surface of the bottom 101. A plurality of cooling fins 106 and a plurality of semiconductor modules 110 are alternately located on the upper surface of the support 105. That is, one semiconductor module 110 is placed on the upper surface of one cooling fin 106, another cooling fin is placed on the upper surface of the semiconductor module 110, and similarly, further semiconductor modules 110 and cooling fins 106 are placed. Two semiconductor modules 110 aligned in the +Z direction are electrically connected.

[0011] The support 107 is made of an insulating pair and is located on the upper surface of the uppermost cooling fin 106. The spring 108 is located on the upper surface of the support 107 and is in contact with the lower surface of the upper part 103 at its upper surface.

[0012] 2 shows an example of a cross-sectional structure of a semiconductor module including the semiconductor device of the first embodiment. As shown in FIG. 2, the semiconductor module 110 includes a plurality of semiconductor devices 1, a plurality of conductors 131, a plurality of terminal boards 132, and external electrodes 135 and 136.

[0013] The plurality of semiconductor devices 1 are arranged at intervals on the upper surface of the external electrode 135. The semiconductor device 1 includes a semiconductor element 3, an emitter electrode 4, and a collector electrode 5.

[0014] The semiconductor element 3 is an element formed on a substrate substantially composed of a semiconductor. In this specification, the term "substantially" means that the degree of the content expressed by the term "substantially" does not require strict literal adherence, but includes errors due to unavoidable factors. Examples of the semiconductor element 3 include an IGBT and an IEGT.

[0015] The collector electrode 5 is a conductive member such as a metal, and is located on the upper surface of the external electrode 135. The semiconductor element 3 is located on the upper surface of the collector electrode 5.

[0016] The emitter electrode 4 is a conductive member such as a metal, and is located on the upper surface of the semiconductor element 3.

[0017] The conductor 131 is located on the upper surface of the semiconductor element 3, and its lower surface contacts the gate electrode pad 6 (not shown) of the semiconductor element 3. The terminal plate 132 has its lower surface contacting the upper surface of the conductor 131.

[0018] The external electrode 135 contains copper (Cu) or is substantially made of copper. The lower surface of the external electrode 136 contacts the upper surfaces of the plurality of semiconductor elements 3. The external electrode 136 contains copper or is substantially made of copper.

[0019] 3 and 4 show an example of the planar structure of the semiconductor device of the first embodiment. Fig. 3 shows the semiconductor device 1 observed in the -Z direction. Fig. 4 shows the semiconductor device 1 observed in the +Z direction.

[0020] 3 and 4, the semiconductor device 1 extends along the XY plane. The semiconductor element 3 has a quadrilateral shape, for example, a rectangular shape, along the XY plane. In addition to including the semiconductor element 3, emitter electrode 4, and collector electrode 5 as described above with reference to FIG. 2, the semiconductor device 1 also includes a cover 7. The semiconductor element 3 further includes a gate electrode pad 6.

[0021] The emitter electrode 4 has a size that fits within the edge of the semiconductor element 3 along the XY plane. The emitter electrode 4 has a quadrilateral shape with the corners of the quadrilateral cut out along the XY plane. The emitter electrode 4 has, for example, a rectangular shape with the corners of the rectangle cut out along the XY plane. The emitter electrode 4 contacts an emitter electrode pad 31 (not shown) of the semiconductor element 3.

[0022] The emitter electrode 4 includes one or more of molybdenum (Mo), ruthenium (Ru), tungsten (W), iron (Fe), copper (Cu), cobalt (Co), nickel (Ni), and palladium (Pd). The emitter electrode 4 includes molybdenum, copper molybdenum, copper tungsten, or invar as a main material, or is essentially composed of molybdenum, copper molybdenum, copper tungsten, or invar.

[0023] As described above with reference to FIG. 1 , the semiconductor device 1 may be included in a semiconductor module 110, and multiple semiconductor modules 110 may be stacked in the conversion device 100. In such applications, the semiconductor device 1 is subjected to a large load. To withstand this load, molybdenum, copper molybdenum, copper tungsten, or invar is used. Molybdenum, copper molybdenum, copper tungsten, and invar have high hardness.

[0024] When molybdenum is used, the surface of the emitter electrode 4 may be coated with one or more of nickel, gold (Au), palladium (Pd), and ruthenium (Ru).

[0025] Copper molybdenum is an alloy of copper and molybdenum. Copper tungsten is an alloy of copper and tungsten. Copper molybdenum and copper tungsten have higher heat dissipation properties and are less susceptible to thermal expansion than molybdenum.

[0026] Invar has a lower thermal expansion than molybdenum. When Invar is used, the emitter electrode 4 contains iron and cobalt, or iron and nickel.

[0027] The collector electrode 5 has a size that fits inside the edge of the semiconductor element 3 along the XY plane. The collector electrode 5 has a quadrilateral shape, for example, a rectangular shape, along the XY plane. The emitter electrode 4 contacts the collector electrode pad 32 of the semiconductor element 3. The collector electrode 5 is made of substantially the same material as the material that can be used for the emitter electrode 4.

[0028] The gate electrode pad 6 is a conductive member such as a metal. The gate electrode pad 6 is located in a notch in the emitter electrode 4. The gate electrode pad 6 has a quadrilateral shape, for example, a rectangular shape, along the XY plane. The gate electrode pad 6 is spaced apart from the emitter electrode 4.

[0029] The cover 7 is an insulating member. The cover 7 has an annular shape along the XY plane and a quadrilateral outline, for example, a rectangular outline. The cover 7 is positioned around the semiconductor element 3 and extends continuously along the edge of the semiconductor element 3. The cover 7 is substantially made of insulating resin. Examples of resin include PTFE (polytetrafluoroethylene).

[0030] Fig. 5 shows an example of a cross-sectional structure of the semiconductor device of the first embodiment. Fig. 5 shows the structure taken along line V-V in Fig. 3 and Fig. 4, and shows the cross-sectional structure taken along the XZ plane. The semiconductor device 1 has the structure shown in Fig. 5 in any XZ plane and any YZ plane not including the gate electrode pad 6, for example.

[0031] 5, the semiconductor device 1 further includes conductors 11 and 12 and insulators 14 and 15. Fig. 5 also shows an emitter electrode pad 31 and a collector electrode pad 32 of the semiconductor element 3. The dimensions and positional relationships of some of the components shown in Fig. 5 will be described later with reference to Fig. 6.

[0032] The emitter electrode pad 31 extends along the XY plane and also extends over an area including one of the two opposing surfaces of the semiconductor element 3. Fig. 5 shows an example in which the emitter electrode pad 31 is located on the upper surface of the two opposing surfaces.

[0033] The collector electrode pad 32 faces the emitter electrode pad 31. The collector electrode pad 32 extends along the XY plane and also extends along the XY plane of the semiconductor element 3, and also extends over an area including the other of the two opposing surfaces. Fig. 5 shows an example in which the collector electrode pad 32 is located on the lower of the two opposing surfaces.

[0034] The emitter electrode 4 has a rectangular parallelepiped shape with the corners cut off to form a rectangular parallelepiped. The emitter electrode 4 faces the surface of the semiconductor element 3 on which the emitter electrode pad 31 is located, via the conductor 11. The emitter electrode 4 has a length L1 in the X direction.

[0035] The collector electrode 5 has a rectangular parallelepiped shape and faces the surface of the semiconductor element 3 on which the collector electrode pad 32 is located, via the conductor 12. The collector electrode 5 has a length L2 in the X direction. The length L2 is longer than the length L1.

[0036] The conductor 11 extends along the XY plane. The conductor 11 is located between the emitter electrode pad 31 and the emitter electrode 4, and is in contact with the upper surface of the emitter electrode pad 31 and the lower surface of the emitter electrode 4. The edge of the conductor 11 is located closer to the center line CL of the semiconductor device 1 than the edge of the emitter electrode 4.

[0037] Examples of the conductor 11 include metals, such as a sintered metal body. The sintered body is formed by heating and sintering a sheet or paste containing the material of the conductor 11. The conductor 11 is substantially made of a material that easily bonds with the emitter electrode 4 based on the material of the emitter electrode 4. The conductor 11 is substantially made of a metal, and includes one or more of gold, silver (Ag), copper, lead (Pb), tin (Sn), and nickel. The conductor 11 contains gold, silver, copper, or solder as a main material, or is substantially made of gold, silver, copper, or solder.

[0038] Gold is resistant to oxidation and therefore easily bonds to many metals, and has higher electrical conductivity and heat dissipation than solder. Silver can be handled using common techniques, is relatively easy to obtain, and has higher electrical conductivity and heat dissipation than solder. Copper has high heat dissipation properties, is easily obtained, and has higher electrical conductivity and heat dissipation than solder. Solder is easily obtainable and can be handled using common techniques.

[0039] The conductor 12 extends along the XY plane. The conductor 12 is located between the collector electrode pad 32 and the collector electrode 5, and is in contact with the upper surface of the collector electrode 5 and the lower surface of the collector electrode pad 32. The edge of the conductor 12 is located closer to the center line CL of the semiconductor device 1 than the edge of the collector electrode 5. The conductor 12 is formed by heating and sintering a sheet or paste containing the material of the conductor 12. Examples of the conductor 12 include metals, such as sintered metals. The conductor 12 is substantially made of metal, and is substantially made of the same material as the material that can be used for the conductor 11.

[0040] The insulator 14 surrounds the conductor 11 along the XY plane, is located between the emitter electrode 4 and the upper surface of the semiconductor element 3, and is in contact with the lower surface of the emitter electrode 4 and the upper surface of the semiconductor element 3. The insulator 14 is also partially located between the upper surface of the semiconductor element 3 and the cover 7, and covers the upper surface of the semiconductor element 3 except for the area directly below the emitter electrode 4 and the area above the gate electrode pad 6. The insulator 14 is substantially composed of a heat-resistant organic material. For example, the insulator 14 may contain or substantially consist of a component contained in a solvent of a paste or sheet containing elements of the conductor 11. An example of the component is propylene carbonate.

[0041] The insulator 15 surrounds the conductor 12 along the XY plane, is located between the collector electrode 5 and the lower surface of the semiconductor element 3, and is in contact with the upper surface of the collector electrode 5 and the lower surface of the semiconductor element 3. The insulator 15 is made of substantially the same material as the material that can be used as the insulator 14.

[0042] The cover 7 covers the upper surface of the semiconductor element 3 except for the region directly below the emitter electrode 4 and the region above the gate electrode pad 6. The cover 7 also covers the lower surface of the semiconductor element 3 in a region that is not covered by either the insulator 15 or the collector electrode 5. The cover 7 also covers the entire side surface of the semiconductor element 3.

[0043] 6 shows an example of a cross-sectional structure of the semiconductor device of the first embodiment. Fig. 6 shows the structure taken along line VI-VI in Fig. 3 and Fig. 4, and shows the cross-sectional structure taken along the XZ plane. The semiconductor device 1 has the structure shown in Fig. 6 in any XZ plane and any YZ plane including the gate electrode pad 6, for example.

[0044] 6 and as described above with reference to Fig. 4, the gate electrode pad 6 is located in the notched portion of the emitter electrode 4. The gate electrode pad 6 is located in a region including the upper surface of the semiconductor element 3. The gate electrode pad 6 is not covered by the cover 7 and is exposed.

[0045] FIG. 7 shows an example of the cross-sectional structure of the semiconductor device of the first embodiment, showing an enlarged portion of the side surface of the semiconductor device 1. As shown in FIG. 7, there is a distance D1 between the edge of the collector electrode 5 and the side surface of the semiconductor element 3. There is a distance D2 between the edge of the emitter electrode 4 and the side surface of the semiconductor element 3. Distance D2 is greater than distance D1. This is for the following reason: while the semiconductor element 3 is operating (while voltages are applied to the emitter electrode 4 and the collector electrode 5), the potential of the collector electrode 5 is transmitted from the corner of the collector electrode 5 to the side surface of the semiconductor element 3, and the area along and nearby the side surface of the semiconductor element 3 has the same potential as the collector electrode 5. Therefore, point A near the corner formed by the top surface and side surface of the semiconductor element 3 has the same potential as the collector electrode 5. Therefore, if the emitter electrode 4 is close to point A, a discharge may occur between point A and the emitter electrode 4. To avoid this, the emitter electrode 4 is located away from point A, and therefore distance D2 is greater than distance D1.

[0046] The cover 7 includes a first portion 71 , a second portion 72 , a third portion 73 , a fourth portion 74 , and a fifth portion 75 .

[0047] The first portion 71 has a quadrilateral shape. The first portion 71 occupies an area including the entire side surface of the cover 7. The first portion 71 covers the entire side surface of the semiconductor element 3. The first portion 71 extends from the upper end to the lower end of the cover 7.

[0048] The second portion 72 has a quadrilateral shape. The second portion 72 occupies a region of the cover 7 between the first portion 71 and the collector electrode 5. The second portion 72 is located in a region including a portion of the lower end of the cover 7. The left side surface (the side closer to the center line CL of the semiconductor device 1) of the second portion 72 contacts the side surface of the collector electrode 5. The upper edge of the second portion 72 is aligned with the upper surface of the collector electrode 5. The right side edge (the side farther from the center line CL of the semiconductor device 1) of the second portion 72 is connected to the left side edge (the side closer to the center line CL of the semiconductor device 1) of the first portion 71. The length of the second portion 72 in the X direction, i.e., the distance D1, is based on a dimension determined so that the second portion 72 covers a maximum of 5% of the lower surface of the semiconductor element 3.

[0049] The third portion 73 has a quadrilateral shape. The third portion 73 occupies a region of the cover 7 between the first portion 71 and the emitter electrode 4. The third portion 73 is located in a region including a portion of the upper end of the cover 7. The left side surface of the third portion 73 (the side closer to the center line CL of the semiconductor device 1) contacts the side surface of the emitter electrode 4. The lower edge of the third portion 73 is located in the −Z direction from the lower surface of the emitter electrode 4. The right side edge of the third portion 73 (the side farther from the center line CL of the semiconductor device 1) is connected to the left side edge of the first portion 71 (the side closer to the center line CL of the semiconductor device 1). The length of the third portion 73 in the X direction, i.e., the distance D2, is based on a dimension determined so that the third portion 73 covers a maximum of 20% of the upper surface of the semiconductor element 3.

[0050] The fourth portion 74 occupies a region of the cover 7 between the second portion 72 and the semiconductor element 3, and a region between the collector electrode 5 and the semiconductor element 3. The fourth portion 74 has a quadrilateral shape. The lower edge of the fourth portion 74 is connected to the upper edge of the second portion 72. The right edge of the fourth portion 74 (the side farther from the center line CL of the semiconductor device 1) is connected to the left edge of the first portion 71 (the side closer to the center line CL of the semiconductor device 1).

[0051] The fifth portion 75 occupies a region of the cover 7 between the third portion 73 and the semiconductor element 3. The fifth portion 75 has a quadrilateral shape. The upper edge of the fifth portion 75 is connected to the lower edge of the third portion 73. The right edge of the fifth portion 75 (the side farther from the center line CL of the semiconductor device 1) is connected to the left edge of the first portion 71 (the side closer to the center line CL of the semiconductor device 1).

[0052] The cover 7 covers the upper surface of the semiconductor element 3 except for the portion not covered by the emitter electrode 4 and the portion above the gate electrode pad 6. The cover 7 covers the lower surface of the semiconductor element 3 except for the portion not covered by the collector electrode 5.

[0053] The cover 7 sandwiches the upper and lower surfaces of the semiconductor element 3 between a first portion 71, a second portion 72, and a third portion 73. Due to the shape of the cover 7, the cover 7 is fixed to the semiconductor element 3 without using adhesive.

[0054] 8 and 9 show a part of the manufacturing process of the semiconductor device of the first embodiment. Fig. 9 shows the state before the collector electrode 5, the bonding material 21, the semiconductor element 3, the bonding material 22, the emitter electrode 4, the resin 7A, the jig 25, and the buffer material 26 are stacked.

[0055] 8 and 9 , the collector electrode 5, bonding material 21, semiconductor element 3, bonding material 22, emitter electrode 4, and buffer material 26 are stacked in this order in the +Z direction within the opening of the mask 27. The cross section of the mask 27 has a rectangular shape with an inner corner cut out into a rectangular shape. The bottom end of the cutout is approximately aligned with the top surface of the semiconductor element 3.

[0056] The bonding material 21 contains the conductor 12 and the insulator 15 as a solvent, and has the form of a sheet or paste. The bonding material 22 contains the conductor 11 and the insulator 14 as a solvent, and has the form of a sheet or paste.

[0057] Resin 7A is placed on the top surface of semiconductor element 3. Resin 7A is a material that will become cover 7 by sintering. Resin 7A has an annular shape and has an opening that is larger than the shape of emitter electrode 4 along the XY plane. Resin 7A is placed on the top surface of semiconductor element 3 so as to enclose emitter electrode 4 within its opening.

[0058] A jig 25 is placed on the upper surface of the resin 7A. The jig 25 fixes the position of the resin 7A. The jig 25 has an annular shape and has an opening that is larger than the shape of the emitter electrode 4 along the XY plane. The jig 25 is placed on the upper surface of the resin 7A so as to enclose the emitter electrode 4 within its opening.

[0059] A buffer material 26 is disposed on the upper surface of the emitter electrode 4. The buffer material 26 is made of, for example, substantially the same material as the material of the cover 7.

[0060] With the collector electrode 5, bonding material 21, semiconductor element 3, bonding material 22, emitter electrode 4, resin 7A, jig 25, and buffer material 26 arranged as described above within the opening of mask 27, the upper surface of buffer material 26 is subjected to pressure by punch 29. With pressure applied, the structure consisting of collector electrode 5, bonding material 21, semiconductor element 3, bonding material 22, emitter electrode 4, resin 7A, jig 25, and buffer material 26 is heated.

[0061] The bonding material 21 is sintered by heating while being pressurized, forming the conductor 12, which bonds the semiconductor element 3 and the collector electrode 5 together. The solvent in the bonding material 21 diffuses, forming the insulator 15.

[0062] The bonding material 22 is sintered by heating while being pressurized. As a result, the conductor 11 is formed, and the semiconductor element 3 and the emitter electrode 4 are bonded via the conductor 11. Furthermore, the solvent in the bonding material 22 diffuses to form the insulator 14. Because the area of ​​the XY plane of the emitter electrode 4 is smaller than the area of ​​the XY plane of the collector electrode 5, the emitter electrode 4 is subjected to a greater pressure than the collector electrode 5. Therefore, the solvent in the bonding material 22 spreads over a wider area than the solvent in the bonding material 21.

[0063] The resin 7A deforms and spreads due to heating while being pressurized. As a result, the resin 7A moves through the region between the mask 27 and the semiconductor element 3, and further reaches the region between the semiconductor element 3 and the collector electrode 5. In this way, the cover 7 is formed from the resin 7A. Even if a portion of the surface of the semiconductor element 3 is formed that does not come into contact with the cover 7, the region between the surface of the semiconductor element 3 and the cover 7 at that portion is filled with the solvent of the bonding material 21 or 22, i.e., the insulator 15 or 16. Therefore, the portion of the surface of the semiconductor element 3 that does not come into contact with the cover 7 is covered with the insulator 14 or 15.

[0064] After applying pressure and heat, the semiconductor device 1 is completed by cleaning and hardening the cover 7 .

[0065] After hardening, the semiconductor device 1 may be heated, which softens the cover 7 and more reliably fills the area between the cover 7 and the semiconductor element 3, the emitter electrode 4, or the collector electrode 5 before softening.

[0066] According to the first embodiment, as will be described below, it is possible to provide a semiconductor device 1 having a high breakdown voltage.

[0067] During the same pressure and heat application process described above with reference to Figure 8, the bonding material, and therefore its constituent conductors, may protrude from the emitter or collector electrodes in the plane along the XY plane, which may cause discharge between the collector and emitter electrodes.

[0068] According to the first embodiment, the semiconductor device 1 includes an insulating cover 7 that covers the side surfaces of the semiconductor element 3 and has a shape that sandwiches the upper and lower surfaces of the semiconductor element 3. This suppresses protrusion of the conductors 11 and 12, thereby suppressing discharge between the collector electrode 5 and the emitter electrode 4 that would be caused by the protrusion of the conductors 11 or 12. This allows the semiconductor device 1 to have a high breakdown voltage.

[0069] According to the first embodiment, the cover 7 covers the portion of the upper surface of the semiconductor element 3 that is not covered by the emitter electrode 4, and also covers the portion of the lower surface of the semiconductor element 3 that is not covered by the collector electrode 5. Thus, the cover 7 covers the area from the end of the collector electrode 5 to the end of the emitter electrode 4. This coverage by the cover 7 improves the insulation of the region between the collector electrode 5 and the emitter electrode 4, and enables the semiconductor device 1 to have a high breakdown voltage.

[0070] The semiconductor device 1 includes insulators 14 and 15, and the insulator 14 partially fills the gap between the cover 7 and the semiconductor element 3 and partially covers the top surface of the semiconductor element 3. The insulators 14 and 15 are derived from a solvent, i.e., a liquid, and fill the gap between the cover 7 and the semiconductor element 3 with high precision. Therefore, the region between the end of the collector electrode 5 and the end of the emitter electrode 4 is covered with the cover 7 and the insulators 14 and 15 with high precision. This contributes to realizing a semiconductor device 1 with high breakdown voltage.

[0071] The semiconductor device 1 does not use adhesive to secure the cover 7 and the semiconductor element 3. In some cases, an insulating chip frame is attached to surround the semiconductor element to improve the voltage resistance of the semiconductor element. This attachment can be performed using adhesive. However, components of the adhesive, such as siloxane, can deteriorate the characteristics of the semiconductor element. Because the semiconductor device 1 does not use adhesive to secure the cover 7 and the semiconductor element 3, deterioration of the characteristics of the semiconductor element 3 due to the adhesive is suppressed.

[0072] 1.3 Modifications As shown in Fig. 10, the cover 7 may cover the entire side surface of the semiconductor element 3, only the vicinity of the edge of the upper surface of the semiconductor element 3, and only the vicinity of the edge of the lower surface of the semiconductor element 3. Such a shape of the cover 7 can be produced when the pressure and / or temperature in the pressurizing and compressing step described above with reference to Fig. 8 is lower than the pressure and / or temperature used in the step of Fig. 8. Even with the structure shown in Fig. 10, a high breakdown voltage can be achieved because the side surface of the semiconductor element 3, which significantly contributes to the generation of discharge between the collector electrode 5 and the emitter electrode 4, is covered with the cover 7.

[0073] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention described in the claims and their equivalents.

Claims

1. A semiconductor element extending along a first surface, including a first surface, a second surface opposite the first surface, and a third surface spanning an end of the first surface and an end of the second surface, a first electrode pad provided in an area including the first surface, and a second electrode pad provided in an area including the second surface; a first conductor in contact with the first electrode pad, a first electrode in contact with the first conductor, a second conductor in contact with the second electrode pad, and a second electrode in contact with the second conductor; and an insulating cover including a first portion, a second portion, and a third portion, wherein the first portion covers the third surface, the second portion is connected to the first portion and faces the first surface, and the third portion is connected to the first portion and faces the second surface, and the cover and the second portion sandwich the semiconductor element therebetween.

2. The semiconductor device according to claim 1, wherein said cover is continuous over an area facing said first surface, an area facing said second surface, and an area facing said third surface.

3. The semiconductor device according to claim 1, wherein the cover continuously surrounds the periphery of the semiconductor element along the first surface.

4. The semiconductor device of claim 1, further comprising: a first insulator on the first surface; and a second insulator on the second surface, wherein the second portion of the cover includes a portion not in contact with the first surface, the first insulator being located between the first surface and the portion of the second portion of the cover not in contact with the first surface, the third portion of the cover includes a portion not in contact with the second surface, and the second insulator being located between the second surface and the portion of the second portion of the cover not in contact with the second surface.

5. The semiconductor device according to claim 1, wherein the second portion of the cover contacts the first electrode, and the third portion of the cover contacts the second electrode.

6. The semiconductor device according to claim 1, wherein one or both of the first electrode and the second electrode comprises one or more of molybdenum, ruthenium, tungsten, iron, copper, cobalt, nickel, and palladium.

7. The semiconductor device according to claim 1, wherein one or both of the first conductor and the second conductor include one or more of gold, silver, copper, lead, tin, and nickel.

8. The semiconductor device according to claim 2, wherein one or both of the first electrode and the second electrode include one or more of molybdenum, ruthenium, tungsten, iron, copper, cobalt, nickel, and palladium.

9. The semiconductor device according to claim 2, wherein one or both of the first conductor and the second conductor include one or more of gold, silver, copper, lead, tin, and nickel.

10. The semiconductor device according to claim 3, wherein one or both of the first electrode and the second electrode comprises one or more of molybdenum, ruthenium, tungsten, iron, copper, cobalt, nickel, and palladium.

11. The semiconductor device according to claim 3, wherein one or both of the first conductor and the second conductor include one or more of gold, silver, copper, lead, tin, and nickel.

12. The semiconductor device according to claim 4, wherein one or both of the first electrode and the second electrode comprises one or more of molybdenum, ruthenium, tungsten, iron, copper, cobalt, nickel, and palladium.

13. The semiconductor device according to claim 4, wherein one or both of the first conductor and the second conductor include one or more of gold, silver, copper, lead, tin, and nickel.

Images