Semiconductor device

Abstract

Provided is a technology capable of improving the reliability of a semiconductor device. The semiconductor device has an insulating layer having a first surface and a second surface opposite the first surface. The semiconductor device has one or more semiconductor elements on the first surface side. The semiconductor device has a first metal sintered body and a second metal sintered body. The first metal sintered body is in contact with the first surface of the insulating layer and the semiconductor element, and bonds the insulating layer and the semiconductor element. The second metal sintered body is in contact with the second surface of the insulating layer.

Description

Technical Field

[0001] This invention relates to semiconductor devices. Background Technology

[0002] For example, Patent Document 1 discloses a technique for bonding a semiconductor chip to a wiring layer bonded to an insulating plate via a metal sintering body.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-27288

[0004] However, in such semiconductor devices, the heat generated by driving the semiconductor chip causes stress at the joints between the wiring layer and the metal sintered body, and at the joints between the wiring layer and the insulating plate. As a result, defects occur at these joints, leading to a decrease in reliability. Summary of the Invention

[0005] Therefore, the present invention was made in view of the above-mentioned problems, and its object is to provide a technology that can improve the reliability of semiconductor devices.

[0006] The semiconductor device of the present invention comprises: an insulating layer having a first surface and a second surface opposite to the first surface; one or more semiconductor elements located on the first surface side; a first metal sintered body that contacts the first surface of the insulating layer and the semiconductor element to bond the insulating layer to the semiconductor element; and a second metal sintered body that contacts the second surface of the insulating layer.

[0007] The effects of the invention

[0008] According to the present invention, the number of bonding portions can be reduced, thereby improving the reliability of the semiconductor device. Attached Figure Description

[0009] Figure 1 This is a top view showing the structure of the semiconductor device according to Embodiment 1.

[0010] Figure 2 This is a cross-sectional view showing the structure of the semiconductor device involved in Embodiment 1.

[0011] Figure 3 This is a cross-sectional view showing the structure of the first related semiconductor device.

[0012] Figure 4 This is a cross-sectional view showing the structure of the semiconductor device involved in Embodiment 2.

[0013] Figure 5 This is a cross-sectional view showing the structure of the semiconductor device involved in Embodiment 3.

[0014] Figure 6 This is a cross-sectional view showing the structure of the semiconductor device involved in Embodiment 4.

[0015] Figure 7 This is a cross-sectional view showing the structure of the semiconductor device involved in Embodiment 5. Detailed Implementation

[0016] The embodiments will now be described with reference to the accompanying drawings. The features described in the following embodiments are illustrative, and not all features are essential. Furthermore, in the following description, the same structural elements are labeled with the same or similar reference numerals in multiple embodiments; the description primarily focuses on different structural elements. Additionally, in the following description, the specific positions and orientations such as "upper," "lower," "left," "right," "front," or "back" do not necessarily correspond to the actual positions and orientations in the implementation.

[0017] <Implementation Method 1>

[0018] Figure 1 This is a top view showing the structure of the semiconductor device according to Embodiment 1. Figure 2 It is along Figure 1 A cross-sectional view along line AA.

[0019] The semiconductor device involved in this embodiment 1 is as follows: Figure 2 The diagram shows an insulating layer 1, a semiconductor element 2, a first metal sintered body 3a, a second metal sintered body 3b, a base plate 4, a housing 5, an adhesive 6, a cover 7, a gate electrode 8, an emitter electrode 10, a wire 11, and an encapsulation material 12, as shown. Figure 1 As shown, the semiconductor device has a collector electrode 9.

[0020] like Figure 2 As shown, the insulating layer 1 has a first surface, i.e., an upper surface, and a second surface, i.e., a lower surface, opposite to the first surface. The insulating layer 1 is, for example, an insulating plate made of ceramic.

[0021] Semiconductor element 2 is located on the upper surface of insulating layer 1. Semiconductor element 2 may include, for example, semiconductor switching elements such as IGBT (Insulated Gate Bipolar Transistor) and MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or diodes such as PND (PN junction Diode) and SBD (Schottky Barrier Diode). In this embodiment 1, the material of semiconductor element 2 is conventional silicon (Si), but it is not limited thereto as will be described later. Furthermore, in this embodiment 1, the number of semiconductor elements 2 is two, but any number greater than or equal to one is acceptable.

[0022] The first sintered metal body 3a contacts the upper surface of the insulating layer 1 and the semiconductor element 2, bonding the insulating layer 1 to the semiconductor element 2. The second sintered metal body 3b contacts the lower surface of the insulating layer 1. Furthermore, metal sintering is a technique that solidifies metal at a temperature below its melting point. The sintered metal body is formed by applying a paste material containing particles of metal such as copper (Cu) or silver (Ag) mixed with a solvent, and then solidifying the paste material through metal sintering. In this embodiment 1, the first sintered metal body 3a serves as a circuit pattern.

[0023] The base plate 4 contacts the second metal sintered body 3b and is bonded to the insulating layer 1 through the second metal sintered body 3b. The housing 5 covers the outer periphery (here, the side) of the semiconductor element 2. Adhesive 6 bonds the housing 5 to the base plate 4. Furthermore, in... Figure 1 and Figure 2 In this example, a hole 5a is provided in the housing 5, and the housing 5 is fixed to the base plate 4 by screws or the like passing through the hole 5a. The cover 7 covers the upper part of the semiconductor element 2. An internal space isolated from the external space is formed by the base plate 4, the housing 5, and the cover 7.

[0024] The gate electrode 8, collector electrode 9, and emitter electrode 10 are integrally disposed with the housing 5, with one end of each electrode located in the external space and the other in the internal space. The semiconductor element 2 is electrically connected to one end of the gate electrode 8 and emitter electrode 10 within the internal space via a wire 11. Additionally, as... Figure 1 As shown, the semiconductor element 2 is electrically connected to one end of the internal space of the collector electrode 9 via the wire 11 and the first metal sintered body 3a. Figure 2 The encapsulation material 12, for example, is made of insulating material and is filled in the internal space where the semiconductor element 2 and the wire 11 are located.

[0025] Such semiconductor devices are used, for example, in inverter circuits that can control the main current flowing sequentially through the collector electrode 9, wire 11, first metal sintered body 3a, semiconductor element 2, wire 11, and emitter electrode 10 by the voltage of the gate electrode 8.

[0026] Here, semiconductor devices related to the semiconductor device according to Embodiment 1 (hereinafter referred to as the first related semiconductor device and the second related semiconductor device) will be described. Figure 3 This is a cross-sectional view showing the structure of the first related semiconductor device.

[0027] Regarding the first related semiconductor device, the insulating layer 1 is bonded to the copper pattern 14a, which is not a metal sintered body, by silver solder 13a, and the insulating layer 1 is bonded to the copper pattern 14b, which is not a metal sintered body, by silver solder 13b. The copper pattern 14a is bonded to the semiconductor element 2 by solder 15a, and the copper pattern 14b is bonded to the base plate 4 by solder 15b.

[0028] Regarding the structure of the first related semiconductor device described above, if the temperature rises and falls within the first related semiconductor device due to the repeated ON / OFF operation of the semiconductor element 2, stress is repeatedly generated at the solders 15a and 15b. As a result, cracks and other defects originating from the solders 15a and 15b occur, leading to a decrease in reliability, such as product lifespan. Furthermore, since silver solders 13a and 13b, whose main component is silver, are used as the bonding materials between the insulating layer 1 and the copper patterns 14a and 14b respectively, whisker formation occurs, further reducing reliability.

[0029] Next, a second related semiconductor device (not shown) will be described. The second related semiconductor device is... Figure 1 Based on the structure of the semiconductor device according to Embodiment 1, conventional wiring layers are provided between the first metal sintered body 3a and the insulating layer 1, and between the second metal sintered body 3b and the insulating layer 1. In this second related semiconductor device, if the aforementioned stresses occur at the joint portions between the wiring layer and the first metal sintered body 3a and the second metal sintered body 3b, and at the joint portion between the wiring layer and the insulating layer 1, there is a problem of deterioration at the joint portions, leading to a decrease in reliability.

[0030] In contrast, in this embodiment 1, the solder 15a and 15b of the first related semiconductor device are not used, thus extending the product lifespan during power cycling, thermal cycling, etc., and improving reliability. Furthermore, since the silver solder 13a and 13b of the first related semiconductor device are not used, whisker formation can be suppressed, further improving the reliability of the semiconductor device.

[0031] Furthermore, the second related semiconductor device has two bonding portions: a bonding portion between the wiring layer and the first metal sintered body 3a and the second metal sintered body 3b, and a bonding portion between the wiring layer and the insulating layer 1. In contrast, in this embodiment 1, the bonding portion between the wiring layer and the insulating layer 1 is eliminated, reducing it to a single bonding portion—the bonding portion between the first metal sintered body 3a and the second metal sintered body 3b and the insulating layer 1. This reduces the number of bonding portions prone to defects due to stress, thereby improving the reliability of the semiconductor device.

[0032] <Implementation Method 2>

[0033] Figure 4 This is a cross-sectional view showing the structure of the semiconductor device involved in Embodiment 2.

[0034] In the semiconductor device according to Embodiment 2, the base plate 4 described in Embodiment 1 is not present, and the second metal sintered body 3b on the lower surface side of the insulating layer 1 serves to diffuse the heat of the base plate 4. With this structure, the number of components can be reduced. Furthermore, miniaturization (reduction in the height of the semiconductor device) is also expected.

[0035] Furthermore, in the semiconductor device according to Embodiment 2, a third metal sintered body 3c is added, which is in contact with the upper surface of the insulating layer 1 and has an adhesive 6 disposed between it and the housing 5. With this structure, the stress from the housing 5 to the insulating layer 1 can be mitigated, thereby suppressing cracks in the insulating layer 1 and improving the reliability of the semiconductor device.

[0036] <Implementation Method 3>

[0037] Figure 5 This is a cross-sectional view showing the structure of the semiconductor device according to Embodiment 3. The semiconductor device according to Embodiment 3 has a metal plate 17 instead of the wires 11 connecting the plurality of semiconductor elements 2 in Embodiment 2. The metal plate 17 is located on the side opposite to the insulating layer 1 relative to the plurality of semiconductor elements 2 and is bonded to the plurality of semiconductor elements 2. Thus, according to Embodiment 3, where the metal plate 17 is used for wiring, compared to a structure where the wires 11 are used for wiring, the power cycle life can be improved or the internal inductance of the semiconductor device can be reduced.

[0038] Furthermore, the bonding material used to join the multiple semiconductor elements 2 to the metal plate 17 can also be solder or the like, but in this embodiment 3, a metal sintered body is used. That is, in the semiconductor device according to this embodiment 3, a fourth metal sintered body 3d is added to join the multiple semiconductor elements 2 to the metal plate 17 and has the same material as the first metal sintered body 3a and the second metal sintered body 3b.

[0039] When the bonding material used to join multiple semiconductor elements 2 to the metal plate 17 is made of a material different from that of the first metal sintered body 3a, these components have different melting points. Therefore, components that are joined or sintered later in the manufacturing process need to use low-melting-point components. In contrast, in this embodiment 3, since the melting points of these components are substantially the same, the sintering of these components can be performed simultaneously. Furthermore, since low-melting-point components are not required, the high-temperature operation of the semiconductor elements 2 can be accommodated.

[0040] Furthermore, in the above description, this embodiment 3 is applied to embodiment 2, but it can also be applied to embodiment 1.

[0041] <Implementation Method 4>

[0042] Figure 6 This is a cross-sectional view showing the structure of the semiconductor device according to Embodiment 4. In Embodiment 4, compared to the structure of Embodiment 3, the thickness of the first metal sintered body 3a below the semiconductor element 2 is greater than or equal to 0.2 mm, making it thicker. With this structure, heat dissipation from the semiconductor element 2 can be achieved efficiently, reducing the maximum internal temperature of the semiconductor device during operation, and thus extending product lifespan, for example.

[0043] Furthermore, the thickness of the first metal sintered body 3a can be greater than the thickness of the second metal sintered body 3b, but it can be greater than the thickness of any of the second metal sintered body 3b, the third metal sintered body 3c, and the fourth metal sintered body 3d. With this structure, the heat generated by the semiconductor element 2 can be diffused horizontally between the semiconductor element 2 and the insulating layer 1, thus achieving efficient heat dissipation. As a result, even if components with low thermal conductivity are used in the structure of the insulating layer 1, the decrease in heat dissipation can be suppressed, thereby improving reliability. In addition, the internal space is typically quite large; therefore, even if the thickness of the first metal sintered body 3a is increased, the size of the semiconductor device can be maintained.

[0044] Furthermore, it is sufficient that the thicknesses of the first metal sintered body 3a and the second metal sintered body 3b are different, and that the thicknesses of any two or more of the first metal sintered body 3a, the second metal sintered body 3b, the third metal sintered body 3c, and the fourth metal sintered body 3d are different. The first metal sintered body 3a to the fourth metal sintered body 3d have effects such as stress relief and improved heat dissipation, but by setting the thicknesses of the first metal sintered body 3a to the fourth metal sintered body 3d to be suitable for their respective effects, their effects can be appropriated.

[0045] Furthermore, in the above description, this embodiment 4 is applied to embodiment 3, but it can also be applied to any of embodiments 1 and 2.

[0046] <Implementation Method 5>

[0047] Figure 7 This is a cross-sectional view showing the structure of the semiconductor device according to Embodiment 5. In Embodiment 5, compared to the structure of Embodiment 4, the first metal sintered body 3a below the semiconductor element 2 has a recess 18 along the outer periphery of the semiconductor element 2. Furthermore, the outer periphery of the first metal sintered body 3a protrudes upwards. With this structure, the recess 18 can suppress the first metal sintered body 3a from spreading to the upper part of the semiconductor element 2 during sintering, thereby suppressing abnormal operation of the semiconductor device.

[0048] Furthermore, in the above description, this embodiment 5 is applied to embodiment 4, but it can also be applied to any of embodiments 1 to 3.

[0049] <Variation Example 1>

[0050] In embodiments 1 to 5, the main component of at least one of the first metal sintered body 3a and the second metal sintered body 3b may also be copper, and the main component of at least one of the first metal sintered body 3a to the fourth metal sintered body 3d may also be copper. Copper has high thermal conductivity and low electrical resistance, thus enabling the high-density semiconductor device. Furthermore, since the use of silver is suppressed, the formation of whiskers can be suppressed.

[0051] <Variation Example 2>

[0052] In embodiments 1 to 5, the material of semiconductor element 2 may also include a wide-bandgap semiconductor. Wide-bandgap semiconductors include, for example, silicon carbide (SiC), gallium nitride (GaN), and diamond. In a structure where the material of semiconductor element 2 includes silicon carbide, which is suitable for low-loss operation at high temperatures and high frequencies, the aforementioned high heat dissipation and low inductance are particularly effective, enabling the realization of high-quality and high-performance semiconductor devices.

[0053] <Variation Example 3>

[0054] In embodiments 1 to 5, the semiconductor element 2 may also include an RC-IGBT (reverse-conduction IGBT). In the structure where the semiconductor element 2 includes an RC-IGBT, the heat generation of the semiconductor element 2 increases; however, due to the aforementioned high heat dissipation and high reliability at high temperatures, the disadvantages caused by the heat generation of the semiconductor element 2 can be reduced. On the other hand, the advantage of high-density semiconductor devices brought about by using RC-IGBTs can be obtained.

[0055] Furthermore, it is possible to freely combine the various embodiments and variations, or to appropriately modify or omit the various embodiments and variations.

[0056] Explanation of the label

[0057] 1. Insulating layer; 2. Semiconductor element; 3a. First metal sintered body; 3b. Second metal sintered body; 3c. Third metal sintered body; 3d. Fourth metal sintered body; 4. Base plate; 5. Housing; 6. Adhesive; 17. Metal plate; 18. Recess.

Claims

1. A semiconductor device comprising: An insulating layer having a first surface and a second surface opposite to the first surface; There is one or more semiconductor elements located on the first surface side; A first metal sintered body is in contact with the first surface of the insulating layer and the semiconductor element, thereby bonding the insulating layer to the semiconductor element; A second sintered metal body is in contact with the second surface of the insulating layer; A housing that covers the semiconductor element; as well as A third sintered metal body is in contact with the first surface of the insulating layer, and an adhesive is provided between the third sintered metal body and the shell. The insulating layer is made of ceramic. The first, second, and third sintered metal bodies are obtained by curing a paste material in which metal particles are mixed with a solvent.

2. The semiconductor device according to claim 1, wherein, It also includes: a base plate that contacts the second metal sintered body and is bonded to the insulating layer through the second metal sintered body.

3. The semiconductor device according to claim 1 or 2, wherein, The term "one or more semiconductor elements" refers to multiple semiconductor elements. The semiconductor device further comprises: a metal plate located on the opposite side of the insulating layer relative to the plurality of semiconductor elements, and bonded to the plurality of semiconductor elements.

4. The semiconductor device according to claim 3, wherein, It also includes: a fourth metal sintered body that bonds the plurality of semiconductor elements to the metal plate, the fourth metal sintered body having the same material as the first metal sintered body and the second metal sintered body.

5. The semiconductor device according to claim 1 or 2, wherein, The thickness of the first metal sintered body is greater than or equal to 0.2 mm.

6. The semiconductor device according to claim 1 or 2, wherein, The thickness of the first sintered metal body is greater than the thickness of the second sintered metal body.

7. The semiconductor device according to claim 1 or 2, wherein, The first metal sintered body and the second metal sintered body have different thicknesses.

8. The semiconductor device according to claim 1 or 2, wherein, The first metal sintered body has a recess along the outer periphery of the semiconductor element.

9. The semiconductor device according to claim 1 or 2, wherein, The main component of at least one of the first metal sintered body and the second metal sintered body is copper.

10. The semiconductor device according to claim 1 or 2, wherein, The semiconductor element is made of a wide-bandgap semiconductor.

11. The semiconductor device according to claim 1 or 2, wherein, The semiconductor device includes an RC-IGBT.

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