JP2012244040A - Semiconductor device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device and the like capable of efficiently protecting a semiconductor chip from sputters at the time of laser welding by a relatively small quantity of resin and with a good workability, and having an excellent thermal diffusion property.SOLUTION: A semiconductor device 1, 2, 3 has: a heat spreader 20, 200 having recessed parts 22A and 22B; semiconductor chips 10A and 10B fixed in the recessed parts of the heat spreader; a connection conductor 12 fixed to the semiconductor chips 10A and 10B; an insulation resin part 70 covering the semiconductor chips 10A and 10B in the recessed parts 22A and 22B of the heat spreader while exposing a weld part 121 of the connection conductor; and an external terminal 80 bonded to the weld part of the connection conductor by laser welding.

Description

  The present invention relates to a semiconductor device in which a connection conductor and an external terminal are joined by laser welding and a method for manufacturing the same.

  Conventionally, this type of semiconductor device is known (see, for example, Patent Documents 1 and 2). In the semiconductor devices described in Patent Documents 1 and 2, the semiconductor chip is covered with a resin in order to prevent damage to the semiconductor chip due to sputtering generated by laser welding.

International Publication No. 2009/081723 Pamphlet JP 2010-141163 A

  However, in the semiconductor devices described in Patent Document 1 and Patent Document 2, the semiconductor chip is joined to the insulating substrate with the ceramic sandwiched from above and below by soldering. In the configuration using such an insulating substrate, there is a disadvantage that the thermal diffusibility is inferior to the configuration using the heat spreader.

  By the way, it is advantageous if the resin for covering the semiconductor chip can efficiently protect the semiconductor chip with a small amount. In general, the resin used to cover the semiconductor chip has fluidity, so it can spread to unnecessary areas. In such a case, not only the workability is poor, but the amount of resin used is unnecessarily high and the cost is low. The above problems can also arise. Further, when the resin is filled over the entire surface of the substrate, an intermediate terminal (for example, the connection conductor 14 in the semiconductor device described in Patent Document 1 is used for electrical connection between the electrode of the semiconductor chip and the external terminal. ) And the like may be required, and there is a problem that the number of parts and the number of work steps increase.

  Accordingly, the present invention provides a semiconductor device excellent in thermal diffusibility and a method for manufacturing the same, which can efficiently protect a semiconductor chip from sputtering during laser welding with a relatively small amount of resin with good workability. Objective.

In order to achieve the above object, according to one aspect of the present invention, a heat spreader having a recess,
A semiconductor chip fixed in the recess of the heat spreader;
A connection conductor fixed to the semiconductor chip;
An insulating resin portion that covers the semiconductor chip in the recess of the heat spreader while exposing the welded portion of the connection conductor;
An external terminal joined by laser welding to the welded portion of the connection conductor is provided. A semiconductor device is provided.

According to another aspect of the present invention, a step of fixing a semiconductor chip in the recess of the heat spreader including the recess,
Fixing the connection conductor to the semiconductor chip;
In the aspect of covering the semiconductor chip while exposing the planned welding portion of the connection conductor, filling the resin into the recess of the heat spreader;
There is provided a method of manufacturing a semiconductor device, including a step of joining an external terminal to the exposed welding portion of the connection conductor by laser welding.

  According to the present invention, it is possible to obtain a semiconductor device excellent in thermal diffusibility and a method for manufacturing the same, which can efficiently protect a semiconductor chip from sputtering during laser welding with a relatively small amount of resin with good workability. .

It is a figure which shows the principal part of the semiconductor device 1 by one Example (Example 1) of this invention by a top view. FIG. 2 is a cross-sectional view taken along line AA of the semiconductor device 1 shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line BB of the semiconductor device 1 shown in FIG. 1. It is a single figure of the heat spreader 20, (A) shows a top view, (B) shows sectional drawing along line AA. It is a figure which shows a main example of the generation | occurrence | production mechanism of the pressure | voltage resistant defect of IGBT resulting from the sputter | spatter at the time of laser welding. It is a figure which shows the principal part of the semiconductor device by a comparative example by a top view. It is sectional drawing along line AA of the semiconductor device by the comparative example shown in FIG. FIG. 7 is a cross-sectional view taken along line BB of the semiconductor device according to the comparative example shown in FIG. 6. FIG. 3 is a diagram sequentially illustrating a main part (part 1) of an example of a flow of a manufacturing method of the semiconductor device 1 illustrated in FIG. 1. FIG. 3 is a diagram sequentially illustrating a main part (part 2) of the flow of an example of a method for manufacturing the semiconductor device 1 illustrated in FIG. 1. It is a perspective view which shows the semiconductor device 2 by another Example (Example 2). It is sectional drawing of the semiconductor device 3 by another Example (Example 3).

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a top view of a main part of a semiconductor device 1 according to an embodiment (embodiment 1) of the present invention. FIG. 2 is a cross-sectional view taken along line AA of the semiconductor device 1 shown in FIG. FIG. 3 is a cross-sectional view taken along line BB of the semiconductor device 1 shown in FIG. FIG. 4 is a single product diagram of the heat spreader 20, FIG. 4 (A) shows a top view, and FIG. 4 (B) shows a cross-sectional view along line AA. In FIG. 1, the first external terminal 80 is shown in a perspective view for convenience of understanding the configuration below the first external terminal 80. Although the vertical direction of the semiconductor device 1 differs depending on the mounting state of the semiconductor device 1, hereinafter, for convenience, the side where the semiconductor chip 10 exists is defined as the upper side with respect to the heat spreader 20 of the semiconductor device 1. . The semiconductor device 1 may constitute an inverter for driving a motor used in, for example, a hybrid vehicle or an electric vehicle.

  As shown in FIGS. 1 and 2, the semiconductor device 1 includes a semiconductor chip 10, a connection conductor 12, a heat spreader 20, an insulating resin portion 70, a first external terminal 80, and a second external terminal 82. .

  The semiconductor chip 10 includes a power semiconductor element, and in this example includes an IGBT (Insulated Gate Bipolar Transistor). The type and number of power semiconductor elements included in the semiconductor chip 10 are arbitrary. The semiconductor chip 10 may include another switching element such as a MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) instead of the IGBT. The semiconductor chip 10 is bonded onto the heat spreader 20 with solder 50. In the illustrated example, the semiconductor chip 10 includes a semiconductor chip 10A made of IGBT and a semiconductor chip 10B made of FWD (Free Wheeling Diode). In this case, the semiconductor chip 10A includes an emitter electrode on the upper surface and a collector electrode on the lower surface. Further, the semiconductor chip 10B includes an anode electrode on the upper surface and a cathode electrode on the lower surface.

  The heat spreader 20 is a member that absorbs and diffuses heat generated in the semiconductor chip 10. The heat spreader 20 may be formed of a metal having excellent thermal diffusibility such as copper or aluminum. As copper, oxygen-free copper (C1020) having the highest conductivity among copper materials is suitable.

  As shown in FIG. 4, the heat spreader 20 has recesses 22A and 22B corresponding to the installation areas of the semiconductor chips 10A and 10B. Recesses 22A and 22B are formed on the upper surface of heat spreader 20 (the surface on which semiconductor chips 10A and 10B are installed). The recesses 22A and 22B may be formed by pressing, for example. The recesses 22A and 22B have outer shapes larger than the outer shapes of the semiconductor chips 10A and 10B, respectively, as viewed from above so that the semiconductor chips 10A and 10B can be included therein. The depth D of the recesses 22A and 22B is the same as the total thickness obtained by adding the thickness (height) of the semiconductor chips 10A and 10B and the thickness of the solder 50 below the semiconductor chips 10A and 10B, as will be described below. Or, it is set to be larger than that. The depth D of the recess 22A and the depth D of 22B of the recess 22A may be the same, but are not necessarily the same. For example, the depth D of the recesses 22A and 22B may be set according to the thickness of the corresponding semiconductor chips 10A and 10B. In the illustrated example, the recesses 22A and 22B are separately formed in a manner that is not continuous with each other, but may be formed in a manner that is continuous with each other. That is, the recesses 22A and 22B may be formed as one recess without the partition 22c (see FIG. 4) between the recesses 22A and 22B. Each of the recesses 22A and 22B typically has a certain depth, but the depth may vary. For example, the steps for positioning the semiconductor chips 10A and 10B in the recesses 22A and 22B may be formed on the surfaces in the recesses 22A and 22B (the bottom surfaces of the recesses 22A and 22B). In addition, the surfaces in the recesses 22A and 22B may be smooth surfaces or fine irregularities may be formed. The minute unevenness may be formed in order to manage the thickness of the solder 50 that realizes the bonding between the semiconductor chips 10A and 10B and the heat spreader 20. In the following, the upper surface of the heat spreader 20 refers to the upper surface of a region where the recesses 22A and 22B are not formed in the heat spreader 20, unless otherwise specified.

  The semiconductor chips 10A and 10B are fixed in the recesses 22A and 22B of the heat spreader 20, as shown in FIGS. The semiconductor chips 10A and 10B are preferably fixed in the recesses 22A and 22B in such a manner that they do not protrude above the basic surface of the heat spreader 20 (the surface of the region where the recesses 22A and 22B are not formed). As described above, the semiconductor chips 10A and 10B are fixed (bonded) to the heat spreader 20 with the solder 50 in the respective recesses 22A and 22B. The semiconductor chips 10A and 10B may be fixed in the recesses 22A and 22B in such a manner that they are separated from the peripheral walls 221 and the partition walls 22c in the recesses 22A and 22B in the lateral direction (in a direction perpendicular to the vertical direction).

  The connection conductor 12 is fixed (bonded) to the electrodes of the semiconductor chips 10A and 10B with solder 50. In the illustrated example, the connection conductor 12 is joined to the IGBT emitter electrode and the FWD anode electrode by solder 50. As shown in FIG. 2, the connection conductor 12 has a convex shape upward, and includes an upper part 121 spaced upward from the upper surface of the heat spreader 20 and two heights extending near the upper surface of the heat spreader 20. The connection part 122 is comprised from the upper part 121 and the leg part 123 of the up-down direction which connects the two connection parts 122. FIG. The two connection parts 122 are joined to the emitter electrode of the IGBT and the anode electrode of the FWD, respectively. The upper part 121 of the connection conductor 12 defines a weld for joining to the first external terminal 80 as will be described later.

  As shown in FIGS. 1 and 2, the insulating resin portion 70 is formed in the recesses 22 </ b> A and 22 </ b> B of the heat spreader 20. Specifically, the recesses 22A and 22B of the heat spreader 20 are filled with resin in a state in which the semiconductor chips 10A and 10B to which the connection conductor 12 is bonded as described above are included. The resin is preferably filled only in the recesses 22A and 22B so as not to spread outward from the outer shape of the recesses 22A and 22B in a top view. That is, the peripheral walls 221 (see FIG. 4) in the recesses 22A and 22B function to block the resin filled in the recesses 22A and 22B from spreading outside the outer shape of the recesses 22A and 22B in a top view. . Thus, the insulating resin portion 70 is formed in the recesses 22A and 22B by the resin filled in the recesses 22A and 22B. In addition, resin which comprises the insulating resin part 70 may be arbitrary resin materials, for example, an epoxy resin may be used.

  The maximum thickness of the insulating resin portion 70 may be a thickness corresponding to the depth of the recesses 22A and 22B as shown in FIG. The insulating resin portion 70 only needs to cover the semiconductor chips 10A and 10B in such a manner that at least the semiconductor chips 10A and 10B can be protected from sputtering during laser welding described later. That is, the insulating resin portion 70 is provided so as to cover the entire surface including the upper surfaces of the semiconductor chips 10A and 10B (the entire surface excluding the lower surface). In the illustrated example, as described above, the depth D of the recesses 22A and 22B is larger than the total thickness obtained by adding the thickness of the semiconductor chips 10A and 10B and the thickness of the solder 50 below the semiconductor chips 10A and 10B. It is set to be. The insulating resin portion 70 has a thickness corresponding to the depth of the recesses 22A and 22B, thereby covering the entire surface including the upper surfaces of the semiconductor chips 10A and 10B. In the example shown in the figure, the insulating resin portion 70 is formed in the vertical direction with the upper surface of the solder 50 (that is, the lower surface of the connection portion 122 of the connection conductor 12) that realizes the bonding between the semiconductor chips 10A and 10B and the connection conductor 12. Extends to approximately the same height. The upper part 121 of the connection conductor 12 is not covered with the insulating resin part 70 and is exposed above the insulating resin part 70. Note that the maximum thickness of the insulating resin portion 70 may be slightly larger than the depths of the recesses 22A and 22B using the surface tension during filling.

  Note that the upper surface of the heat spreader 20 may be further coated with a resin other than the resin constituting the insulating resin portion 70. For example, a gel material such as silicon gel may be applied so as to seal the upper surface of the heat spreader 20. However, in this case, the gel material is provided after the joining of the second external terminal 82 described later to the heat spreader 20 by laser welding is completed.

  As shown in FIGS. 1 and 2, the first external terminal 80 is joined to the upper portion 121 of the connection conductor 12 by laser welding. The first external terminal 80 extends away from the upper surface of the heat spreader 20 and above the heat spreader 20. The first external terminal 80 is provided at a height corresponding to the upper portion 121 of the connection conductor 12. As shown in FIG. 1, the first external terminal 80 extends so as to overlap the upper portion 121 of the connection conductor 12 in a top view. The width of the first external terminal 80 (the length in the direction perpendicular to the longitudinal direction) may be arbitrary. In the illustrated example, the width of the first external terminal 80 is substantially the same as the width of the upper portion 121 of the connection conductor 12 as shown in FIG. 1, but is set larger than the width of the upper portion 121 of the connection conductor 12. Also good. In the illustrated example, the first external terminal 80 has a planar shape extending in the same plane above the heat spreader 20, but may have a step difference in the vertical direction.

  The first external terminal 80 and the upper part 121 of the connection conductor 12 may be joined by welding at one welding point 80a, 12a as shown in FIGS. May be joined together. The welding points 80a and 12a between the first external terminal 80 and the connection conductor 12 are preferably set at positions offset upward from the upper surface of the heat spreader 20 and further upward from the upper surface of the semiconductor chips 10A and 10B. The In the illustrated example, the welding point 12 a on the connection conductor 12 side is set to an upper portion 121 that is spaced upward from the upper surface of the heat spreader 20.

  As shown in FIGS. 1 and 3, the second external terminal 82 is joined to the upper surface of the heat spreader 20 by laser welding. The heat spreader 20 is connected to the collector electrode of the IGBT as the semiconductor chip 10A (and the cathode electrode of the FWD as the semiconductor chip 10B) as described above. To do. As shown in FIG. 3, the second external terminal 82 has a portion that protrudes downward, as shown in FIG. 3, and this portion extends to a height that is spaced upward from the upper surface of the heat spreader 20. And a lower part 821 in contact with the upper surface of the heat spreader 20 and an upper and lower leg part 823 that connects the upper part 822 and the lower part 821. The lower part 821 of the second external terminal 82 defines a weld for joining to the upper surface of the heat spreader 20. As shown in FIG. 1, the lower portion 821 of the second external terminal 82 faces the surface of the heat spreader 20 where the recesses 22 </ b> A and 22 </ b> B are not present, as shown in FIG. 1. The upper part 822 of the second external terminal 82 may extend to the same height as the first external terminal 80. The second external terminal 82 may be incorporated in the same bus bar module (see FIG. 11) together with the first external terminal 80. Further, as shown in FIG. 1, the second external terminal 82 extends above a region where the recesses 22 </ b> A and 22 </ b> B do not exist in the heat spreader 20 in a parallel relationship with the first external terminal 80 as viewed from above. May be.

  The lower part 821 of the second external terminal 82 and the upper surface of the heat spreader 20 may be joined by welding at one welding point 82a, 20a as shown in FIGS. 1 and 3, or two or more welding points. May be joined together. The second external terminal 82 is preferably directly joined to the upper surface of the heat spreader 20. As a result, the collector electrode of the IGBT can be directly taken out without requiring an intermediate terminal (for example, the intermediate terminal 14 shown in FIG. 8).

  FIG. 5 is a diagram illustrating a main example of the generation mechanism of the breakdown voltage failure of the IGBT caused by sputtering during laser welding, and is a diagram illustrating a cross-sectional view of the IGBT corresponding to the semiconductor chip 10A. The generation mechanism of this breakdown voltage failure is the same in the case of FWD.

  During laser welding, soot (carbon) may be generated as spatter. Such wrinkles occur, for example, when the surrounding resin is burned during laser welding. As shown in FIG. 5, when such a flaw adheres to the edge portion of the semiconductor chip (IGBT), it is considered that a breakdown voltage failure occurs due to a short circuit between the collector and the emitter.

  Here, according to the present embodiment, as described above, the semiconductor chips 10A and 10B have their upper surfaces and side surfaces (that is, upper surfaces and side surfaces constituting the edge portions) protected by the insulating resin portion 70 in the recesses 22A and 22B. . Therefore, even when wrinkles occur during laser welding of the first external terminal 80 and the second external terminal 82 as shown in FIG. 5, the wrinkles adhere to the edge portions of the semiconductor chips 10A and 10B by the insulating resin portion 70. Can be prevented. As a result, it is possible to prevent a breakdown voltage failure from occurring in the semiconductor chips 10A and 10B due to sputtering during laser welding. Further, since the semiconductor chips 10A and 10B can be protected by the insulating resin portion 70, a special jig or the like for protecting the semiconductor chips 10A and 10B during laser welding can be eliminated.

  FIG. 6 is a diagram showing a main part of a semiconductor device according to a comparative example in a top view. FIG. 7 is a sectional view taken along line AA of the semiconductor device according to the comparative example shown in FIG. FIG. 8 is a cross-sectional view taken along line BB of the semiconductor device according to the comparative example shown in FIG. 6 to 8, the same reference numerals are assigned to the corresponding components in the semiconductor device 1 according to the present embodiment shown in FIGS. 1 to 4.

  In the semiconductor device according to the comparative example, the recesses 22A and 22B according to the present embodiment are not formed in the heat spreader 20 ′. Therefore, the semiconductor chips 10A and 10B are provided on the upper surface of the heat spreader 20 ′, and the heat spreader 20 ′ An insulating resin portion 70 ′ is provided with a constant thickness over the entire top surface. In other words, the insulating resin portion 70 ′ is formed with a predetermined thickness above the upper surface of the heat spreader 20 ′ so as to cover the upper surfaces of the semiconductor chips 10 </ b> A and 10 </ b> B located higher than the upper surface of the heat spreader 20 ′. Further, since the insulating resin portion 70 ′ is formed over the entire upper surface of the heat spreader 20 ′, the intermediate terminal 14 for taking out the collector electrode is joined to the upper surface of the heat spreader 20 ′ by the solder 50. The semiconductor chips 10A and 10B are bonded to the upper surface of the heat spreader 20 ′, the connection conductor 12 is bonded to the semiconductor chips 10A and 10B, and the intermediate terminal 14 is bonded by the solder 50, and then the insulating resin portion 70 ′ is formed. The

  Here, in this comparative example, since the entire semiconductor chips 10A and 10B are covered with the insulating resin portion 70 ′, laser welding between the first and second external terminals 80 and 82 ′ and the connection conductor 12 and the intermediate terminal 14 is performed. The semiconductor chips 10A and 10B can be protected from spattering. However, since the insulating resin portion 70 ′ covers the entire upper surface of the heat spreader 20 ′, the amount of resin required to form the insulating resin portion 70 ′ is relatively large. Further, since the insulating resin portion 70 ′ covers the entire upper surface of the heat spreader 20 ′, an intermediate terminal 14 for taking out the collector terminal to the second external terminal 82 ′ is required as shown in FIG. 8. That is, since the second external terminal 82 ′ cannot be directly bonded to the upper surface of the heat spreader 20 ′, it is necessary to set the intermediate terminal 14 exposed upward from the insulating resin portion 70 ′. Therefore, in the configuration of the comparative example, not only the cost increases due to the relatively large amount of resin used but also the intermediate terminal 14 is required, so that the number of parts and the number of work steps increase.

  On the other hand, according to the present embodiment, as described above, the semiconductor chips 10A and 10B are accommodated in the recesses 22A and 22B of the heat spreader 20, and the resin is filled only in the recesses 22A and 22B of the heat spreader 20. An insulating resin portion 70 that protects the chips 10A and 10B is formed. Therefore, compared to the comparative example in which the insulating resin portion 70 ′ covers the entire upper surface of the heat spreader 20 ′, the amount of resin necessary for forming the insulating resin portion 70 that protects the semiconductor chips 10A and 10B can be reduced. it can. Further, since there is a region where the insulating resin portion 70 is not formed on the upper surface of the heat spreader 20, it is possible to directly bond the second external terminal 82 to the upper surface of the heat spreader 20 (region where the insulating resin portion 70 is not formed) The intermediate terminal 14 as required in the above comparative example can be eliminated. In addition, according to the present embodiment, since the insulating resin portion 70 is formed by filling the recesses 22A and 22B of the heat spreader 20 with the resin, the resin flow is restricted in the recesses 22A and 22B due to the action of surface tension and the like. Undesirable flow (spreading) of the resin to the upper surface of the heat spreader 20 (the upper surface of the region where the recesses 22A and 22B are not formed in the heat spreader 20) can be prevented. As described above, according to the present embodiment, the electrical connection between the semiconductor chips 10A and 10B and the second external terminal 82 can be efficiently realized, and the semiconductor chip is formed with a relatively small amount of resin with good workability. 10A and 10B can be protected efficiently.

  9 to 10 are diagrams showing an example of a main part of an example of the flow of the manufacturing method of the semiconductor device 1 shown in FIG. 9A to 9C correspond to the cross section along the line AA in FIG. 1, and FIGS. 10A to 10B correspond to the cross section along the line AA in FIG. 10C corresponds to a cross section taken along line BB in FIG.

  First, as shown in FIG. 9A, a heat spreader 20 having recesses 22A and 22B is prepared. Here, a single heat spreader 20 is prepared for convenience of explanation for easy understanding. However, the heat spreader 20 may be provided with a hoop material for forming a plurality of heat spreaders 20, and the hoop material may be cut and divided into heat spreaders 20 at the final stage.

  Next, as shown in FIG. 9B, the semiconductor chips 10 </ b> A and 10 </ b> B are joined by solder 50 in the recesses 22 </ b> A and 22 </ b> B of the heat spreader 20. At this time, in the recesses 22 </ b> A and 22 </ b> B, spaces other than the portions occupied by the semiconductor chips 10 </ b> A and 10 </ b> B and the solder 50 are spaces.

  Next, as illustrated in FIG. 9C, the connection conductor 12 is joined to the semiconductor chips 10 </ b> A and 10 </ b> B with solder 50.

  Next, as shown in FIG. 10A, the recesses 22A and 22B are filled with resin, and an insulating resin portion 70 that covers the semiconductor chips 10A and 10B is formed. At this time, the portion to be welded of the connection conductor 12, that is, the upper portion 121 of the connection conductor 12 is exposed from the insulating resin portion 70.

Next, as shown in FIG. 10B, the first external terminal 80 is joined to the upper portion 121 of the connection conductor 12 exposed from the insulating resin portion 70 by laser welding. Laser welding may be performed by irradiating the first external terminal 80 with laser light in a substantially perpendicular direction from above with the first external terminal 80 pressed downward against the upper portion 121 of the connection conductor 12. Good. As a laser used for such laser welding, for example, an arbitrary laser such as a YAG laser, a CO ₂ laser, or a semiconductor laser may be used.

  Next, as shown in FIG. 10C, the second external terminal 82 is joined to the upper surface of the heat spreader 20 (parts other than the recesses 22A and 22B) by laser welding. Similarly, the laser welding is performed by irradiating the second external terminal 82 with laser light in a substantially perpendicular direction from above with the second external terminal 82 pressed downward against the upper surface of the heat spreader 20. Also good. The joining of the second external terminals 82 may be performed before the joining of the first external terminals 80 or simultaneously with the joining of the first external terminals 80. In short, the joining of the first external terminal 80 and the second external terminal 82 may be performed at any appropriate timing as long as the insulating resin portion 70 is formed. For example, laser welding of the first external terminal 80 and the second external terminal 82 may be performed after the resin forming the insulating resin portion 70 is completely cured, or the resin forming the insulating resin portion 70 is cured. It may be executed before In addition, after joining the 1st external terminal 80 and the 2nd external terminal 82, a gel material like a silicon gel may be provided so that the upper surface of the heat spreader 20 may be sealed.

  FIG. 11 is a perspective view showing a semiconductor device 2 according to another embodiment (embodiment 2), and shows a state before the bus bar module 60 is assembled. In the second embodiment, components that may be substantially the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the second embodiment, six heat spreaders 20 are mounted as one module. The configuration of each heat spreader 20 may be the same as that of the semiconductor device 1 according to the first embodiment described above. Each of the semiconductor chips 10A and 10B on the six heat spreaders 20 may constitute the U-phase, V-phase, and W-phase upper arms and the lower arms of the motor drive inverter. In this manner, any number of heat spreaders 20 may be included in one module.

  The bus bar module 60 may include six sets of first external terminals 80 and second external terminals 82 corresponding to the six heat spreaders 20. The 1st external terminal 80 and the 2nd external terminal 82 may be modularized by the support body 84 formed with resin. The bus bar module 60 may be formed by resin insert molding, for example. In the second embodiment, the laser bar welding is sequentially or simultaneously performed on each of the first external terminals 80 and the second external terminals 82 in a state where the bus bar module 60 is positioned with respect to each heat spreader 20 and pressed downward. May be executed. Moreover, after joining each 1st external terminal 80 and 2nd external terminal 82 by laser welding, a gel material may be provided so that the upper surface of each heat spreader 20 may be sealed.

  In addition, the heat spreader 20 may be joined to the heat sink 40 via the insulating layer 30, as shown in FIG. The insulating layer 30 may be composed of a resin adhesive or a resin sheet. The insulating layer 30 may be formed of a resin using alumina as a filler, for example. The insulating layer 30 is provided between the heat spreader 20 and the heat sink 40 and is bonded to the heat spreader 20 and the heat sink 40. The insulating layer 30 ensures high thermal conductivity from the heat spreader 20 to the heat sink 40 while ensuring electrical insulation between the heat spreader 20 and the heat sink 40. The heat sink 40 is formed of a material having good thermal conductivity, and may be formed of a metal such as aluminum, for example. The upper surface of the heat sink 40 is bonded to the heat spreader 20. The heat sink 40 includes fins 42 on the lower surface side. The number and arrangement of the fins 42 are arbitrary. The fins 42 may be straight fins as illustrated, or may be realized by staggered arrangement of pin fins. In the mounted state of the semiconductor device 2, the fins 42 are in contact with a cooling medium such as cooling water or cooling oil. In this way, the heat from the semiconductor chip 10 generated when the semiconductor device 2 is driven is transmitted to the cooling medium from the fins 42 of the heat sink 40 via the heat spreader 20 and the insulating layer 30, and cooling of the semiconductor device 2 is realized. Is done.

  12 is a cross-sectional view of the semiconductor device 3 according to another embodiment (embodiment 3), and corresponds to a cross-sectional view along the line BB of the semiconductor device 1 shown in FIG. The third embodiment is different from the configuration of the semiconductor device 1 according to the first embodiment described above in that the second external terminal 82 is integrally formed with the heat spreader 200 as the second external terminal portion 202. In the third embodiment, components that may be substantially the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the third embodiment, the heat spreader 200 integrally includes a main body portion 201 and a second external terminal portion 202. The heat spreader 200 may be formed of, for example, a modified material lead frame. In this case, since the main body part 201 and the second external terminal part 202 are initially connected, joining (laser welding) between the main body part 201 and the second external terminal part 202 is not necessary. The end of the second external terminal 202 (the end opposite to the main body 201) may be connected to a substrate (not shown) by soldering or the like. The other configuration of the main body 201 may be the same as the configuration of the heat spreader 20 of the semiconductor device 1 according to the first embodiment described above (particularly, the configuration described with reference to the cross-sectional view of FIG. 2).

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the first embodiment described above, the semiconductor device 1 may include another configuration (for example, a part of a DC / DC boost converter element for driving the traction motor), and the semiconductor device 1 may be a semiconductor device. Other elements (capacitor, reactor, etc.) may be included together with the chips 10A, 10B. Moreover, although the semiconductor device 1 was applied to the inverter for vehicles, the semiconductor device 1 may be used for the inverter used for other purposes (railway, air conditioner, elevator, refrigerator, etc.). . Further, the semiconductor device 1 may be used in a device other than an inverter, for example, an MPU (Microprocessor Unit) for a computer or a high-frequency power module used in a power amplification circuit of a transmission unit of a wireless communication device. The same applies to the second and third embodiments.

  In the first embodiment, since the heat spreader 20 is equipotential with the collector electrode of the IGBT, the second external terminal 82 for taking out the collector electrode is joined to the heat spreader 20 by laser welding. When a semiconductor chip 10A made of a MOSFET is used instead of the IGBT, the heat spreader 20 is equipotential with the drain electrode of the MOSFET, so that a similar second external terminal 82 for taking out the drain electrode is placed on the heat spreader 20. What is necessary is just to join by laser welding.

  In the first embodiment described above, the upper surface of the heat spreader 20 and the like can be sealed with a resin (for example, silicon gel) that is less expensive than the resin that forms the insulating resin portion 70, but such sealing may be omitted. Good. Alternatively, the upper surface of the heat spreader 20 may be sealed with the same resin as that forming the insulating resin portion 70. The same applies to the second and third embodiments.

  In the first embodiment described above, the insulating resin portion 70 covers the entire top surface of the semiconductor chips 10A and 10B (the entire surface excluding the region where the connection portion 122 of the connection conductor 12 is joined). It may be configured to cover only the edge portions of 10A and 10B, that is, only the outer peripheral portion and the side surface of the upper surface of the semiconductor chips 10A and 10B. Specifically, the guard ring (ring-shaped insulating portion for insulating between the emitter electrode and the collector electrode) shown in FIG. 5 may be covered, or the guard ring and its periphery may be covered. . However, it is desirable that the insulating resin portion 70 covers the entire upper surface of the semiconductor chips 10A and 10B in order to prevent physical damage due to the direct sputtering collision with the upper surfaces of the semiconductor chips 10A and 10B. The same applies to the second and third embodiments.

1, 2 and 3 Semiconductor device 10 (10A, 10B) Semiconductor chip 12 Connection terminal 12a Welding point 20,200 Heat spreader 20a Welding point 22A, 22B Recessed part 30 Insulating layer 40 Heat sink 42 Fin 50 Solder 60 Bus bar module 70 Insulating resin part 80 DESCRIPTION OF SYMBOLS 1 External terminal 80a Welding point 82 2nd external terminal 82a Welding point 84 Support body 121 Upper part 122 Connection part 201 Main body part 202 2nd external terminal part 221 Peripheral wall 821 Lower part 822 Upper part 823 Leg part

Claims (4)

A heat spreader having a recess;
A semiconductor chip fixed in the recess of the heat spreader;
A connection conductor fixed to the semiconductor chip;
An insulating resin portion that covers the semiconductor chip in the recess of the heat spreader while exposing the welded portion of the connection conductor;
An external terminal joined by laser welding to a welded portion of the connection conductor.   The semiconductor device according to claim 1, further comprising a second external terminal directly joined to the heat spreader by laser welding.   The semiconductor device according to claim 1, wherein a depth of the concave portion of the heat spreader is larger than a height of a semiconductor chip fixed in the concave portion. Fixing a semiconductor chip in the recess of the heat spreader including the recess;
Fixing the connection conductor to the semiconductor chip;
In the aspect of covering the semiconductor chip while exposing the planned welding portion of the connection conductor, filling the resin into the recess of the heat spreader;
And a step of joining an external terminal to the exposed welding portion of the connection conductor by laser welding.

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