Semiconductor equipment

Abstract

To provide a technique of suppressing the reaction of a thermal conductive material accommodated in a sealed space with moisture.SOLUTION: A semiconductor device 1 includes substrates 10 and 20, a semiconductor chip 30 provided on the substrate, a heat sink 50 facing the semiconductor chip, a thermal conductive material 40 of liquid metal provided between the semiconductor chip and the heat sink, a sealing material 60 that is provided apart from the semiconductor chip, surrounds the semiconductor chip, and defines a sealing space 80 between the substrate and the heat sink, and a moisture barrier material 70 provided in at least a part of the sealing space between the semiconductor chip and the sealing material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The technology disclosed in this specification relates to semiconductor devices.

[0002] Patent Document 1 discloses a semiconductor device including a substrate, a semiconductor chip provided on the substrate, a heat sink facing the semiconductor chip, and a liquid metal thermal conductive material provided between the semiconductor chip and the heat sink. This semiconductor device further includes a sealing material provided away from the semiconductor chip and surrounding the periphery of the semiconductor chip, which defines a sealed space between the substrate and the heat sink.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In such a semiconductor device, for example, there is a concern that moisture may enter the sealed space through the sealing material in a high-humidity environment. When the moisture that has entered the sealed space touches the liquid metal thermal conductive material, the thermal conductive material reacts with the moisture and the thermal conductive material deteriorates. This specification provides a technology for suppressing the reaction of the thermal conductive material accommodated in the sealed space with moisture.

Means for Solving the Problems

[0005] A semiconductor device disclosed herein may include a substrate (10, 20), a semiconductor chip (30) provided on the substrate, a heat sink (50) facing the semiconductor chip, a liquid metal thermal conductive material (40) provided between the semiconductor chip and the heat sink, a sealing material (60) provided away from the semiconductor chip and surrounding the semiconductor chip, defining a sealing space (80) between the substrate and the heat sink, and a moisture barrier material (70) provided between the semiconductor chip and the sealing material and in at least a portion of the sealing space.

[0006] In the semiconductor device described above, the moisture barrier material is provided between the thermal conductive material and the sealing material. Therefore, even if moisture penetrates the sealed space through the sealing material, it is suppressed that the penetrated moisture passes through the moisture barrier material and reaches the thermal conductive material. In the semiconductor device described above, the reaction of the thermal conductive material contained within the sealed space with moisture is suppressed. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram schematically shows a cross-sectional view of the main components of a semiconductor device. [Figure 2] This figure schematically shows a plan view of the semiconductor device shown in Figure 1, with the heat sink removed. [Figure 3] This figure shows a modified version of the semiconductor device shown in Figure 1, schematically illustrating a plan view of the semiconductor device with the heat sink removed. [Figure 4] This figure shows a modified version of the semiconductor device shown in Figure 1, schematically illustrating a plan view of the semiconductor device with the heat sink removed. [Figure 5] This is a modified example of the semiconductor device shown in Figure 1, and schematically shows a cross-sectional view of the main part of the semiconductor device. [Modes for carrying out the invention]

[0008] As shown in Figures 1 and 2, the semiconductor device 1 comprises a circuit board 10, an interposer 20, a semiconductor chip 30, a thermal conductive material 40, a heat sink 50, a sealing material 60, and a moisture barrier material 70. The circuit board 10, interposer 20, semiconductor chip 30, thermal conductive material 40, and heat sink 50 are stacked in this order. In this specification, the circuit board 10 and interposer 20 together are referred to as the substrate.

[0009] The semiconductor chip 30 is not particularly limited, but may be, for example, an integrated circuit for controlling various devices mounted in a vehicle. The semiconductor chip 30 is mounted on the circuit board 10 via the interposer 20 and is electrically connected to the circuit board 10 via the interposer 20. Thus, the semiconductor chip 30 is provided on a substrate consisting of the circuit board 10 and the interposer 20.

[0010] The thermal conductive material 40 is placed between the semiconductor chip 30 and the heat sink 50 and is in contact with both the semiconductor chip 30 and the heat sink 50. The thermal conductive material 40 plays the role of dissipating the heat generated by the semiconductor chip 30 to the heat sink 50. The thermal conductive material 40 is made of a material that has a melting point of 100°C or less and is fluid at least when the semiconductor chip 30 is operating. The thermal conductive material 40 may or may not be fluid at room temperature (e.g., 20°C). The thermal conductive material 40 is not particularly limited, but may be a liquid metal mainly composed of gallium (Ga), for example. Specifically, the thermal conductive material 40 may be Ga, GaInSn, for example. Note that a liquid metal mainly composed of gallium (Ga) is fluid at room temperature (e.g., 20°C). When such a liquid metal is used as the thermal conductive material 40, both the interfacial thermal resistance between the thermal conductive material 40 and the semiconductor chip 30, and the interfacial thermal resistance between the thermal conductive material 40 and the heat sink 50 are kept low. Furthermore, since the thermal conductive material 40 contains metal, it has high thermal conductivity. Therefore, the semiconductor device 1 can have high heat dissipation performance.

[0011] The heat sink 50 is made of a plate-shaped metal material, and is not particularly limited, but is made of a metal material with high thermal conductivity such as copper or aluminum. The heat sink 50 extends further laterally than shown in the figure and is connected to the fins at its lateral portion.

[0012] The sealing material 60 is positioned away from the semiconductor chip 30 and surrounds the semiconductor chip 30 in a circular fashion. The sealing material 60 is positioned between the interposer 20 and the heat sink 50 and is in contact with both the interposer 20 and the heat sink 50. In this way, the sealing material 60 defines a sealed space 80 between the interposer 20 and the heat sink 50. The sealing material 60 prevents the liquid metal contained within the sealed space 80 from leaking out. The sealing material 60 is not particularly limited, but may be made of, for example, resin.

[0013] The moisture barrier material 70 is located within the sealing space 80 and is provided between the semiconductor chip 30 and the sealing material 60. The moisture barrier material 70 is located away from the semiconductor chip 30 and surrounds the semiconductor chip 30. In this example, the moisture barrier material 70 is adjacent to the sealing material 60 and surrounds the semiconductor chip 30 in a circular fashion along the inner surface of the sealing material 60. Various materials capable of suppressing moisture movement more effectively than the sealing material 60 can be used for the moisture barrier material 70. The moisture barrier material 70 is not particularly limited, but may, for example, be a liquid metal mainly composed of gallium (Ga). Specifically, the moisture barrier material 70 may be, for example, Ga or GaInSn. Thus, the moisture barrier material 70 may be a liquid metal of the same material as the thermal conductive material 40. Alternatively, the moisture barrier material 70 may be an adsorbent that adsorbs moisture.

[0014] For example, in a high-humidity environment, moisture may penetrate into the sealed space 80 through the sealant 60. If the moisture barrier material 70 is not provided, the moisture that has penetrated into the sealed space 80 will come into contact with the liquid metal thermal conductive material 40 and react with the thermal conductive material 40. For example, if the thermal conductive material 40 is made of a liquid metal consisting of Ga, then, as shown in the following reaction equation, gallium oxide (Ga2O3) and hydrogen (H2) will be produced by the reaction between the thermal conductive material 40 and moisture. Note that metal oxides and hydrogen may be produced similarly even with other types of liquid metals. 2Ga + 3H2O → Ga2O3 + 3H2

[0015] Gallium oxide is a solid. Therefore, a portion of the liquid metal thermal conductive material 40 changes to a solid, worsening the contact between the thermal conductive material 40 and the semiconductor chip 30 and between the thermal conductive material 40 and the heat sink 50, increasing the thermal resistance between the semiconductor chip 30 and the heat sink 50. In addition, hydrogen is generated, causing a portion of the thermal conductive material 40 to leak out from between the semiconductor chip 30 and the heat sink 50, forming a gap between the semiconductor chip 30 and the heat sink 50, and increasing the thermal resistance between the semiconductor chip 30 and the heat sink 50. Thus, if the moisture barrier material 70 is not provided, the reaction between moisture that has entered the sealed space 80 and the thermal conductive material 40 increases the thermal resistance between the semiconductor chip 30 and the heat sink 50.

[0016] On the other hand, in semiconductor device 1, a moisture barrier material 70, which is a liquid metal, is provided between the thermal conductive material 40 and the sealing material 60. Therefore, even if moisture penetrates into the sealed space 80 through the sealing material 60, the moisture reacts with the moisture barrier material 70, preventing the moisture from moving further inside the sealed space 80 beyond the moisture barrier material 70. In this way, the moisture barrier material 70 suppresses the movement of the penetrated moisture, thereby suppressing the reaction between the thermal conductive material 40 and the moisture. In semiconductor device 1, the increase in thermal resistance between the semiconductor chip 30 and the heat sink 50 due to the reaction between the thermal conductive material 40 and moisture is suppressed, so semiconductor device 1 can maintain its heat dissipation performance. Semiconductor device 1 can have long-term reliability.

[0017] As shown in Figure 2, in the semiconductor device 1, the moisture barrier material 70 is provided so as to encircle the semiconductor chip 30. This allows the moisture barrier material 70 to suppress the movement of moisture that has entered from any position in the sealing material 60 to the thermal conductive material 40, thereby effectively suppressing the reaction between the thermal conductive material 40 and moisture. Note that, as shown in Figure 3, a portion of the moisture barrier material 70 may be interrupted. In this case as well, the same effects as described above can be obtained. Furthermore, in the semiconductor device 1, the moisture barrier material 70 is positioned away from the thermal conductive material 40, and an air layer is interposed between the thermal conductive material 40 and the moisture barrier material 70. This prevents the reaction of the moisture barrier material 70 with moisture from affecting the thermal conductive material 40. Note that, as shown in Figure 4, a connection region 72 made of liquid metal of the same material as the thermal conductive material 40 may be provided in a portion between the thermal conductive material 40 and the moisture barrier material 70. In this case as well, the same effects as described above can be obtained. Note that a sponge material may be provided in the sealing space 80 between the thermal conductive material 40 and the moisture barrier material 70. Since moisture that has entered the sealed space 80 is further prevented from reaching the thermal conductive material 40, the reaction between the thermal conductive material 40 and moisture is more effectively suppressed.

[0018] Figure 5 shows a modified example of the semiconductor device 1. In the modified semiconductor device 1, a first through-hole 52 and a second through-hole 54 are formed in the heat sink 50. The first through-hole 52 is formed to communicate with the area where the thermal conductive material 40 is located and is sealed by a first cap 92. The second through-hole 54 is formed to communicate with the area where the moisture barrier material 70 is located and is sealed by a second cap 94. The caps 92 and 94 are not particularly limited, but may be made of resin, for example. In addition, in the modified semiconductor device 1, a recess 56 is formed on the lower surface of the heat sink 50 corresponding to the area where the thermal conductive material 40 is located. When viewed from above, the recess 56 of the heat sink 50 is formed in an area inside the semiconductor chip 30. The thermal conductive material 40 is arranged to fit into the recess 56 of the heat sink 50.

[0019] These through-holes 52 and 54 are used to inject liquid metal into the sealing space 80. For example, the second through-hole 54 may be a through-hole for injecting liquid metal, and the first through-hole 52 may be a through-hole for venting when injecting liquid metal.

[0020] The semiconductor device 1 of the modified example may be manufactured, for example, in the following procedure. First, the semiconductor chip 30 is mounted on the circuit board 10 via the interposer 20. Next, a sealing material 60 is applied on the interposer 20 and around the semiconductor chip 30. Next, the heat sink 50 is assembled so as to face the semiconductor chip 30. Next, the interposer 20 and the heat sink 50 are adhered by curing the sealing material 60.

[0021] Next, liquid metal is injected into the sealing space 80 through the second through-hole 54. The injected liquid metal is filled between the semiconductor chip 30 and the sealing material 60 to form the moisture barrier material 70. When the injection of the liquid metal is continued, the liquid metal flows into the recess 56 of the heat sink 50 beyond the gap between the semiconductor chip 30 and the heat sink 50 (that is, the portion around the recess 56 of the heat sink 50 where the distance between the semiconductor chip 30 and the heat sink 50 is narrow). The liquid metal that has flowed into the recess 56 of the heat sink 50 is filled in the recess 56 to form the heat conductive material 40. Note that the surface tension of the liquid metal is large and the wettability is poor. Therefore, the liquid metal cannot remain in the gap between the semiconductor chip 30 and the heat sink 50, and the heat conductive material 40 and the moisture barrier material 70 are arranged separately. Finally, the through-holes 52 and 54 are sealed with caps 92 and 94, whereby the semiconductor device 1 of the modified example is completed. Thus, the semiconductor device 1 of the modified example in which the through-holes 52 and 54 are formed in the heat sink 50 has a structure suitable for manufacturing.

[0022] In the above example, one first through-hole 52 and one second through-hole 54 were formed in the heat sink 50. Instead of this example, a plurality of first through-holes 52 communicating with the range where the heat conductive material 40 exists may be formed, and a plurality of second through-holes 54 communicating with the range where the moisture barrier material 70 exists may be formed. Each of the set of the plurality of first through-holes 52 and the set of the plurality of second through-holes 54 has a through-hole for injecting liquid metal and a through-hole for venting. In this example, the heat conductive material 40 and the moisture barrier material 70 can be formed separately.

[0023] Hereinafter, the features of the technology disclosed in this specification will be sorted out. Note that the technical elements described below are each independent technical elements, which exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

[0024] (Feature 1) A substrate (10, 20), A semiconductor chip (30) provided on the substrate, A heat sink (50) facing the semiconductor chip, A heat conductive material (40) of liquid metal provided between the semiconductor chip and the heat sink, A sealing material (60) provided away from the semiconductor chip and surrounding the periphery of the semiconductor chip, and defining a sealed space (80) between the substrate and the heat sink, A semiconductor device comprising a moisture barrier material (70) provided between the semiconductor chip and the sealing material and at least partially within the sealed space.

[0025] (Feature 2) The semiconductor device according to Feature 1, wherein the heat conductive material is Ga or GaInSn.

[0026] (Feature 3) The semiconductor device according to Feature 1 or 2, wherein the moisture barrier material is provided away from the semiconductor chip and surrounds at least a part of the periphery of the semiconductor chip.

[0027] (Feature 4) The semiconductor device according to feature 3, wherein the moisture barrier material is provided so as to encircle the semiconductor chip.

[0028] (Feature 5) The semiconductor device according to feature 3 or 4, further comprising a sponge material provided between the semiconductor chip and the moisture barrier material in at least part of the space.

[0029] (Feature 6) The semiconductor device according to any one of features 1 to 5, wherein the moisture barrier material is a liquid metal.

[0030] (Feature 7) The semiconductor device according to feature 6, wherein the moisture barrier material is a liquid metal, Ga, or GaInSn.

[0031] (Feature 8) The heat sink has through holes that communicate with the sealing space. The semiconductor device according to feature 6 or 7, wherein the through-hole is sealed by a cap.

[0032] (Feature 9) The semiconductor device according to feature 8, wherein the through-hole has a first through-hole communicating with the area where the heat conductive material is present and a second through-hole communicating with the area where the moisture barrier material is present.

[0033] (Feature 10) The first through-hole has a plurality of through-holes, The semiconductor device according to feature 9, wherein the second through-hole has a plurality of through-holes.

[0034] Although embodiments have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings achieve multiple objectives simultaneously, and achieving even one of these objectives constitutes technical usefulness. [Explanation of Symbols]

[0035] 1: Semiconductor device, 10: Circuit board, 20: Interposer, 30: Semiconductor chip, 40: Thermal conductive material, 50: Heat sink, 60: Sealing material, 70: Moisture barrier material, 80: Sealing space

Claims

1. The substrate (10, 20) and A semiconductor chip (30) provided on the substrate, A heat sink (50) facing the semiconductor chip, A liquid metal thermal conductive material (40) is provided between the semiconductor chip and the heat sink, A sealing material (60) is provided separately from the semiconductor chip and surrounds the semiconductor chip, defining a sealing space (80) between the substrate and the heat sink, The system comprises a moisture barrier material (70) provided between the semiconductor chip and the sealing material, and in at least a portion of the sealing space, A semiconductor device in which the moisture barrier material is a liquid metal.

2. The semiconductor device according to claim 1, wherein the thermal conductive material is Ga or GaInSn.

3. The semiconductor device according to claim 1, wherein the moisture barrier material is provided away from the semiconductor chip and surrounds at least a portion of the area surrounding the semiconductor chip.

4. The semiconductor device according to claim 3, wherein the moisture barrier material is provided so as to encircle the semiconductor chip.

5. The semiconductor device according to claim 3, further comprising a sponge material provided between the semiconductor chip and the moisture barrier material in at least a portion thereof.

6. The semiconductor device according to claim 1, wherein the moisture barrier material is Ga or GaInSn.

7. The heat sink has through holes that communicate with the sealing space. The semiconductor device according to any one of claims 1 to 6, wherein the through hole is sealed by a cap.

8. The semiconductor device according to claim 7, wherein the through-hole has a first through-hole communicating with the area where the heat conductive material is present and a second through-hole communicating with the area where the moisture barrier material is present.

9. The first through-hole has a plurality of through-holes, The semiconductor device according to claim 8, wherein the second through-hole has a plurality of through-holes.

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