JP2019096810A - Semiconductor device - Google Patents

Abstract

To provide a semiconductor device capable of being downsized and having an explosion-proof structure.SOLUTION: A semiconductor device comprises: a first metal member; a second metal member arranged adjacent to the first metal member; at least two semiconductor elements arranged in parallel between the first metal member and the second metal member; and a resin member filled between the first metal member and the second metal member and sealing the semiconductor elements. The semiconductor elements are electrically connected to the first metal member via a first joining member, and electrically connected to the second metal member via a second joining member. The resin member includes a first portion provided between the semiconductor elements, and a second portion surrounding the outside of the semiconductor elements. Intensity of the first portion is lower than intensity of the second portion.SELECTED DRAWING: Figure 1

Description

  Embodiments relate to a semiconductor device.

  There is a power converter which has a structure in which a plurality of semiconductor devices are connected in series and which controls a power of several megawatts. Such a power converter has redundancy such that power control can be continued by the remaining semiconductor devices even if one of the plurality of semiconductor devices has a short circuit failure. However, the power control function can not be maintained when a short-circuit failure that leads to an explosive failure of the semiconductor device occurs. For this reason, although the semiconductor device of the explosion-proof structure which pressure-contacted the semiconductor element between two conductors and sealed in the inside of a ceramic-made envelope is used, it is difficult to achieve size reduction and cost reduction.

Patent No. 3258200 Patent No. 4385324 Patent No. 4292686

  The embodiment provides a semiconductor device having an explosion-proof structure that can be miniaturized and reduced in cost.

  The semiconductor device according to the embodiment is disposed in parallel between a first metal member, a second metal member disposed in proximity to the first metal member, and the first metal member and the second metal member. And at least two semiconductor elements, and a resin member filled between the first metal member and the second metal member and sealing the semiconductor element. The semiconductor element is electrically connected to the first metal member via a first bonding member, and is electrically connected to the second metal member via a second bonding member. The resin member includes a first portion provided between the semiconductor elements and a second portion surrounding the outside of the semiconductor element, and the strength of the first portion is greater than the strength of the second portion. Low.

It is a schematic cross section showing the semiconductor device concerning an embodiment. It is a schematic cross section showing a semiconductor module concerning an embodiment. It is a schematic cross section which shows the short circuit state of the semiconductor module concerning embodiment. It is a schematic cross section which shows the semiconductor module concerning the modification of an embodiment. It is a schematic cross section which shows the semiconductor module concerning another modification of an embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. The same parts in the drawings are denoted by the same reference numerals, and the detailed description thereof will be omitted as appropriate, and different parts will be described. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the ratio of sizes between parts, and the like are not necessarily the same as the actual ones. In addition, even in the case of representing the same portion, the dimensions and ratios may be different from one another depending on the drawings.

  Furthermore, the arrangement and configuration of each part will be described using the X-axis, Y-axis and Z-axis shown in each drawing. The X axis, the Y axis, and the Z axis are orthogonal to one another, and represent the X direction, the Y direction, and the Z direction, respectively. Further, the Z direction may be described as upper, and the opposite direction as lower.

  FIG. 1 is a schematic cross-sectional view showing a semiconductor device 1 according to the embodiment. The semiconductor device 1 includes a base plate 10, a wiring plate 20, and a plurality of semiconductor modules SM. The semiconductor modules SM are disposed between the base plate 10 and the wiring plate 20 and connected in parallel. For example, when the rated current of the semiconductor module SM is IR, the semiconductor device 1 of rated current N × IR can be configured by arranging N semiconductor modules SM in parallel. Further, by connecting a plurality of semiconductor devices 1 in series, a high-voltage power converter can be configured.

  As shown in FIG. 1, the semiconductor module SM is mounted on the upper surface of the base plate 10 via the bonding member 15. The base plate 10 is, for example, a copper plate, and serves as an electrode and a heat sink. The bonding member 15 is, for example, a solder material, a conductive adhesive, a sintered body of metal particles, an intermetallic compound, or the like.

  The wiring plate 20 is connected to the upper surface of the semiconductor module SM via the bonding member 25. The wiring plate 20 is, for example, a copper plate, and is provided to connect a plurality of semiconductor modules SM in parallel. The bonding member 25 is, for example, a solder material, a conductive adhesive, a sintered body of metal particles, an intermetallic compound, or the like.

  The semiconductor module SM is hermetically sealed on the base plate 10 by the envelope 30, for example. The space between the base plate 10 and the envelope 30 is filled with, for example, a gel-like insulating material or insulating gas.

  FIG. 2 is a schematic cross-sectional view showing a semiconductor module SM1 according to the embodiment. The semiconductor module SM1 includes at least two semiconductor elements 70, a metal plate 50, and a metal plate 60. The semiconductor device 70 is disposed between the metal plate 50 and the metal plate 60.

  The semiconductor element 70 is, for example, a switching element such as an IGBT (Insulated Gate Bipolar Transistor), a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), or an FRD (Fast Recovery Diode) or PIN (P-Intrinsic-N) diode. Etc. Alternatively, the switching element and the diode may be combined and disposed between the metal plate 50 and the metal plate 60.

  The semiconductor module SM1 shown in FIG. 2 includes, for example, semiconductor elements 70a and 70b. Hereinafter, in the present specification, the semiconductor devices 70a and 70b may be individually described or may be comprehensively described as the semiconductor device 70. The same applies to the other components of the semiconductor device 1.

  As shown in FIG. 2, the semiconductor elements 70 a and 70 b are mounted on the upper surface of the metal plate 50 via the bonding members 55 respectively. The metal plate 60 is connected to the upper surface of the semiconductor element 70 via the bonding member 65. For example, the emitter side (or source side, cathode side) of the semiconductor devices 70a and 70b is connected to the metal plate 50, and the metal plate 60 is connected to the collector side (or drain side, anode side).

  The metal plates 50 and 60 are, for example, copper plates and have a thickness of 1 mm or more. Metal plates 50 and 60 preferably have a thickness of 2 mm or more, more preferably 4 mm or more. The metal plates 50 and 60 can, for example, be composed of the same material. Further, in order to suppress the thermal distortion of the semiconductor module SM1, the metal plate 60 may use a material having a linear expansion coefficient different from that of the metal plate 50.

  The bonding members 55 and 65 are, for example, a solder material, a conductive adhesive, a sintered body of metal particles, an intermetallic compound, or the like. The bonding members 55 and 65 contain, for example, any one of silver (Ag), aluminum (Al), gold (Au), copper (Cu) and tin (Sn). Also, bonding members 55 and 65 preferably have a melting point higher than that of bonding members 15 and 25.

  Furthermore, resin members 80 and 85 are provided between the metal plate 50 and the metal plate 60 to seal the semiconductor elements 70a and 70b. The resin member 85 is filled between the semiconductor element 70a and the semiconductor element 70b. Also, the resin member 80 is filled so as to surround the semiconductor elements 70a and 70b. Resin members 80 and 85 may be separate members or may be integrally formed members.

  The resin member 85 is formed to have lower strength than the resin member 80. The resin member 85 has, for example, a composition different from that of the resin member 80. That is, the resin member 85 can be formed using a resin of a type different from that of the resin member 80. Also, the resin member 85 is formed, for example, so that the amount of the dispersed filler is different from that of the resin member 80.

Further, the direction along the upper surface of the metal plate 50, for example, distance _{W 1} between the semiconductor element 70a and the semiconductor element 70b in the X direction is narrower than the distance _{W 2} from the outer surface 80S of the resin member 80 to the semiconductor element 70 Provided as. Thereby, even if the resin members 80 and 85 have the same composition, the strength of the resin member 85 can be made lower than the strength of the resin member 80. For the resin members 80 and 85, for example, a thermosetting resin such as epoxy resin, silicone rubber, or silicone gel can be used.

  Here, the “strength” of the resin member means, for example, a load at the time when the resin members 80 and 85 are divided due to a crack or a crack being generated by a force that extends the resin members 80 and 85 in the Z direction. . The tensile strength or compressive strength of the material constituting each of the resin members 80 and 85 may be used.

  Resin members 80 and 85 are formed, for example, using vacuum forming. That is, the metal plates 50 and 60 on which the semiconductor element 70 is mounted are disposed inside the mold, and the inside is vacuumed, and then filled with a thermosetting resin such as epoxy resin and cured. For example, after the resin member 85 is first filled and cured, a two-step molding method is used in which the resin member 80 is filled around the semiconductor element 70. Alternatively, the resin member 85 may be filled after the resin member 80 is formed with a space left between the semiconductor elements 70. At this time, the resin member 80 is molded such that the lower surface of the metal plate 50 and the upper surface of the metal plate 60 are exposed.

  FIG. 3 is a schematic cross-sectional view showing a short circuit state of the semiconductor module SM1 according to the embodiment. For example, the state after the short circuit failure of the semiconductor element 70 a and the short circuit current flows in the semiconductor device 1 is schematically shown.

If the semiconductor element 70a has a short circuit failure and the other semiconductor elements 70 included in the semiconductor device 1 are normal, most of the on current (short circuit current) of the semiconductor device 1 is concentrated on the semiconductor element 70a. Therefore, the semiconductor element 70a is melted together with the surrounding members by Joule heat to form the conductive melt MC, and forms the conduction path _IP1 . Furthermore, a part of the conductive melt MC is vaporized, and the internal pressure of the space MS formed between the metal plates 50 and 60 is increased. Therefore, cracks CR1 and CR2 are generated in resin members 80 and 85, respectively.

Since the strength of the resin member 85 is lower than the strength of the resin member 80, for example, the crack CR2 of the resin member 85 extends faster than the crack CR1 of the resin member 80 and reaches the semiconductor element 70b. Therefore, the conductive melt MC vaporized by Joule heat reaches the semiconductor element 70b through the crack CR1 and adheres to the side surface thereof. As a result, another conduction path _IP2 is formed on the side surface of the semiconductor element 70b via the conductive melt MC, and the conduction resistance of the semiconductor module SM1 is reduced.

Furthermore, when the crack CR3 is formed inside the semiconductor element 70b, the conduction path _IP3 is formed by the conductive melt adhering to the inside, and the conduction resistance of the semiconductor module SM1 is further reduced. As a result, generation of Joule heat in the semiconductor module SM1 is suppressed, and explosive destruction of the semiconductor device 1 can be avoided.

For example, if the strength of the resin member 85 is equal to or higher than the strength of the resin member 80, the crack CR1 of the resin member 80 also elongates with the rise of the internal pressure, and the conductive melt is a semiconductor through the crack CR1. Scatters out of module SM1. Therefore, the amount of conductive melt MC decreases, the resistance of the conduction path I _P1 is increased, or, conductive path I _P1 is cut off, the conduction resistance of the semiconductor module SM1 is increased. As a result, Joule heat increases and the internal pressure of the space MS further increases. As a result, it may lead to the explosive destruction of the semiconductor device 1.

  In the present embodiment, by making the strength of the resin member 85 in the semiconductor module SM1 lower than the strength of the resin member 80, explosive destruction of the semiconductor device 1 can be avoided. Further, it is preferable to use a material which is combined with the material of the semiconductor element 70 to form the low melting point conductive melt MC for the bonding members 55 and 65.

For example, the bonding members 55 and 65 provided between the semiconductor device 70a and the metal plate 50 and between the metal plate 60 are first melted by Joule heat and combine with the material of the semiconductor device 70a. If the melting point of the resulting conductive melt MC is lower, more conductive melt MC will vaporize. As a result, the amount of the conductive melt MC adhering to the side surface of the semiconductor element 70b can be increased, and the resistance of the conduction path _IP2 can be further reduced. For example, when the material of the semiconductor element 70 is silicon, the bonding members 55 and 65 may be any one of silver (Ag), aluminum (Al), gold (Au), copper (Cu) and tin (Sn). It is preferable to contain two elements.

  FIG. 4 and FIG. 5 are schematic cross-sectional views showing semiconductor modules SM2 and SM3 according to a modification of the embodiment. Each has a structure in which the semiconductor element 70 is disposed between the metal plates 50 and 60. The semiconductor element 70 is molded by resin members 80 and 85. Resin members 80 and 85 may be formed using the same material, or may be formed using different materials.

  In the semiconductor module SM2 shown in FIG. 4, a cavity AG is provided inside the resin member 85. Thereby, the strength of the resin member 85 can be reduced. As a result, when the semiconductor element 70a has a short circuit failure, the conductive melt MC easily adheres to the side surface of the adjacent semiconductor element 70b (see FIG. 3). Thereby, the conduction resistance after the short circuit failure of semiconductor module SM2 can be reduced.

  In the semiconductor module SM3 shown in FIG. 5, another resin member 87 is provided inside the resin member 85. For the resin member 87, a material having lower tensile strength or compressive strength than the material of the resin member 85 is used. Thereby, the strength of the resin members 85 and 87 provided between the adjacent semiconductor elements 70 is lower than the strength of the resin member 80. As a result, the conduction resistance after the short circuit of the semiconductor module SM3 can be reduced.

  As described above, in the semiconductor device 1 according to the embodiment, by providing the semiconductor modules SM1 to SM3 including the resin member 85 with low strength, it is possible to avoid a short circuit failure leading to explosive destruction.

  For example, in a semiconductor device having a configuration in which the plurality of semiconductor elements 70 are directly disposed on the base plate 10 and the wiring plate 20 is in pressure contact with the semiconductor elements 70, the structure of the pressure contact mechanism for reducing conduction resistance at the time of shorting becomes complicated. Is difficult to

  Further, in the pressure contact type semiconductor device, in order to reduce the conduction resistance, it is necessary to widen the contact area of the base plate 10 and the semiconductor element 70 and the contact area of the wiring plate 20 and the semiconductor element 70. Therefore, it is necessary to increase the flatness of the surfaces of the base plate 10 and the wiring plate 20 in contact with the semiconductor element 70, which makes it difficult to reduce the manufacturing cost.

  On the other hand, in the semiconductor modules SM1 to SM3, the semiconductor element 70 is connected to the metal plates 50 and 60 via the bonding members 55 and 65. The semiconductor modules SM <b> 1 to SM <b> 3 are connected to the base plate 10 and the wiring plate 20 via the bonding members 15 and 25. Therefore, the pressure welding mechanism is omitted, and the miniaturization of the semiconductor device 1 is facilitated. Further, by using the bonding members 15, 25, 55 and 65, the flatness required for each surface of the base plate 10, the wiring plate 20 and the metal plates 50 and 60 can be relaxed, and the manufacturing cost can be reduced. .

  In the pressure-contact type semiconductor device, the semiconductor element 70 is inspected in a chip state and then mounted. For this reason, it is difficult to carry out inspection under high voltage and high current. In addition, there is a fear that the semiconductor element 70 may be destroyed by the load at the time of pressure contact. On the other hand, in the semiconductor modules SM1 to SM3, inspection under high voltage and high current is possible. In addition, there is little possibility that the semiconductor modules SM1 to SM3 will fail at the time of mounting. For this reason, in the semiconductor device 1, the manufacturing yield can be improved.

  The semiconductor device 1 and the semiconductor modules SM1 to SM3 described above are examples, and the embodiment is not limited to these. For example, another metal member and a joining member may be interposed between the wiring plate 20 and the metal plate 60. The same applies to the electrical connection between the base plate 10 and the metal plate 50.

  While certain embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

DESCRIPTION OF SYMBOLS 1 ... Semiconductor device, 10 ... Base plate, 15, 25, 55, 65 ... Bonding member, 20 ... Wiring plate, 30 ... Envelope, 50, 60 ... Metal plate, 70 ... Semiconductor element, 80, 85, 87 ... Resin member, 80S ... outer surface, AG ... cavity, CR1, CR2, CR3 ... crack, MC ... conductive melts, MS ... _{space, I P1, I P2, I} P3 ... conduction path, SM, SM1, SM2, SM3 ... Semiconductor module

Claims (7)

A first metal member,
A second metal member disposed in proximity to the first metal member;
At least two semiconductor elements arranged in parallel between the first metal member and the second metal member;
A resin member filled between the first metal member and the second metal member and sealing the semiconductor element;
Equipped with
The semiconductor element is electrically connected to the first metal member via a first bonding member, and is electrically connected to the second metal member via a second bonding member.
The resin member includes a first portion provided between the semiconductor elements and a second portion surrounding the outside of the semiconductor element, and the strength of the first portion is greater than the strength of the second portion. Low semiconductor device.   The semiconductor device according to claim 1, wherein a distance between the semiconductor elements is smaller than a distance from an outer surface of the resin member to the semiconductor elements.   The semiconductor device according to claim 1, wherein the first portion has a composition different from that of the second portion.   The semiconductor device according to claim 1, wherein the first portion has a hollow structure. The resin member further includes a third portion provided inside the first portion,
The semiconductor device according to any one of claims 1 to 4, wherein the strength of the third portion is lower than the strength of the first portion and the strength of the second portion. The semiconductor device contains silicon,
The semiconductor device according to any one of claims 1 to 5, wherein at least one of the first bonding member and the second bonding member contains an element constituting a silicon compound having a melting point lower than that of silicon. .   At least one of the first bonding member and the second bonding member contains at least one element of silver (Ag), aluminum (Al), gold (Au), copper (Cu) and tin (Sn). The semiconductor device according to claim 1, further comprising:

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