JP2016046403A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology by which deformation of a semiconductor chip can be suppressed.SOLUTION: A semiconductor device 1 comprises: a semiconductor chip 10; an intermediate member 30 bonded to the semiconductor chip 10 via a first joint material 41; and a first metal plate 21 bonded to the intermediate member 30 via a second joint material 42. A coefficient of linear expansion of the intermediate member 30 is larger than that of the semiconductor chip 10 and is smaller than that of the first metal plate 21. A rigidity of the first joint material 41 is greater than that of the second joint material 42.SELECTED DRAWING: Figure 1

Description

  The technology disclosed in this specification relates to a semiconductor device.

  Patent Document 1 discloses a semiconductor device. The semiconductor device of Patent Document 1 includes a metal electrode plate, a metal part formed on the surface of the metal electrode plate, and a semiconductor chip fixed to the metal part via solder.

JP 2010-258015 A

  In the semiconductor device of Patent Document 1, the metal electrode plate and the metal part expand / contract due to a change in temperature. As a result, the semiconductor chip may be deformed. Therefore, an object of the present specification is to provide a technique capable of suppressing deformation of a semiconductor chip.

  The semiconductor device disclosed in this specification includes a semiconductor chip, an intermediate member bonded to the semiconductor chip via a first bonding material, a metal plate bonded to the intermediate member via a second bonding material, It has. A linear expansion coefficient of the intermediate member is larger than a linear expansion coefficient of the semiconductor chip and smaller than a linear expansion coefficient of the metal plate. The rigidity of the first bonding material is greater than or equal to the rigidity of the second bonding material.

  According to such a configuration, since the semiconductor chip and the intermediate member are bonded by the first bonding material, and the intermediate member and the first metal plate are bonded by the second bonding material, the expansion amount of the semiconductor chip and the first metal plate The influence of the difference between the first bonding material and the second bonding material is dispersed through an intermediate member having an expansion amount intermediate between the two expansion amounts, and the strain is dispersed. Moreover, since the rigidity of the 1st joining material which joins a semiconductor chip is more than the rigidity of a 2nd joining material, the restraining force by a 1st joining material becomes stronger than the restraining force by a 2nd joining material. Thereby, deformation of the semiconductor chip can be suppressed by the first bonding material.

It is sectional drawing of a semiconductor device. It is a figure explaining the manufacturing method of a semiconductor device (1). It is a figure explaining the manufacturing method of a semiconductor device (2). It is a figure explaining the manufacturing method of a semiconductor device (3). It is sectional drawing of the semiconductor device which concerns on other embodiment.

  Hereinafter, embodiments will be described with reference to the accompanying drawings. As shown in FIG. 1, the semiconductor device 1 according to the embodiment includes a semiconductor chip 10, an intermediate member 30 bonded to the semiconductor chip 10 via a first bonding material 41, and a second bonding material 42 to the intermediate member 30. The 1st metal plate 21 joined via this is provided. In addition, the semiconductor device 1 includes a spacer 23 bonded to the semiconductor chip 10 via the third bonding material 43 and a second metal plate 22 bonded to the spacer 23 via the third bonding material 43. . In addition, the semiconductor device 1 includes a sealing resin 60 that seals the whole.

  The semiconductor chip 10 is disposed between the first metal plate 21 and the second metal plate 22. The back surface 102 of the semiconductor chip 10 is fixed to the first metal plate 21 via the first bonding material 41, the intermediate member 30, and the second bonding material 42. The surface 101 of the semiconductor chip 10 is fixed to the second metal plate 22 via the third bonding material 43 and the spacer 23.

  The semiconductor chip 10 has a configuration in which a semiconductor element is formed inside a semiconductor substrate. For example, an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) can be used as the semiconductor chip 10. When the semiconductor chip 10 is, for example, an IGBT, a gate region, an emitter region, a collector region, and the like are formed inside the semiconductor substrate (not shown).

  As a material of a semiconductor substrate used for the semiconductor chip 10, for example, silicon (Si) or silicon carbide (SiC) can be used. In the present embodiment, silicon carbide (SiC) is used as the material of the semiconductor substrate. The Young's modulus of silicon (Si) is about 169 GPa. Moreover, the Young's modulus of silicon carbide (SiC) is about 450 GPa. Silicon (Si) has a linear expansion coefficient of about 3 ppm / ° C. Silicon carbide (SiC) has a linear expansion coefficient of about 5 ppm / ° C. The linear expansion coefficient of the semiconductor chip 10 is smaller than the linear expansion coefficients of the intermediate member 30, the first metal plate 21, and the second metal plate 22. The semiconductor chip 10 expands / contracts due to temperature changes. The semiconductor chip 10 expands when the temperature increases and contracts when the temperature decreases. The semiconductor chip 10 generates heat during operation.

  The intermediate member 30 is formed in a plate shape. The intermediate member 30 is disposed between the semiconductor chip 10 and the first metal plate 21. A surface 301 of the intermediate member 30 is fixed to the semiconductor chip 10 via the first bonding material 41. The back surface 302 of the intermediate member 30 is fixed to the first metal plate 21 via the second bonding material 42. When viewed in plan along the stacking direction of each member, the plane area of the intermediate member 30 is larger than the plane area of the semiconductor chip 10 and smaller than the plane area of the first metal plate 21. The end 303 of the intermediate member 30 is located outside the position of the end 103 of the semiconductor chip 10. The end part 303 of the intermediate member 30 is located inside the position of the end part 213 of the first metal plate 21.

  The intermediate member 30 is made of metal. The material of the intermediate member 30 is different from the material of the first metal plate 21 and the second metal plate 22. As a material of the intermediate member 30, for example, CuMo and 42 Alloy can be used. In this embodiment, CuMo is used as the material of the intermediate member 30. The Young's modulus of CuMo is about 280 GPa for 85Mo15Cu and about 170 GPa for 40Mo60Cu. The Young's modulus of 42 Alloy is about 150 GPa. The coefficient of linear expansion of CuMo is about 9 ppm / ° C. Moreover, the linear expansion coefficient of 42 Alloy is about 6 ppm / ° C. The linear expansion coefficient of the intermediate member 30 is larger than the linear expansion coefficient of the semiconductor chip 10. The linear expansion coefficient of the intermediate member 30 is smaller than the linear expansion coefficients of the first metal plate 21 and the second metal plate 22. The linear expansion coefficient of the intermediate member 30 is a value between the linear expansion coefficient of the semiconductor chip 10 and the linear expansion coefficient of the first metal plate 21. The intermediate member 30 expands / contracts due to temperature changes. The intermediate member 30 expands when the temperature increases and contracts when the temperature decreases.

  The first metal plate 21 is disposed below the intermediate member 30. The surface 211 of the first metal plate 21 is fixed to the intermediate member 30 via the second bonding material 42. The back surface 212 (the surface opposite to the second bonding material 42 side) of the first metal plate 21 is exposed from the sealing resin 60. The first cooler 71 is in contact with the back surface 212 of the first metal plate 21. When viewed in plan along the stacking direction of each member, the planar area of the first metal plate 21 is larger than the planar area of the semiconductor chip 10 and the planar area of the intermediate member 30. The end 213 of the first metal plate 21 is located outside the positions of the end 103 of the semiconductor chip 10 and the end 303 of the intermediate member 30.

  The second metal plate 22 is disposed above the spacer 23. A back surface 222 of the second metal plate 22 is fixed to the spacer 23 via a third bonding material 43. The surface 221 of the second metal plate 22 (the surface opposite to the third bonding material 43 side) is exposed from the sealing resin 60. A second cooler 72 is in contact with the surface 221 of the second metal plate 22. When viewed in plan, the plane area of the second metal plate 22 is larger than the plane area of the semiconductor chip 10 and the plane area of the intermediate member 30. The end 223 of the second metal plate 22 is located outside the end 103 of the semiconductor chip 10 and the end 303 of the intermediate member 30.

  As a material of the first metal plate 21 and the second metal plate 22, for example, copper (Cu) can use aluminum (Al). In the present embodiment, copper (Cu) is used as the material of the first metal plate 21 and the second metal plate 22. The Young's modulus of copper (Cu) is about 124 GPa. The Young's modulus of aluminum (Al) is about 70 GPa. Moreover, the linear expansion coefficient of copper (Cu) is about 17 ppm / ° C. The linear expansion coefficient of aluminum (Al) is about 23 ppm / ° C. The linear expansion coefficients of the first metal plate 21 and the second metal plate 22 are larger than the linear expansion coefficients of the semiconductor chip 10 and the intermediate member 30. The first metal plate 21 and the second metal plate 22 expand / contract due to temperature changes. The first metal plate 21 and the second metal plate 22 expand when the temperature increases, and contract when the temperature decreases.

  The first metal plate 21 and the second metal plate 22 have thermal conductivity and conductivity. The first metal plate 21 and the second metal plate 22 have a function of radiating heat generated in the semiconductor chip 10. Moreover, the 1st metal plate 21 and the 2nd metal plate 22 have a function as an electrode.

  The spacer 23 is disposed between the semiconductor chip 10 and the second metal plate 22. The back surface 232 of the spacer 23 is fixed to the semiconductor chip 10 via the third bonding material 43. The surface 231 of the spacer 23 is fixed to the second metal plate 22 via the third bonding material 43. The spacer 23 is formed in a plate shape. The spacer 23 is made of metal. As a material of the spacer 23, for example, copper (Cu) can be aluminum (Al).

  The first bonding material 41 is filled between the semiconductor chip 10 and the intermediate member 30. The first bonding material 41 joins the semiconductor chip 10 and the intermediate member 30. The first bonding material 41 is in close contact with the semiconductor chip 10 and the intermediate member 30. The plane area on the intermediate member 30 side of the first bonding material 41 is larger than the plane area on the semiconductor chip 10 side.

  The second bonding material 42 is filled between the intermediate member 30 and the first metal plate 21. The second bonding material 42 joins the intermediate member 30 and the first metal plate 21. The second bonding material 42 is in close contact with the intermediate member 30 and the first metal plate 21. The plane area on the first metal plate 21 side of the second bonding material 42 is larger than the plane area on the intermediate member 30 side.

  The third bonding material 43 is filled between the semiconductor chip 10 and the spacer 23 and between the spacer 23 and the second metal plate 22. The third bonding material 43 bonds the semiconductor chip 10 and the spacer 23, and the spacer 23 and the second metal plate 22. The third bonding material 43 is in close contact with the semiconductor chip 10, the spacer 23 and the second metal plate 22.

  As a material of the first bonding material 41, for example, a CuSn compound, a NiSn compound, an Ag sintered body, a Zn-based solder, or the like can be used. Cu3Sn, Cu6Sn5, etc. can be used as the CuSn compound. Ni3Sn4 or the like can be used as the NiSn compound. In the present embodiment, Ni 3 Sn 4 is used as the material of the first bonding material 41. The Young's modulus of Cu3Sn is about 108 GPa. The Young's modulus of Cu6Sn5 is about 86 GPa. The Young's modulus of Ni3Sn4 is about 133 GPa. The Young's modulus of the Ag sintered body is about 9 to 80 GPa.

  As the material of the second bonding material 42 and the third bonding material 43, for example, Sn solder, SnCu solder, Zn solder, or the like can be used. The Young's modulus of Sn-based solder is about 42 GPa. The Young's modulus of SnCu solder is about 50 GPa.

  The rigidity of the first bonding material 41 is greater than the rigidity of the second bonding material 42. The Young's modulus of the first bonding material 41 is larger than the Young's modulus of the second bonding material 42. When the same force is applied to the first bonding material 41 and the second bonding material 42, the displacement of the first bonding material 41 is smaller than the displacement of the second bonding material 42. That is, when the same force is applied to the first bonding material 41 and the second bonding material 42, the strain of the first bonding material 41 is smaller than the strain of the second bonding material 42. The Young's modulus of the first bonding material 41 and the second bonding material 42 is smaller than the Young's modulus of the semiconductor chip 10.

  The sealing resin 60 is filled between the first metal plate 21 and the second metal plate 22. The sealing resin 60 is a member between the first metal plate 21 and the second metal plate 22 (semiconductor chip 10, intermediate member 30, spacer 23, first bonding material 41, second bonding material 42, and third bonding material. 43) is sealed. The sealing resin 60 is in close contact with a member between the first metal plate 21 and the second metal plate 22. As a material of the sealing resin 60, an epoxy resin can be used as a main component. In addition, the sealing resin 60 may include a curing agent, a stress relaxation agent, a curing accelerator, a filler, and the like.

  The first cooler 71 is disposed below the first metal plate 21. The first cooler 71 cools the semiconductor chip 10 via the first metal plate 21. The second cooler 72 is disposed above the second metal plate 22. The second cooler 72 cools the semiconductor chip 10 via the second metal plate 22. As the first cooler 71 and the second cooler 72, for example, a water-cooled configuration can be used.

  Next, an example of a method for manufacturing the semiconductor device 1 will be described. When manufacturing the semiconductor device 1, first, the back surface 102 of the semiconductor chip 10 is metallized using nickel (Ni). Thereby, a Ni film is formed on the back surface 102 of the semiconductor chip 10. Further, the surface 301 of the intermediate member 30 is plated using nickel (Ni). Thereby, a Ni film is formed on the surface 301 of the intermediate member 30.

  Next, as shown in FIG. 2, an Sn-based solder paste 91 is disposed on the surface 301 of the intermediate member 30 on which the Ni film is formed, and the semiconductor chip 10 on which the Ni film is formed is disposed on the solder paste 91. In this state, the whole is heat-treated. As a result, the Ni film formed on the intermediate member 30 and the semiconductor chip 10 reacts with the Sn-based solder paste 91 to form the first bonding material 41 of the NiSn compound (Ni3Sn4). Further, the semiconductor chip 10 and the intermediate member 30 are bonded by the first bonding material 41.

  Next, as shown in FIG. 3, an Sn-based solder paste 91 is disposed on the first metal plate 21, and the intermediate member 30 to which the semiconductor chip 10 is bonded is disposed on the solder paste 91. An Sn-based solder paste 91 is disposed on the semiconductor chip 10, and the spacer 23 is disposed on the solder paste 91. Further, an Sn-based solder paste 91 is disposed on the spacer 23, and the second metal plate 22 is disposed on the solder paste 91. In this state, the whole is heat-treated. Thereby, the solder paste 91 is heated and the second bonding material 42 and the third bonding material 43 are formed. Further, the intermediate member 30 and the first metal plate 21 are joined by the second joining material 42. Further, the semiconductor chip 10 and the spacer 23, and the spacer 23 and the second metal plate 22 are bonded by the third bonding material 43. In addition, when performing soldering in the manufacturing method of the semiconductor device 1, preform solder may be used.

  Next, as shown in FIG. 4, what is joined in the above process is placed inside the mold 100, and a resin is injected into the mold 100. When the injected resin is cured, a sealing resin 60 is formed. The semiconductor device 1 is manufactured as described above.

  According to the semiconductor device 1 having the above configuration, when the semiconductor chip 10 is energized, the semiconductor chip 10 generates heat and the temperature of the semiconductor device 1 rises. If it does so, the temperature of the semiconductor chip 10, the intermediate member 30, and the 1st metal plate 21 will rise, and each will expand | swell. The semiconductor chip 10, the intermediate member 30, and the first metal plate 21 have different linear expansion coefficients and therefore have different expansion amounts. Due to the difference in expansion amount, the first bonding material between the semiconductor chip 10 and the intermediate member 30. 41 and the second bonding material 42 between the intermediate member 30 and the first metal plate 21 are distorted. At this time, the intermediate member 30 is disposed between the semiconductor chip 10 and the first metal plate 21, and the intermediate member 30 is bonded to the semiconductor chip 10 via the first bonding material 41, and via the second bonding material 42. Since the first metal plate 21 is bonded to the intermediate member 30, the strain can be distributed to the first bonding material 41 and the second bonding material 42. That is, if the intermediate member 30 is not disposed between the semiconductor chip 10 and the first metal plate 21 and the semiconductor chip 10 and the first metal plate 21 are bonded by one type of bonding material, the semiconductor chip 10 The difference in expansion amount between the first metal plate 21 and the first metal plate 21 all affect one type of bonding material, and the strain cannot be dispersed. However, according to the above configuration, the semiconductor chip 10 and the intermediate member 30 are bonded by the first bonding material 41, and the intermediate member 30 and the first metal plate 21 are bonded by the second bonding material 42. And the influence of the difference in expansion amount of the first metal plate 21 are dispersed in the first bonding material 41 and the second bonding material 42 via the intermediate member 30, and the strain is dispersed. Further, since the rigidity of the first bonding material 41 for bonding the semiconductor chip 10 is larger than the rigidity of the second bonding material 42, the restraining force by the first bonding material 41 is stronger than the restraining force by the second bonding material 42. Thereby, the deformation | transformation of the semiconductor chip 10 can be suppressed by the 1st joining material 41, and the lifetime of the semiconductor device 1 can be improved. Further, since the restraining force by the second bonding material 42 is weaker than the restraining force by the first bonding material 41, the second bonding material 42 can follow the expansion of the first metal plate 21. Thereby, the crack of the 2nd joining material 42 can be suppressed and the lifetime of the semiconductor device 1 can be improved.

  Further, since the Young's modulus of the first bonding material 41 is smaller than the Young's modulus of the semiconductor chip 10, the first bonding material 41 is more easily deformed than the semiconductor chip 10, and the semiconductor chip 10 is excessively restrained by the first bonding material 41. There is nothing to do. Thereby, the semiconductor chip 10 can be held moderately and damage to the semiconductor chip 10 can be suppressed. Further, since the plane area of the intermediate member 30 is larger than the plane area of the semiconductor chip 10, the bonding area of the first bonding material 41 can be increased. Thereby, the semiconductor chip 10 can be reliably joined to the intermediate member 30, and the lifetime of the semiconductor device 1 can be increased.

  As mentioned above, although one embodiment was described, a specific mode is not limited to the above-mentioned embodiment. For example, in another embodiment, as shown in FIG. 5, a plurality of through holes 36 may be formed in the intermediate member 30. In FIG. 5, the same components as those in FIG. Each through hole 36 penetrates the intermediate member 30 in the thickness direction. The through hole 36 extends along the direction from the first metal plate 21 toward the semiconductor chip 10. The through hole 36 is located below the semiconductor chip 10. The plurality of through holes 36 are formed at positions inside the position of the end portion 103 of the semiconductor chip 10. In another example, the plurality of through holes 36 may be formed at both an inner position and an outer position than the position of the end portion 103 of the semiconductor chip 10. The through hole 36 is filled with the second bonding material 42. The second bonding material 42 filled in the through hole 36 is in close contact with the first bonding material 41. According to such a configuration, since the through hole 36 is formed in the intermediate member 30, the intermediate member 30 is easily deformed, and the strain of the second bonding material 42 can be reduced. The number of through holes 36 formed in the intermediate member 30 is not particularly limited, and at least one through hole 36 may be formed in the intermediate member 30.

  Moreover, in the said embodiment, although the plane area of the intermediate member 30 in planar view was larger than the plane area of the semiconductor chip 10, it is not limited to this structure. In another embodiment, the plane area of the intermediate member 30 in plan view may be the same size as the plane area of the semiconductor chip 10.

  Moreover, in the said embodiment, although the rigidity of the 1st joining material 41 was a structure larger than the rigidity of the 2nd joining material 42, it is not limited to this structure. In other embodiments, the rigidity of the first bonding material 41 may be the same as the rigidity of the second bonding material 42. In the above embodiment, the Young's modulus of the first bonding material 41 is larger than the Young's modulus of the second bonding material 42. In other embodiments, the Young's modulus of the first bonding material 41 is 2 It may be the same as the Young's modulus of the bonding material 42. In this case, the material of the 1st joining material 41 and the material of the 2nd joining material 42 can use the same material.

  The technical elements of the semiconductor device disclosed in this specification will be described below. Note that the technical elements described below are independent technical elements, and exhibit technical usefulness alone or in various combinations.

  In the semiconductor device disclosed in this specification as an example, the rigidity of the first bonding material may be greater than or equal to the rigidity of the second bonding material.

  In the semiconductor device disclosed in this specification as an example, the Young's modulus of the first bonding material may be greater than or equal to the Young's modulus of the second bonding material.

  In the semiconductor device disclosed in this specification as an example, at least one through hole extending along a direction from the metal plate toward the semiconductor chip is formed in the intermediate member at a position inside the position of the end portion of the semiconductor chip. May be.

  In the semiconductor device disclosed in this specification as an example, the Young's modulus of the first bonding material may be smaller than the Young's modulus of the semiconductor chip. The plane area of the intermediate member may be larger than the plane area of the semiconductor chip.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

1: Semiconductor device 10: Semiconductor chip 21: 1st metal plate 22: 2nd metal plate 23: Spacer 30: Intermediate member 36: Through hole 41: 1st joining material 42: 2nd joining material 43: 3rd joining material 60 : Sealing resin 71: First cooler 72: Second cooler 91: Solder paste 100: Mold

Claims (4)

A semiconductor chip;
An intermediate member bonded to the semiconductor chip via a first bonding material;
A metal plate joined to the intermediate member via a second joining material,
The linear expansion coefficient of the intermediate member is larger than the linear expansion coefficient of the semiconductor chip and smaller than the linear expansion coefficient of the metal plate;
A semiconductor device, wherein the rigidity of the first bonding material is equal to or higher than the rigidity of the second bonding material.   The semiconductor device according to claim 1, wherein a Young's modulus of the first bonding material is equal to or greater than a Young's modulus of the second bonding material.   3. The semiconductor device according to claim 1, wherein at least one through hole extending in a direction from the metal plate toward the semiconductor chip is formed in the intermediate member.   The semiconductor device according to claim 1, wherein a Young's modulus of the first bonding material is smaller than a Young's modulus of the semiconductor chip.

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