JP2007073583A - Manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a semiconductor element in a molding process from being damaged in a manufacturing method of a semiconductor device where a semiconductor element is sandwiched between a pair of metal plates and is sealed with resin. <P>SOLUTION: The manufacturing method is constituted in such a way that the semiconductor element 1 is interposed between a pair of facing metal plates 2, 3, and a member 110 connecting internal surfaces 2a, 3a of the metal plates 2, 3 and the semiconductor element 1 is set in a metal mold 200 into which resin 5 is injected, to mold the member 110. In the molding process, an external surface 2b of the one metal plate 2 and the metal mold 200 are brought into close contact, and there is provided, between an external surface 3b of the other metal plate 3 and the metal mold 200, a gap 230 with such a size that the injected resin 5 is flowable. In this state, the resin 5 is injected and filled in the gap 230, and then the resin 5 covering the external surface 3b of the other metal plate 3 is removed to expose the external surface 3b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device in which a semiconductor element sandwiched between a pair of metal plates is sealed with a resin.

  Conventionally, as this type of semiconductor device, both surfaces of a semiconductor element are sandwiched between a pair of metal bodies functioning as electrodes of the semiconductor element and a heat dissipation member via a joining member such as solder, and these are molded resin. What has been sealed has been proposed (see, for example, Patent Document 1).

Such a semiconductor device generally forms a member in which a semiconductor element is interposed between a pair of metal plates opposed on the inner surface, and the inner surface of each metal plate and the semiconductor element are connected by solder or the like, This member is manufactured by molding the above-mentioned member with a resin by installing the member in a mold and injecting a resin into the mold.
JP 2005-123233 A

  By the way, in this type of semiconductor device, the outer surfaces of both metal plates are exposed from the resin, thereby functioning as a heat radiating surface, thereby improving the heat dissipation of the semiconductor device.

  Here, according to the study of the present inventor, it has been found that the following problems occur when an exposed structure of the outer surfaces of both metal plates is formed by resin molding using a mold, that is, a molding process. 6 and 7 are process diagrams showing a first study example and a second study example conducted by the present inventors, respectively.

  First, as shown in FIG. 6, a member 110 having the semiconductor element 1 sandwiched between a pair of metal plates 2 and 3 is installed in the mold 200. At this time, the outer surfaces 2b of both the metal plates 2 and 3 are arranged. When an exposed structure 3b is to be formed, the outer surfaces 2b and 3b of both metal plates 2 and 3 are brought into close contact with the mold 200 so that the resin is not filled therein.

  However, in the case of the first study example, when the upper mold and the lower mold of the mold 200 are clamped, a compression force (for example, about several tens of MPa) is applied so as to sandwich the member 110, and the metal The component located between the plates 2 and 3, that is, the semiconductor element 1 may be destroyed.

  On the other hand, in the second study example, in order not to apply such compressive force, one metal plate 2 is supported in close contact with the mold 200, and between the other metal plate 3 and the mold 200. Means that a gap 300 having a size (for example, 10 μm or less) that does not allow the resin 5 to enter is provided to perform mold clamping.

  In this case, the resin 5 is injected from the container 210 containing the resin 5 into the mold 200, but the resin 5 does not enter the gap 300, and an unfilled portion 310 that is not filled with the resin 5 exists. Occurs (see FIG. 7C).

  Then, when the resin 5 is cured in the mold 200, the metal plate 3 on which the unfilled portion 310 exists is opposite to the metal plate 3 as shown by the arrow in FIG. The pushing force F from the inner surface side of the metal plate 3 by the resin 5 acts with the metal plate 2 on the side as a fixed portion. The pushing force F also applies a tensile force to the semiconductor element 1 connected to the metal plates 2 and 3, which may cause the semiconductor element 1 to be destroyed.

  The present invention has been made in view of the above problems, and in a semiconductor device manufacturing method in which a semiconductor element sandwiched between a pair of metal plates is sealed with a resin, the destruction of the semiconductor element during the molding step The purpose is to prevent.

  In order to achieve the above-mentioned object, the present inventor, in the molding process, is opposite to the metal plate to which the pushing force by the resin is applied among the pair of metal plates, that is, the one in close contact with the die. It was thought that the outer surface side of the metal plate on the side should be filled with resin.

  By doing so, the metal plate is surrounded not only on the inner surface side but also the outer surface side by the resin, and its surroundings are in a hydrostatic pressure state, so there is no pushing force from the inner surface side to the metal plate, As a result, destruction of the semiconductor element can be prevented.

  However, in this case, after the molding process, the outer surface of the metal plate that is in close contact with the mold is exposed from the resin, but the outer surface of the metal plate on the opposite side is covered with the resin. . However, if the process of removing the resin of the part is performed, the outer surface of both metal plates can be exposed from resin. The present invention has been created based on the above examination results.

  That is, according to the present invention, in the molding step, the outer surface (2b) of one of the pair of metal plates (2, 3) is brought into close contact with the mold (200), and the other metal plate is In a state where a gap (230) having a size that allows the injected resin (5) to flow is provided between the outer surface (3b) and the mold (200), the resin (5) is injected and the resin ( 5) is filled in the gap (230), and then the resin (5) covering the outer surface (3b) of the other metal plate is removed to expose the outer surface (3b).

  According to this, in the mold (200), the resin (5) is filled between the outer surface (3b) of one of the pair of metal plates (2, 3) and the mold (200). The periphery of the metal plate (3) is in a hydrostatic pressure state, and the pushing-up force with respect to the one metal plate (3) is lost, so that the semiconductor element (1) can be prevented from being broken.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1 is a diagram showing a schematic cross-sectional configuration of a semiconductor device 100 according to the first embodiment of the present invention. The semiconductor device 100 is mounted on a vehicle such as an automobile, for example, and is applied as an inverter device used for driving a motor for the vehicle.

  A semiconductor device 100 shown in FIG. 1 includes a semiconductor element 1. The semiconductor element 1 is, for example, a vertical power element such as an IGBT (Insulated Gate Bipolar Transistor).

  Then, both surfaces of the semiconductor element 1 are sandwiched between a pair of metal plates 2 and 3 that function as electrodes and a heat dissipation member of the semiconductor element 1. These metal plates 2 and 3 are made of a metal having good thermal conductivity and electrical conductivity, such as a copper alloy or an aluminum alloy. Here, in FIG. 1, the lower metal body 2 of the pair of metal bodies 2 and 3 is referred to as a first metal body 2, and the upper metal body 3 is referred to as a second metal body 3.

  As shown in FIG. 1, in a semiconductor device 100, a semiconductor element 1 is interposed between a pair of metal plates 2 and 3 facing each other at inner surfaces 2a and 3a, and inner surfaces 2b of the respective metal plates 2 and 3 are disposed. 3a and the semiconductor element 1 are mechanically and electrically further thermally connected by a conductive bonding member 4 such as solder or a conductive adhesive.

  As shown in FIG. 1, in the semiconductor device 100, the pair of metal bodies 2 and 3 sandwiching the semiconductor element 1 are molded and sealed so as to be wrapped by the mold resin 5. The mold resin 5 is made of an epoxy resin or the like, and is formed by mold molding described later.

  Here, as shown in FIG. 1, in each of the pair of metal bodies 2 and 3, the outer surfaces 2 b and 3 b opposite to the inner surfaces 2 a and 3 a facing the semiconductor element 1 are exposed from the mold resin 5. Yes. As a result, the semiconductor device 100 is configured such that heat is radiated through the metal bodies 2 and 3 on both sides of the semiconductor element 1.

  The pair of metal plates 2 and 3 are electrically connected to electrodes (not shown) on each surface of the semiconductor element 1 through the conductive bonding member 4. Although not shown, each of the metal bodies 2 and 3 is provided with an external terminal that protrudes from the end face to the outside of the mold resin 5.

  Although not shown, a control terminal such as a lead frame is provided so as to protrude from the inside of the mold resin 5 to the outside, and the control terminal and the semiconductor element 1 are electrically connected by a bonding wire or the like. . With such terminals, electrical connection between the semiconductor device 100 and the outside is achieved.

  Next, a method for manufacturing the semiconductor device 100 of this embodiment will be described. FIG. 2 is a process diagram showing a molding process of the manufacturing method. In FIG. 2, the conductive bonding member 4 in the semiconductor device 100 is omitted.

  First, the semiconductor element 1 is interposed between a pair of opposing metal plates 2 and 3 to form a member 110 that connects the inner surfaces 2a and 3a of the respective metal plates 2 and 3 and the semiconductor element 1, and this member 110 is formed. Is placed in the mold 200.

  Here, as the mold 200, a general mold for clamping the upper mold and the lower mold can be adopted. Further, a container 210 for storing the molten resin 5 and a passage 220 for injecting the resin 5 from the container 210 into the mold 200 are provided. For example, the resin 5 can be injected from the container 210 into the mold 200 by applying a pressure of about several MPa to the molten resin 5 at about 170 ° C. to 180 ° C.

  Here, as shown in FIG. 2A, of the pair of metal plates 2 and 3, the member 110 is a mold with the first metal plate 2 on the lower side and the second metal plate 3 on the upper side. It is installed in 200. Thereby, the outer surface 2b of the 1st metal plate 2 located in the downward side and the metal mold | die 200 will be in the state closely_contact | adhered by gravity.

  At the same time, a gap 230 is provided between the outer surface 3b of the second metal plate 3 and the mold 200 so that the injected resin 5 can flow. The size of the gap 230 is, for example, 50 μm or more.

  In this state, as shown in FIGS. 2B and 2C, the resin 5 is injected into the mold 200 to mold the member 110 with the resin 5 and fill the gap 230 with the resin 5. To do.

  Then, the resin 5 flows through the gap 230, and the second metal plate 3 is surrounded and sealed not only by the inner surface 3a side but also by the outer surface 3b side. In other words, the periphery of the second metal plate 3 is in a hydrostatic pressure state.

  That is, as shown in FIG. 2 (c), the pressure F2 applied from the inner surface 3a and the pressure F1 applied from the outer surface 3b of the second metal plate 3 are substantially equal to each other. Thus, the pushing force from the inner surface side as described above is lost. As a result, destruction of the semiconductor element 1 can be prevented.

  Thus, after the resin 5 is cured in the mold 200, the member 110 molded with the resin 5 is taken out from the mold 200. FIG. 3 shows a cross-sectional view of the product taken out from the mold 200. As shown in FIG. In this state, the outer surface 2 b of the first metal plate 2 is exposed from the resin 5, but the entire outer surface 3 b of the second metal plate 3 is sealed and covered with the resin 5.

  Therefore, the resin 5 that covers the outer surface 3b of the second metal plate 3 is removed to expose the outer surface 3b. Specifically, as shown in FIG. 4, the removal is performed by cutting using a cutting tool 250. Alternatively, this removal may be polishing using a grindstone or abrasive grains.

  By this removal step, the outer surfaces 2b and 3ba of each of the pair of metal bodies 2 and 3 are exposed from the mold resin 5, and the semiconductor device 100 of the present embodiment shown in FIG. 1 is completed.

  Thus, according to the present embodiment, in the molding process, the metal plate 3 on the side opposite to the side in close contact with the mold 200 has no pushing force from the inner surface 3a side. As a result, the semiconductor in the molding process Destruction of the element 1 can be prevented.

(Second Embodiment)
As shown in FIG. 2 above, when the member 110 is installed in the mold 200, the metal plate 2 on the lower side in the vertical direction is generally adhered to the mold 200 in consideration of the direction of gravity. Is called.

  However, by forming some protrusions in the mold 200 or using a jig or the like, the upper metal plate 3 in FIG. 2 is brought into close contact with the mold 200, and the outer surface 2a of the lower metal plate 2 and the metal mold A gap through which the resin 5 can flow may be provided between the mold 200 and the mold 200.

  In this case, a cross-sectional configuration of the product taken out from the mold 200 is shown in FIG. As shown in FIG. 5, in this case, contrary to FIG. 3, the outer surface 3 b of the second metal plate 3 is exposed from the resin 5, but the outer surface 2 b of the first metal plate 2 is the resin 5. It is covered with. Thereafter, similarly to the above-described embodiment, if a removing process by cutting or polishing is performed, a semiconductor device similar to that shown in FIG.

  That is, as can be seen from the present embodiment and the above embodiment, the outer surface of one of the pair of metal plates 2 and 3 and the mold 200 are brought into close contact with each other, and the outer surface of the other metal plate and the metal plate The molding process may be performed with a gap 230 having a size allowing the injected resin 5 to flow between the mold 200.

(Other embodiments)
In the above embodiment, in the gap 230 having a size that allows the injected resin 5 to flow, the resin 5 flows through the gap 230, and the entire outer surface of the metal plate on the gap 5 side is sealed with the resin 5. I try to stop.

  However, the gap 230 may not be filled with the resin 5 flowing through the entire gap 230 at the time of molding, as long as the pushing-up force due to the hydrostatic pressure state can be substantially eliminated. For example, as shown in FIG. As described above, the flow of the resin 5 may be terminated in a state where the resin 5 is filled up to the middle of the gap 230. Such a gap 230 is also a gap having a size that allows the injected resin 5 to flow.

  In FIG. 2, the first metal body 2 is on the lower side and the second metal body 3 is on the upper side. Conversely, in FIG. 2, the second metal body 3 is on the lower side. As described above, the molding process may be performed with the first metal body 2 on the upper side and the gap 230 provided on the outer surface 2b side. In this case, what is taken out from the mold 200 is as shown in FIG.

  Further, the semiconductor element sandwiched between the pair of metal bodies 2 and 3 of the semiconductor device is not limited to the above as long as the pair of metal bodies 2 and 3 disposed on both surfaces can be used as electrodes. . A plurality of semiconductor elements may be provided.

  Further, a metal block member, a so-called heat sink block, may be interposed between the semiconductor element 1 and the inner surfaces 2a and 3a of the metal plates 2 and 3 via a conductive bonding member.

1 is a schematic cross-sectional view of a semiconductor device according to a first embodiment of the present invention. It is process drawing which shows the mold process in the manufacturing method of the semiconductor device of 1st Embodiment. It is sectional drawing of the member shape | molded by the molding process shown by FIG. It is a figure which shows the removal method by cutting using a blade tool. It is sectional drawing of the member shape | molded by the molding process which concerns on 2nd Embodiment of this invention. It is a figure which shows the 1st example of examination which this inventor performed. It is a figure which shows the 2nd example of examination which this inventor performed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor element, 2 ... 1st metal plate, 2a ... Inner surface of 1st metal plate,
2b ... the outer surface of the first metal plate, 3 ... the second metal plate, 3a ... the inner surface of the second metal plate,
3b: outer surface of the second metal plate, 5 ... mold resin, 110 ... member, 200 ... mold.

Claims (3)

A semiconductor element (1) is interposed between a pair of opposing metal plates (2, 3), and the inner surfaces (2a, 3a) of the respective metal plates (2, 3) are connected to the semiconductor element (1). The member (110) is formed, the member (110) is placed in the mold (200), and the resin (5) is injected into the mold (200), whereby the resin (5) In the method of manufacturing a semiconductor device in which the member (110) is molded,
In the molding step, the outer surface (2b) of one of the pair of metal plates (2, 3) is brought into close contact with the mold (200) and the outer surface (3b) of the other metal plate. ) And the mold (200), the resin (5) is injected in a state where a gap (230) having a size allowing the injected resin (5) to flow is provided. (5) is filled in the gap (230),
Thereafter, the member (110) molded with the resin (5) is taken out from the mold (200), and the resin (5) covering the outer surface (3b) of the other metal plate is removed, A method of manufacturing a semiconductor device, wherein the outer surface (3b) is exposed. In the molding step, the outer surface (2b) of one of the pair of metal plates (2, 3) is positioned on the lower side to be in close contact with the mold (200) and the other metal The outer surface (3b) of the plate is positioned on the upper side and the gap (230) is provided between the mold (200) and the resin (5) flows through the gap (230). The method of manufacturing a semiconductor device according to claim 1, wherein: The resin (5) flows through the gap (230) and the entire outer surface (3b) of the other metal plate is sealed with the resin (5). 3. A method for manufacturing a semiconductor device according to 2.

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