Semiconductor equipment

Abstract

To provide a highly reliable semiconductor device.SOLUTION: The semiconductor device according to an embodiment includes: a pellet; a first conductor and a second conductor for holding the pellet in a first direction; a first joint material for joining the pellet and the first conductor to each other; and a second joint material for joining the pellet and the second conductor to each other. A first surface of the first conductor, which faces the pellet, has a plurality of protrusions overlapping with the pellet and a trench surrounding the pellet when the first surface is seen from the first direction. The design value of the height of the protrusions is a first value. The volume of the trench is determined based on the volume of the part between the pellet and the first conductor in a case where a first height between the pellet and the first conductor is a second value, which is larger than the first value.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Embodiments of the present invention relate to a semiconductor device.

Background Art

[0002] A semiconductor device having a structure in which upper and lower surfaces of a pellet are connected to electric conductors via a bonding material is known.

Prior Art Literature

Patent Literature

[0003]

Patent Literature 1

Patent Literature 2

Patent Literature 3

Summary of the Invention

Problem to be Solved by the Invention

[0004] An object of the present invention is to provide a highly reliable semiconductor device.

Means for Solving the Problem

[0005] A semiconductor device according to an embodiment comprises: a pellet; a first electric conductor and a second electric conductor that sandwich the pellet in a first direction; a first bonding material that bonds the pellet and the first electric conductor; and a second bonding material that bonds the pellet and the second electric conductor, wherein a first surface of the first electric conductor facing the pellet has a plurality of protrusions overlapping the pellet when viewed in the first direction, and a groove provided so as to surround the pellet, a designed value of heights of the plurality of protrusions is a first value, and a volume of the groove is based on a volume of a portion sandwiched between the pellet and the first electric conductor when a first height between the pellet and the first electric conductor is a second value larger than the first value.

Brief Description of the Drawings

[0006] [Figure 1] A perspective view showing an example of the external appearance of a semiconductor device according to the embodiment. [Figure 2] An exploded view showing an example of the internal structure of a semiconductor device according to an embodiment. [Figure 3] A plan view showing an example of a planar layout of a semiconductor device according to an embodiment. [Figure 4] A cross-sectional view along line IV-IV in Figure 3, showing an example of the cross-sectional structure of a semiconductor device according to the embodiment. [Figure 5] A plan view showing an example of a planar layout of a semiconductor device according to the first modified example. [Figure 6] A plan view showing an example of a planar layout of a semiconductor device according to the second modified example. [Figure 7] A plan view showing an example of a planar layout of a semiconductor device according to the third modified example. [Modes for carrying out the invention]

[0007] Embodiments are described below with reference to the drawings. The dimensions and proportions in the drawings are not necessarily the same as those in reality.

[0008] In the following explanation, components having substantially the same function and structure will be assigned the same reference numeral. When elements with similar structures need to be specifically distinguished, different letters or numbers may be added to the end of the same reference numeral.

[0009] 1 Embodiment A semiconductor device according to an embodiment will be described.

[0010] Figure 1 is a perspective view showing an example of the external appearance of a semiconductor device according to an embodiment. The semiconductor device 1 is an industrial power device. The semiconductor device 1 has, for example, a thin rectangular parallelepiped shape. Hereinafter, the thickness direction of the semiconductor device 1 will be referred to as the vertical direction or the Z direction. Also, if the components of the semiconductor device 1 have two faces opposite each other in the vertical direction, these two faces will be referred to as the bottom surface and the top surface, respectively. Also, two mutually perpendicular directions in a plane perpendicular to the Z direction will be referred to as the X direction and the Y direction.

[0011] The semiconductor device 1 comprises a collector electrode 10, two emitter electrodes 20, two gate electrodes 30, and a encapsulating material 40. Each of the collector electrode 10, the two emitter electrodes 20, and the two gate electrodes 30 has a portion exposed to the outside of the encapsulating material 40 as a terminal responsible for electrical connection to the outside.

[0012] The collector electrode 10 and the two emitter electrodes 20 are provided so as to be exposed on the lower and upper surfaces of the sealing material 40, respectively. For example, the exposed surface of the collector electrode 10 and the exposed surfaces of each of the two emitter electrodes 20 are flush with the lower and upper surfaces of the sealing material 40, respectively. Viewed in the thickness direction, the exposed surface of each of the two emitter electrodes 20 is contained within the exposed surface of the collector electrode 10.

[0013] The two gate electrodes 30 are provided so as to be exposed on the side surface of the sealing material 40. For example, the two gate electrodes 30 protrude from the side surface of the sealing material 40.

[0014] The sealing material 40 is an insulating member that physically and electrically protects the internal structure of the semiconductor device 1 from the outside. The sealing material 40 forms the outer shape of the semiconductor device 1.

[0015] FIG. 2 is an exploded view showing an example of the internal structure of the semiconductor device according to the embodiment. FIG. 2 schematically illustrates the internal structure of the semiconductor device 1 exploded along the thickness direction. Note that illustration of the sealing material 40 is omitted in FIG. 2. As the internal structure, in addition to a collector electrode 10, two emitter electrodes 20, and two gate electrodes 30, the semiconductor device 1 further includes two bonding materials 50, two pellets 60, two bonding materials 70, and two wires 80.

[0016] Each of the collector electrode 10 and the emitter electrode 20 is, for example, a copper plate having a thickness of approximately 1.5 mm. The lower surface of the collector electrode 10 corresponds to a surface of the collector electrode 10 exposed from the sealing material 40. For example, the lower surface of the collector electrode 10 has flatness over the entire surface. A more specific configuration of the collector electrode 10 will be described later. The upper surface of the emitter electrode 20 corresponds to a surface of the emitter electrode 20 exposed from the sealing material 40. For example, the upper surface of the emitter electrode 20 has flatness over the entire surface.

[0017] Two bonding materials 50 are provided spaced apart from each other on the upper surface of the collector electrode 10. The bonding material 50 is, for example, plate-shaped solder. The bonding material 50 is provided between the collector electrode 10 and a corresponding one of the pellets 60.

[0018] The pellet 60 is a power semiconductor chip. Specifically, for example, the pellet 60 is an Insulated Gate Bipolar Transistor (IGBT), or a Metal-Oxide-Silicon Field-Effect Transistor (MOSFET) using silicon carbide (SiC). Note that when the pellet 60 is a MOSFET using SiC, the collector electrode 10 and the emitter electrode 20 shall be read as a drain electrode and a source electrode, respectively.

[0019] The lower surface of the pellet 60 is used as an electrode corresponding to a collector. The lower surface of the pellet 60 is electrically connected to the collector electrode 10 via the bonding material 50. The area of the lower surface of the pellet 60 is smaller than that of the collector electrode 10. A pad corresponding to an emitter and a pad corresponding to a gate are provided on the upper surface of the pellet 60. The area of the upper surface of the pellet 60 is larger than that of the emitter electrode 20.

[0020] On the upper surface of the pellet 60, in a region that includes the pad corresponding to the emitter and excludes the pad corresponding to the gate, the corresponding bonding material 70 is provided. The bonding material 70 is, for example, plate-shaped solder. The corresponding emitter electrode 20 is provided on the upper surface of the bonding material 70.

[0021] On the upper surface of the pellet 60, one end of the corresponding wire 80 is provided on the pad corresponding to the gate. The wire 80 is a bonding wire. The other end of the wire 80 is connected to the corresponding gate electrode 30.

[0022] The two pellets 60 are provided, for example, so as to be aligned in the Y direction.

[0023] With the above configuration, inside the semiconductor device 1, the three terminals used for input and output of the pellet 60 are electrically connected to the collector electrode 10, the emitter electrode 20, and the gate electrode 30, respectively. The bonding materials 50 and 70 are responsible for electrical connection between the pellet 60 and the terminals, and have a function of dissipating heat generated in the pellet 60 in the vertical direction.

[0024] In addition, although the case where two pellets 60 are provided in the semiconductor device 1 has been described in FIG. 1 and FIG. 2, the present invention is not limited thereto. The number of pellets 60 provided in the semiconductor device 1 may be one, or may be three or more.

[0025] Figure 3 is a plan view showing an example of the planar layout of the semiconductor device according to the embodiment. Figure 4 is a cross-sectional view along line IV-IV in Figure 3, showing an example of the cross-sectional structure of the semiconductor device according to the embodiment. Note that the sealing material 40 is not shown in Figures 3 and 4.

[0026] On the upper surface of the collector electrode 10, for example, four collector protrusions P corresponding to each pellet 60 are provided. That is, if the semiconductor device 1 contains two pellets 60, eight collector protrusions P are provided on the upper part of the collector electrode 10. The collector protrusions P corresponding to each pellet 60 are provided so as to overlap with the pellet 60 when viewed in the Z direction. With this configuration, each pellet 60 can come into contact with the upper surface of the four collector protrusions P. Note that the number of collector protrusions P corresponding to each pellet 60 is not limited to four. The number of collector protrusions P corresponding to each pellet 60 can be three or more.

[0027] The height t1 of the collector protrusion P in the Z direction is, for example, 100 μm or more. The collector protrusion P on the collector electrode 10 has variation, and the height t1 deviates from the design value. That is, the heights of multiple collector protrusions P are between the minimum and maximum values. For example, if the design value for the height of the collector protrusion P is 150 μm, and the height of the collector protrusion P varies by ±20 μm from the design value, the heights of multiple collector protrusions P may be between 130 μm and 170 μm. Also, for example, if the design value is 200 μm, and the height of the collector protrusion P varies by ±20 μm from the design value, the heights of multiple collector protrusions P may be between 180 μm and 220 μm. The maximum and minimum values ​​of the height can be determined, for example, based on the design value or machining accuracy.

[0028] The bonding material 50 is provided to fill the space between each pellet 60 supported by the collector projection P and the upper surface of the collector electrode 10. As a result, the thickness of the bonding material 50 is 100 μm or more, similar to the height t1 of the collector projection P.

[0029] For example, two grooves G are provided on the upper part of the collector electrode 10. Each groove G is provided corresponding to a pellet 60. As a result, the two grooves G are arranged, for example, aligned in the Y direction. The height of the upper surface of the collector electrode 10, excluding the collector projection P and the grooves G, is, for example, approximately the same.

[0030] Each groove G is provided so as to surround a rectangular region R when viewed in the Z direction. The width in the Y direction of the portion of groove G extending along the X direction (the portion of groove G tangent to the edge of region R extending in the X direction) and the width along the X direction of the portion of groove G extending along the Y direction (the portion of groove G tangent to the edge of region R extending in the Y direction) are, for example, approximately equal. In the following description, the width in the Y direction of the portion of groove G extending along the X direction and the width along the X direction of the portion of groove G extending along the Y direction will also be simply referred to as the width of groove G.

[0031] Viewed in the Z direction, the area of ​​each region R is larger than the area of ​​the lower surface of the pellet 60. The lower surface of each pellet 60 is included in the region R corresponding to that pellet 60 when viewed in the Z direction. In the X direction, the width w1 between the pellet 60 and the groove G at both ends of the pellet 60 is, for example, about 200 μm. Although not shown in the figures, in the Y direction, the width between the pellet 60 and the groove G at both ends of the pellet 60 is also, for example, about 200 μm. With this configuration, the collector projection P corresponding to each pellet 60 is provided within the region R corresponding to that pellet 60.

[0032] The groove G may contain a portion of the bonding material 50. To elaborate, the semiconductor device 1 with the above configuration is formed by filling the space between the collector electrode 10 and the pellet 60 with bonding material 50, filling the space between the pellet 60 and the emitter electrode 20 with bonding material 70, and then pressing the assembly of these components vertically using a weight (not shown). As a result, in this process, a force acts on the bonding material 50, pushing it out from between the pellet 60 and the collector electrode 10. The amount of bonding material 50 used to fill the space between the collector electrode 10 and the pellet 60 is set, for example, to fill the space between the collector electrode 10 and the pellet 60 when the height of all collector protrusions P is the maximum height of the collector protrusions P. With this forming method, excess bonding material 50 may flow out to the outside of the pellet 60 when viewed in the Z direction. The portion of the bonding material 50 that has flowed out may be contained inside the groove G.

[0033] The groove G is constructed based on the volume of the portion sandwiched between the collector electrode 10 and the pellet 60 when the height of the collector protrusion P (and the height of the portion sandwiched between the collector electrode 10 and the pellet 60) is at its maximum value, taking into consideration the formation of the portion of the adhesive material 50 that has flowed out as described above. More specifically, the groove G is constructed to have a volume greater than or equal to the volume obtained by subtracting the volume of the portion when the height of the collector protrusion P is at its design value from the volume of the portion when the height of the collector protrusion P is at its maximum value. In this configuration of the groove G, the volume of the groove G may be based on the average or median value of the heights of multiple collector protrusions P, for example, instead of the design value of the height of the collector protrusion P.

[0034] According to the embodiment, the upper part of the collector electrode 10 includes a groove G that surrounds the pellets 60 outside of the pellets 60 when viewed from above, and a collector projection P that overlaps with the pellets 60. The volume of the groove G is based on the volume of the portion sandwiched between the collector electrode 10 and each pellet 60 when the height of the collector projection P is at its maximum value. More specifically, the groove G is configured to have a volume greater than or equal to the volume obtained by subtracting the volume of the sandwiched portion when the height of the collector projection P is at its standard value from the volume of the sandwiched portion when the height of the collector projection P is at its maximum value. With this configuration, even if solder flows out from between the collector electrode 10 and the pellets 60 when pressed vertically during the manufacturing process, it is possible to suppress it from flowing out beyond the groove G. This suppresses excessive spreading of solder on the upper surface of the collector electrode 10. Therefore, it is possible to suppress the sealing material 40 from becoming easily peeled off due to solder that does not adhere to the sealing material 40 spreading on the upper surface of the collector electrode. Therefore, the degradation of the reliability of semiconductor device 1 can be suppressed.

[0035] 2. Variations Next, a modified semiconductor device will be described. In the following, the differences between the configuration of the modified semiconductor device and the configuration of the semiconductor device according to the embodiment will be primarily described. Configurations equivalent to those of the embodiment will be omitted as appropriate.

[0036] 2.1 First Variation The first modified example differs from the embodiment in that, when viewed in the Z direction, the groove includes a portion that is wider than the rest of the groove.

[0037] Figure 5 is a plan view showing an example of a planar layout of a semiconductor device according to the first modified example. Figure 5 corresponds to Figure 3. Note that in Figure 5, the emitter electrode 20, gate electrode 30, and wire 80 are not shown. Also, in Figure 5, the area where the pellet 60 is provided is indicated by a dotted line.

[0038] In the semiconductor device 1a according to the first modified example, in the X direction, the first portion of the collector electrode 10 provided on one end side of the pellet 60 has a width w2. The first portion is the part between one end of the pellet 60 and the edge of the collector electrode 10 on one end side in the X direction. Also, in the X direction, the second portion of the collector electrode 10 provided on the other end side of the pellet 60 has a width w3. The second portion is the part between the other end of the pellet 60 and the edge of the collector electrode 10 on the other end side in the X direction. Also, in the Y direction, the third portion of the collector electrode 10 provided on one end side of the pellet 60 on the one end side of the two pellets 60 has a width w4. The third portion is the part between one end of the pellet 60 on the one end side and the edge of the collector electrode 10 on one end side in the Y direction. Also, in the Y direction, the fourth portion of the collector electrode 10 provided on the other end side of the pellet 60 on the other end side of the two pellets 60 has a width w5. The fourth portion is the portion in the Y direction between the other end of the pellet 60 and the other end of the collector electrode 10. Widths w2 and w3 are wider than, for example, widths w4 and w5.

[0039] The portion of the groove Ga extending along the Y direction includes, for example, a portion WPa that is wider than the rest of the groove Ga. That is, in the first and second portions which are wider than the third and fourth portions, the groove Ga includes the wider portion WPa. The width of the groove Ga in the rest of the groove, excluding the portion WPa, is, for example, equivalent. Note that the example shown in Figure 5 shows a case where each groove Ga has two portions WPa. However, it is not limited to this. The number of portions WPa in each groove Ga can be one or three or more.

[0040] In the above description, the first part, second part, third part, and fourth part may be defined as the part of the collector electrode 10 provided on one end side of region Ra inside the groove Ga in the X direction, the part of the collector electrode 10 provided on the other end side of region Ra in the X direction, the part of the collector electrode 10 provided on one end side of region Ra of one of the two regions Ra in the Y direction, and the part of the collector electrode 10 provided on the other end side of region Ra of the other end of the two regions Ra in the Y direction. In this case, the first part, second part, third part, and fourth part are defined as the part in the X direction between the side of one end of region Ra and the side of one end of the collector electrode 10, the part in the X direction between the side of the other end of region Ra and the side of the other end of the collector electrode 10, the part in the Y direction between the one end of region Ra and the side of one end of the collector electrode 10, and the part in the Y direction between the other end of region Ra and the side of the other end of the collector electrode 10.

[0041] The first modification also produces the same effects as the embodiment.

[0042] Furthermore, the groove Ga includes a wider portion WPa in the first and second portions, which are wider than the third and fourth portions. This makes it possible to secure a portion of the collector electrode 10a that is bonded to the encapsulant 40 in the region outside the groove Ga, while suppressing an increase in the size of the semiconductor device 1a. To add to this, for example, if the groove includes a wider portion in the third and fourth portions, which are narrower than the first and second portions, it may not be possible to secure a sufficient portion of the collector electrode that is bonded to the encapsulant outside the groove. According to the first modified example, with the above configuration, it is possible to secure a portion of the collector electrode that is bonded to the encapsulant without increasing the size of the collector electrode and the semiconductor device.

[0043] 2.2 Second Variation The second modified example differs from the embodiment in that the collector electrode has an unwetting region.

[0044] Figure 6 is a plan view showing an example of a planar layout of a semiconductor device according to the second modified example. Figure 6 corresponds to Figures 3 and 5. In Figure 6, as with Figure 5, the emitter electrode 20, gate electrode 30, and wire 80 are omitted from the illustration. Also in Figure 6, as with Figure 5, the area where the pellet 60 is provided is indicated by a dotted line.

[0045] In the semiconductor device 1b according to the second modification, an unwetting region NWb is provided in the region Rb inside the groove Gb of the collector electrode 10b. The unwetting region NWb is a region where solder does not flow easily and is difficult to apply. The unwetting region NWb is formed by applying a resist or performing an oxidation treatment with a laser. The unwetting region NWb is partially provided on the outer periphery of the region Rb inside the groove Gb. In the following description, the region Rb in which the unwetting region NWb is not provided will be called the wetted region Wb.

[0046] The wetted region Wb is provided so as to be in contact with the groove Gb. In the example shown in Figure 6, the wetted region Wb is provided so as to be in contact with the portion of the groove Gb extending along the two X directions and the portion of the groove Gb extending along the two Y directions. Note that the outer periphery of the region Rb inside the groove Gb only needs to have an unwetted region NWb and a wetted region Wb in contact with the groove Gb, and the number of places where the wetted region Wb is in contact with the groove Gb is not limited to four. The number of places where the wetted region Wb is in contact with the groove Gb may be one to three, or five or more.

[0047] The second modification also produces the same effects as the embodiment.

[0048] Furthermore, according to the second modification, the non-wetting region NWb and the wetted region Wb in contact with the groove Gb are provided on the outer periphery of the region Rb located inside the groove Gb. This makes it possible to limit the area from which solder flows out when it flows out between the collector electrode 10 and the pellet 60 during the manufacturing process. As a result, it is possible to suppress excessive solder flow from between the collector electrode 10 and the pellet 60. Consequently, it is possible to suppress the occurrence of solder shrinkage cavities (cracks, etc.).

[0049] 2.3 Third Variation The third modification differs from the first modification in that the collector electrode has an unwetting region.

[0050] Figure 7 is a plan view showing an example of a planar layout of a semiconductor device according to the third modified example. Figure 7 corresponds to Figures 3, 5, and 6. In Figure 7, as with Figures 5 and 6, the emitter electrode 20, gate electrode 30, and wire 80 are omitted from the illustration. Also in Figure 7, as with Figures 5 and 6, the area where the pellet 60 is provided is indicated by a dotted line.

[0051] In the semiconductor device 1c according to the third modification, similar to the portion WPa in the groove Ga of the first modification, the wider portion WPc in the groove Gc is provided in the first and second portions, which are wider than the third and fourth portions. That is, the wider portion WPc is included in the portion of the groove Gc that extends along the Y direction.

[0052] Furthermore, in the semiconductor device 1c according to the third modified example, similar to the unwetting region NWb in the second modified example, the unwetting region NWc is partially provided on the outer periphery of region Rc, which is inside the groove Gc. The wetting region Wc is provided so as to be in contact with the groove Gc. In the third modified example, the wetting region Wc is provided corresponding to the wide portion WPc. More specifically, each of the wetting regions Wc is in contact with the corresponding portion WPc. The length of each wetting region Wc along the Y direction is, for example, shorter than the length of the corresponding wide portion WPc along the Y direction. Viewed in the X direction, each of the wetting regions Wc is provided so as to overlap with the corresponding wide portion WPc. In the above configuration, the unwetting region NWc is provided throughout the outer periphery of region Rc, excluding the wetting region Wc that is in contact with the portion WPc.

[0053] According to the third modification, the same effects as those of the embodiment, the first modification, and the second modification are achieved.

[0054] Furthermore, according to the third modification, the wetted region Wc is provided so as to be in contact with the corresponding wider portion WPc. This makes it easier for solder to flow out from between the collector electrode 10 and the pellet 60 during the manufacturing process, via the portion of the wetted region Wc that is in contact with the groove Gc, into the wider portion WPc. This configuration also makes it possible to suppress solder from flowing outside the groove Gc during the manufacturing process when solder flows out from between the collector electrode 10 and the pellet 60.

[0055] 3. Others While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0056] 1, 1a, 1b, 1c… Semiconductor equipment 10, 10a, 10b, 10c... Collector electrodes 20…Emitter electrode 30… Gate stop 40… Sealing material 50,70…bonding material 60...pellets 80... Wire

Claims

1. Pellets and A first conductor and a second conductor sandwich the pellet in a first direction, A first bonding material for bonding the pellet and the first conductor, A second bonding material for bonding the pellet and the second conductor, Equipped with, The first surface of the first conductor facing the pellet has, when viewed in the first direction, a plurality of protrusions that overlap with the pellet, and grooves that surround the pellet. The design value for the height of the aforementioned multiple protrusions is the first value. The volume of the groove is based on the volume of the portion sandwiched between the pellet and the first conductor when the first height between the pellet and the first conductor is a second value greater than the first value. Semiconductor equipment.

2. The volume of the groove is greater than or equal to the volume obtained by subtracting the volume of the sandwiched portion when the first height is the first value from the volume of the sandwiched portion when the first height is the second value. The semiconductor device according to claim 1.

3. The second value is the maximum value in the variation of the heights of the plurality of protrusions. The semiconductor device according to claim 1.

4. The aforementioned multiple protrusions number three or more. The semiconductor device according to claim 1.

5. In the first conductor, The width of the first portion outside the aforementioned pellet is the first width, The width of the second portion, which is outside the pellet and differs from the first portion, is a second width that is narrower than the first width. The groove includes, in the first portion, a first groove portion having a width wider than the width of the groove in the second portion. The semiconductor device according to any one of claims 1 to 4.

6. Viewed in the first direction, the region inside the groove in the first conductor is provided with a partially wetted region on the outer periphery and a wetted region in contact with the groove. The semiconductor device according to any one of claims 1 to 4.

7. The aforementioned unwetting region is the region where resist coating or oxidation treatment has been performed. The semiconductor device according to claim 6.

8. Viewed in the first direction, the region inside the groove in the first conductor is provided with a partially wetted region on the outer periphery and a wetted region in contact with the first groove portion. The semiconductor device according to claim 5.

9. The non-wetting region is provided on the outer periphery, excluding the wetted region. The semiconductor device according to claim 8.

10. The first and second bonding materials include solder. The semiconductor device according to claim 1.

11. The pellets, the first bonding material, and the second bonding material are sealed with a sealing material. The first conductor and the second conductor each have at least a portion exposed from the sealing material. The semiconductor device according to claim 1.

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