Semiconductor device and method for fabricating semiconductor device

Abstract

This semiconductor device comprises: a conductor plate having a conductor plate thin film, which is a metal thin film; and a semiconductor element having a semiconductor element thin film, which is a metal thin film. The conductor plate and the semiconductor element are configured such that the conductor plate thin film and the semiconductor element thin film are directly bonded, and a conductor plate first end, which is a first end of the conductor plate, and a semiconductor element first end, which is a first end of the semiconductor element, are disposed in the same plane.

Description

Semiconductor device and method for manufacturing the same

[0001] The present invention relates to a semiconductor device and a method for manufacturing a semiconductor device.

[0002] Semiconductor devices are required to have various features such as small size, high performance, low heat generation, etc. Patent Document 1 discloses a method for manufacturing a semiconductor device, in which a lead frame is provided between a first frame and a second frame facing the first frame, the lead frame being integral with the first frame and the second frame and having a plurality of element mounting portions in row and column directions, the element mounting portions having at least an island and a plurality of leads provided adjacent to the island, a BIP type IC chip or a MOS type IC chip is mounted on the island of the element mounting portion, and the leads of the element mounting portion and the BIP type IC chip or the MOS type IC chip are electrically connected, the lead frame is placed in a mold, and a flat upper surface forming a sealing space of the upper mold and a flat upper surface of the upper mold are formed. A method for manufacturing a semiconductor device is disclosed, characterized in that an insulating resin made of a thermosetting resin is transfer molded by pressing the upper mold and a lower mold arranged opposite the upper mold so that multiple element mounting portions are provided in a cavity made of four flat side surfaces located around the upper mold, and the lead frame integrated with the insulating resin at locations corresponding to the dicing lines around the element mounting portions is diced using a dicing device that has a higher alignment accuracy with the lead frame than the alignment accuracy with a molding mold made of the upper mold and the lower mold, thereby forming a substantially hexahedron.

[0003] Japanese Patent Application Laid-Open No. 2009-065201

[0004] In the invention described in Patent Document 1, the thickness of the semiconductor device is large.

[0005] A semiconductor device according to a first aspect of the present invention comprises a conductor plate having a conductor plate thin film that is a metal thin film, and a semiconductor element having a semiconductor element thin film that is a metal thin film, wherein the conductor plate and the semiconductor element are directly bonded to each other, and a conductor plate first end that is a first end of the conductor plate and a semiconductor element first end that is a first end of the semiconductor element are arranged on the same plane.A semiconductor device manufacturing method according to a second aspect of the present invention is a method for manufacturing a semiconductor device in which a conductor plate and a semiconductor element are bonded to each other, comprising: a thin film forming step of forming a conductor plate thin film that is a metal thin film on the conductor plate and a semiconductor element thin film that is a metal thin film having the same composition as the conductor plate thin film on the semiconductor element; and a bonding step of atomic diffusion bonding the conductor plate thin film and the semiconductor element thin film, wherein the bonding step is a step of bonding a semiconductor wafer before dicing into multiple semiconductor dies to the conductor plate, and further includes a dicing step after the bonding step of dividing the semiconductor wafer together with the conductor plate to manufacture multiple semiconductor devices.

[0006] According to the present invention, the thickness of the semiconductor device can be reduced.

[0007] 1 is a cross-sectional view of a semiconductor device according to an embodiment; 2 is a diagram showing a first step in manufacturing the semiconductor device; 3 is a diagram showing a second step in manufacturing the semiconductor device; 4 is a diagram showing a third step in manufacturing the semiconductor device; 5 is a diagram showing a fourth step in manufacturing the semiconductor device; 6 is a diagram showing a sixth step in manufacturing the semiconductor device;

[0008] First Embodiment A first embodiment of a semiconductor device will be described below with reference to FIGS.

[0009] (Configuration) FIG. 1 is a cross-sectional view of a semiconductor device 1. For ease of explanation, FIG. 1 depicts mutually orthogonal X, Y, and Z axes. The semiconductor device 1 includes a semiconductor element 10, a first conductor plate 30, and a second conductor plate 40. Hereinafter, the first conductor plate 30 and the second conductor plate 40 will be collectively referred to as "conductor plates" 8. The semiconductor element 10, the first conductor plate 30, and the second conductor plate 40 are stacked in the Z-axis direction. The semiconductor element 10 is flat and has a first surface 11 at the top and a second surface 12 at the bottom. The semiconductor element 10 has a first electrode 11P on the first surface 11 and a second electrode 12P on the second surface 12. However, the first electrode 11P and the second electrode 12P are not shown in FIG. 1.

[0010] A first semiconductor element thin film 23, which is a metal thin film, is formed on the first surface 11 of the semiconductor device 1. The surface of the first electrode 11P is also covered with the first semiconductor element thin film 23. A second semiconductor element thin film 21, which is a metal thin film, is formed on the second surface 12 of the semiconductor device 1. The surface of the second electrode 12P is also covered with the second semiconductor element thin film 21. A first conductor plate thin film 24, which is a metal thin film, is formed on the lower surface of the first conductor plate 30 in the figure. A second conductor plate thin film 22, which is a metal thin film, is formed on the upper surface of the second conductor plate 40 in the figure. The compositions of these metal thin films will be described later.

[0011] The first conductor plate thin film 24 and the first semiconductor element thin film 23 are directly bonded together. This bonding is, for example, atomic diffusion bonding. The first conductor plate 30 is bonded to the first electrode 11P through this bonding. The second conductor plate thin film 22 and the second semiconductor element thin film 21 are directly bonded together. This bonding is, for example, atomic diffusion bonding. The second conductor plate 40 is bonded to the second electrode 12P through this bonding. Hereinafter, the first semiconductor element thin film 23 and the second semiconductor element thin film 21 will be collectively referred to as the "semiconductor element thin film" 81. Furthermore, the first conductor plate thin film 24 and the second conductor plate thin film 22 will be collectively referred to as the "conductor plate thin film" 82. The semiconductor element 10 is a small piece cut out from a silicon wafer and is also called a "silicon die" or "die."

[0012] At least one side of the semiconductor device 1 has a cut surface 5 formed on the same plane. However, in FIG. 1 , the ends on the positive and negative sides of the X axis have cut surfaces 5 parallel to the YZ plane, i.e., first end surface 5A and second end surface 5B. In other words, the ends on the negative side of the X axis of the first conductor plate 30, the second conductor plate 40, and the semiconductor element 10 are all arranged such that the ends on the positive side of the X axis are located on the first end surface 5A, and the ends on the positive side of the X axis are located on the second end surface 5B. The reason why the ends are arranged on the same plane will be explained later.

[0013] The end on the left side of the first conductor plate 30 in the drawing is called the first conductor plate first end 30L. The end on the left side of the second conductor plate 40 in the drawing is called the second conductor plate first end 40L. The end on the left side of the semiconductor element 10 in the drawing is called the semiconductor element first end 10L. The end on the right side of the first conductor plate 30 in the drawing is called the first conductor plate second end 30R. The end on the right side of the second conductor plate 40 in the drawing is called the second conductor plate second end 40R. The end on the right side of the semiconductor element 10 in the drawing is called the semiconductor element second end 10R. However, for convenience of drawing, the first conductor plate second end 30R, the second conductor plate second end 40R, and the semiconductor element second end 10R are not shown in FIG. 1 .

[0014] 2 to 7 are diagrams illustrating a method for manufacturing the semiconductor device 1. Each of FIGS. 2 to 7 shows the first to sixth steps, and for ease of explanation, each of FIGS. 2 to 6, except for FIG. 7, shows both a perspective view and a front view. The second and fourth steps are also called "thin film formation steps," the third and fifth steps are also called "bonding steps," and the sixth step is also called "dicing step."

[0015] 2, the semiconductor wafer 100 and a large second conductor plate 400 with slits are placed in a vacuum chamber. The semiconductor wafer 100 is made up of multiple semiconductor elements 10 connected together as shown in FIG. 1. The large second conductor plate 400 roughly corresponds to multiple second conductor plates 40 connected together as shown in FIG. 1.

[0016] In the second process shown in FIG. 3 , a second semiconductor wafer thin film 210 is formed on the semiconductor wafer 100 inside a vacuum chamber, and a large second conductor plate thin film 220 is formed on the large second conductor plate 400. The second semiconductor wafer thin film 210 and the large second conductor plate thin film 220 are made of any of W (tungsten), Al (aluminum), Cr (chromium), Ni (nickel), Ti (titanium), Ta (tantalum), Cu (copper), Au (gold), Pt (platinum), Fe (iron), Ag (silver), C (carbon), and TiO2 (titanium dioxide). However, they may be made of several types arbitrarily selected from these, or alloys with other elements. The second semiconductor wafer thin film 210 and the large second conductor plate thin film 220 may be a single layer or two or more layers. The thickness of the second semiconductor wafer thin film 210 and the large second conductor plate thin film 220 is 1 nm to 1000 nm.

[0017] In the third step shown in Figure 4, the semiconductor wafer 100 on which the second semiconductor wafer thin film 210 is formed and the slit-shaped large second conductor plate 400 on which the large second conductor plate thin film 220 is formed are removed from the vacuum chamber. The second semiconductor wafer thin film 210 and the large second conductor plate thin film 220 are then bonded together at a pressure of several MPa. This bonding eliminates the interface between the second semiconductor wafer thin film 210 and the large second conductor plate thin film 220. This bonding process does not form intermetallic compounds or heat-affected zones, which occur in bonding involving metal melting, such as solder bonding. Furthermore, this bonding process does not form microvoids, which are often found in sintering processes such as sinter bonding.

[0018] In the fourth process shown in FIG. 5 , a first semiconductor wafer thin film 230 is formed on a semiconductor wafer 100 in a vacuum chamber, and a large first conductor plate thin film 240 is formed on a slitted large first conductor plate 300. The large first conductor plate 300 roughly corresponds to a plurality of first conductor plates 30 connected together as shown in FIG. 1 . The possible compositions of the first semiconductor wafer thin film 230 and the large first conductor plate thin film 240 are as described above. It is essential that the second semiconductor wafer thin film 210 and the large second conductor plate thin film 220 have the same composition, and it is also essential that the first semiconductor wafer thin film 230 and the large first conductor plate thin film 240 have the same composition. However, it is not essential that all four compositions of the second semiconductor wafer thin film 210, the large second conductor plate thin film 220, the first semiconductor wafer thin film 230, and the large first conductor plate thin film 240 be the same.

[0019] In the fifth step shown in FIG. 6 , the semiconductor wafer 100 on which the first semiconductor wafer thin film 230 is formed and the large-sized first conductor plate 300 on which the large-sized first conductor plate thin film 240 is formed are removed from the vacuum chamber. The first semiconductor wafer thin film 230 and the large-sized first conductor plate thin film 240 are then bonded together at a pressure of several MPa. This bonding process forms a bonded body 9 in which the semiconductor wafer 100, the large-sized second conductor plate 400, and the large-sized first conductor plate 300 are integrally bonded together. This bonding process eliminates the interface between the first semiconductor wafer thin film 230 and the large-sized first conductor plate thin film 240. This bonding process does not form intermetallic compounds or heat-affected zones, which are common in bonding processes involving metal melting, such as solder bonding. Furthermore, this bonding process does not form microvoids, which are common in sintering processes such as sinter bonding.

[0020] 7 , the slits 301 in the bonded body 9 are irradiated with laser light 3 to cut the bonded body 9 into small pieces. These small pieces of the bonded body 9 are semiconductor devices 1. The slits 301 can also be called "grooves." The width of the slits 301 is wider than the width of the laser light 3, and the length of the bonded body 9 in the Z-axis direction cut by the laser light 3 is the length obtained by subtracting the depth of the slits 301 formed in the first large conductor plate 300 and the second large conductor plate 400 from the thickness of the bonded body 9 in the Z-axis direction. Because the slits 301 are wider than the laser light 3, the slits 301 remain on the outer periphery of the semiconductor device 1, which is the small pieces after cutting.

[0021] The end faces are aligned, i.e., flush, when cutting with the laser beam 3. Since the first end face 5A and the second end face 5B are formed by cutting with the laser beam 3, the ends of the first conductor plate 30, the second conductor plate 40, and the semiconductor element 10 are arranged on the same plane at the first end face 5A and the second end face 5B.

[0022] 7, four semiconductor elements 10 are lined up in the X-axis direction, and the laser beam 3 is irradiated onto three slits 301 to cut the bonded body 9. Therefore, the two central semiconductor devices 1 are processed on the left and right sides by the laser beam 3, but the left side of the semiconductor device 1 shown on the left end of the figure is not cut by the laser beam 3, and the right side of the semiconductor device 1 shown on the right end of the figure is not cut by the laser beam 3. In other words, the semiconductor devices 1 shown on the left and right ends are processed by the laser beam 3 only on one side in the X-axis direction.

[0023] The first embodiment described above provides the following advantageous effects. (1) The semiconductor device 1 includes a first conductor plate 30 having a first conductor plate thin film 24, which is a metal thin film, and a semiconductor element 10 having a second semiconductor element thin film 21, which is also a metal thin film. The first conductor plate 30 and the semiconductor element 10 are directly bonded to each other at the first conductor plate thin film 24 and the second semiconductor element thin film 21. A first end of the semiconductor element 10, for example, a semiconductor element first end 10L in the negative X-axis direction, and a first end of the first conductor plate 30, for example, a first conductor plate first end 30L, are disposed on the first end surface 5A.

[0024] This offers the following advantages. First, since the conductor plate 8 and the semiconductor element 10 are bonded without using solder, the thickness of the stacked assembly is reduced, allowing for a thinner semiconductor device 1. Second, since thin films are bonded together, thickness variations are less likely to occur in principle, and the thickness precision of the semiconductor device 1 is significantly higher than when using solder. Third, the thermal resistance between the semiconductor element 10 and the conductor plate 8 is low, providing excellent heat dissipation characteristics. Fourth, the heat resistance of the joint between the semiconductor element 10 and the conductor plate 8 is excellent. If solder were to be used, the temperature would need to be kept lower than the melting point of the solder. Fifth, the semiconductor element 10 and the conductor plate 8 can be made the same size in the planar direction, allowing for a more compact semiconductor device 1. If solder were to be used, the conductor plate would need to be larger than the semiconductor element 10, which would hinder miniaturization. The end of the semiconductor element 10 and the end of the conductor plate 8 are arranged on the same plane because the semiconductor element 10 and the conductor plate 8 are cut simultaneously by laser light 3 in the sixth step of manufacturing the semiconductor device 1.

[0025] (2) The semiconductor element 10 is flat. The semiconductor element 10 has a first electrode 11P on a first surface 11 on the positive side of the Z axis, and a second electrode 12P on a second surface 12 opposite the first surface 11. The conductor plate 8 includes a first conductor plate 30 bonded to the first electrode 11P and a second conductor plate 40 bonded to the second electrode 12P. Therefore, the first conductor plate 30, the second conductor plate 40, and the semiconductor element 10 have cut surfaces formed on the same plane along at least one side. The semiconductor element 10 is sandwiched between the first conductor plate 30 and the second conductor plate 40, and both the semiconductor element 10 and the first conductor plate 30 and the semiconductor element 10 and the second conductor plate 40 can be directly bonded to each other.

[0026] (3) The first end surface 5A and the second end surface 5B include slits 301 formed in advance in the conductive plate 8. This reduces the time required for the sixth step and reduces the strain applied to the conductive plate 8 and the semiconductor element 10 during cutting.

[0027] (4) The bonded conductor plate thin film 82 and semiconductor element thin film 81 have the same composition. The conductor plate thin film 82 and semiconductor element thin film 81 contain at least any of W, Al, Cr, Ni, Ti, Ta, Cu, Au, Pt, Fe, Ag, and TiO2.

[0028] (5) The first conductor plate second end 30R, which is the end of the first conductor plate 30 on the positive side of the X axis, and the semiconductor element second end 10R of the semiconductor element 10 are arranged on a second end face 5B different from the first end face 5A. Therefore, the first conductor plate 30 and the semiconductor element 10 have multiple end faces arranged on the same plane. Note that while only the cross sections of the end faces in the X axis direction are described in FIGS. 1 and 2, the end faces in the Y axis direction may also have a similar configuration. In other words, the conductor plate 8 and the semiconductor element 10 may have their respective end faces arranged on the same plane at a total of four locations, both ends of the X axis and both ends of the Y axis.

[0029] (7) In the semiconductor device 1, the conductor plate 8 and the semiconductor element 10 are bonded to each other. The manufacturing method of this semiconductor device 1 is as follows. The manufacturing method of the semiconductor device 1 includes the first to sixth steps as described with reference to FIGS. 2 to 7. The second and fourth steps are thin-film formation steps in which a conductor plate thin film 82, which is a metal thin film, is formed on the conductor plate 8, and a semiconductor element thin film 81, which is a metal thin film having the same composition as the conductor plate thin film 82, is formed on the semiconductor wafer 100 to which the semiconductor element 10 is connected. The third and fifth steps are bonding steps in which the conductor plate thin film 82 and the semiconductor element thin film 81 are atomic diffusion bonded. This bonding step is a step in which the semiconductor wafer 100 is bonded to the conductor plate 8 before being diced into multiple semiconductor elements 10. The sixth step is a dicing step, which is performed after the bonding step, in which the semiconductor wafer 100 is divided together with the conductor plate 8 to manufacture multiple semiconductor devices 1. This allows for efficient manufacturing of small semiconductor devices 1 that are thin, have high thickness precision, low thermal resistance, and excellent heat resistance.

[0030] (Variation 1) The first conductor plate 30 and the second conductor plate 40 may have an insulating plate on the end surface opposite the semiconductor element 10. Atomic diffusion bonding can be used to bond the conductor plate and the insulating plate, as in the case of bonding the conductor plate and the semiconductor element 10.

[0031] 8 is a cross-sectional view of the semiconductor device 1 in Modification 1. The configuration of the first conductor plate 30 to the second conductor plate 40 in the center of the figure is the same as in the first embodiment. The first conductor plate 30 has a first conductor plate second thin film 27, which is a thin metal film, on its end surface on the positive side of the Z axis. The second conductor plate 40 has a second conductor plate second thin film 25, which is a thin metal film, on its end surface on the negative side of the Z axis. The first insulating plate 71 shown at the top of the figure has a first insulating plate thin film 28, which is a thin metal film, on its end surface on the negative side of the Z axis. The second insulating plate 72 shown at the bottom of the figure has a second insulating plate thin film 26, which is a thin metal film, on its end surface on the positive side of the Z axis.

[0032] The first conductor plate second thin film 27 and the first insulating plate thin film 28 have the same composition. The composition candidates are as described above. The second conductor plate second thin film 25 and the second insulating plate thin film 26 have the same composition. The composition candidates are as described above. In this modification, at least one end of each of the five components, the first conductor plate 30, the second conductor plate 40, the semiconductor element 10, the first insulating plate 71, and the second insulating plate 72, is arranged in the same plane. In FIG. 8 , the five ends on the negative side of the X axis are arranged on the first end surface 5A, and the ends on the positive side of the X axis are arranged on the second end surface 5B. According to this modification 1, a semiconductor device 1 having high heat dissipation characteristics and insulating properties can be manufactured.

[0033] (Variation 2) In the above-described embodiment, both the first conductor plate 30 and the second conductor plate 40 are atomic diffusion bonded to the semiconductor element 10 via a thin metal film. However, the semiconductor element 10 may be atomic diffusion bonded to only one of the first conductor plate 30 and the second conductor plate 40 via a thin metal film. In this case, the other can be connected to the conductor plate using any method, for example, a solder material.

[0034] FIG. 9 is a cross-sectional view of a semiconductor device 1 according to Modification 2. The configuration of the lower half of the figure, specifically the connection between the semiconductor element 10 and the second conductor plate 40, is achieved by bonding metal thin films together, as in the first embodiment. The first conductor plate 30 is connected to the positive side of the semiconductor element 10 along the Z axis via a solder material 60, and is connected to the gate electrode 42 via a wire 61. The semiconductor element 10, the first conductor plate 30, the second conductor plate 40, and the gate electrode 42 are sealed with a molded resin 62. The first conductor plate 30 in this modification can also be called a "source conductor" connected to the source electrode of the semiconductor element 10. The second conductor plate 40 in this modification can also be called a "drain conductor" connected to the drain electrode of the semiconductor element 10. The ends of the semiconductor element 10 on the positive side of the X axis and the ends on the negative side of the X axis are arranged on the same plane.

[0035] 7 in the embodiment, the laser light 3 is parallel to the Z axis. However, depending on manufacturing circumstances or design, the laser light 3 does not have to be parallel to the Z axis.

[0036] 10 is a cross-sectional view of the semiconductor device 1 in Modification 3. In this modification, in the sixth step, the end of the semiconductor device 1 on the negative X-axis side is irradiated with laser light 3 obliquely, and the end on the positive X-axis side is irradiated parallel to the Z-axis, as in the embodiment. Therefore, the first end surface 5A is oblique to the Z-axis. Even in this case, the ends of the first conductor plate 30, the second conductor plate 40, and the semiconductor element 10 on the negative X-axis side are arranged on the same plane as the first end surface 5A.

[0037] The above-described embodiments and modifications may be combined with each other. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

[0038] 1: Semiconductor device 3: Laser light 5: Cut surface 5A: First end surface 5B: Second end surface 9: Bonded body 10: Semiconductor element 11: First surface 11P: First electrode 12: Second surface 12P: Second electrode 21: Second semiconductor element thin film 22: Second conductor plate thin film 23: First semiconductor element thin film 24: First conductor plate thin film 25: Second conductor plate second thin film 26: Second insulating plate thin film 27: First conductor plate second thin film 28: First insulating plate thin film 30: First conductor plate 40: Second conductor plate 100: Semiconductor wafer 210: Second semiconductor wafer thin film 220: Large second conductor plate thin film 230: First semiconductor wafer thin film 240: Large first conductor plate thin film 300 : Large first conductor plate 301 : Slit 400 : Large second conductor plate

Claims

1. A semiconductor device comprising: a conductor plate having a conductor plate thin film which is a metal thin film; and a semiconductor element having a semiconductor element thin film which is a metal thin film, wherein the conductor plate and the semiconductor element are directly bonded to each other, and a conductor plate first end which is a first end of the conductor plate and a semiconductor element first end which is a first end of the semiconductor element are arranged on the same plane.

2. A semiconductor device according to claim 1, wherein the semiconductor element is flat, the semiconductor element has a first electrode on one side and a second electrode on the other side opposite to the one side, the conductor plate includes a first conductor plate joined to the first electrode and a second conductor plate joined to the second electrode, the conductor plate first end includes a first conductor plate first end which is an end of the first conductor plate and a second conductor plate first end which is an end of the second conductor plate, and the first conductor plate first end, the second conductor plate first end and the semiconductor element first end are arranged on the same plane.

3. A semiconductor device according to claim 1, wherein said flush plane includes a groove portion pre-formed in said conductive plate.

4. A semiconductor device according to claim 1, wherein the conductor plate thin film and the semiconductor element thin film have the same composition, and the conductor plate thin film and the semiconductor element thin film contain at least any of W, Al, Cr, Ni, Ti, Ta, Cu, Au, Pt, Fe, Ag, and TiO2.

5. A semiconductor device according to claim 1, wherein a second conductor plate end, which is an end of the conductor plate different from the first conductor plate end, and a second semiconductor element end, which is an end of the semiconductor element different from the first semiconductor element end, are arranged on a second coplanar surface different from the coplanar surface.

6. A method for manufacturing a semiconductor device in which a conductor plate and a semiconductor element are bonded to each other, comprising: a thin film forming step of forming a conductor plate thin film, which is a metal thin film, on the conductor plate, and forming a semiconductor element thin film, which is a metal thin film having the same composition as the conductor plate thin film, on the semiconductor element; and a bonding step of atomic diffusion bonding the conductor plate thin film and the semiconductor element thin film, wherein the bonding step is a step of bonding a semiconductor wafer to the conductor plate before dicing into a plurality of semiconductor dies, and the method further comprises a dicing step of manufacturing a plurality of semiconductor devices by dividing the semiconductor wafer together with the conductor plate after the bonding step.

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