JPH11243168A - heatsink - Google Patents

Abstract

[PROBLEMS] To provide a heat sink capable of effectively exhibiting heat radiation characteristics and thermal expansion characteristics even when a semiconductor element having a large amount of heat is mounted on a surface thereof. The heat sink has a thickness of 200 μm to 600 μm.
And a substrate base material made of a non-metallic inorganic material. Further, the thickness formed on at least one surface of the substrate base material is 5 μm or more.
A polycrystalline diamond layer of 60 μm is provided. Further, Ti, Z is formed in a predetermined region on the surface of the polycrystalline diamond layer.
1 μm to 4 μm thick composed of at least one selected from oxides, carbides, nitrides and carbonitrides of r, Hf, Nb, Ta, Cr, Mo, W, Au, Ni and V
μm of the first intermediate bonding layer. Further, a thickness of 2 μm to 5 μm formed on the first intermediate bonding layer and made of at least one selected from Mo, Ni, Pd, Pt, and Au.
m of the second intermediate bonding layer. Further, Au, Ag, Si, Ge, Sn, Pd and I are formed on the surface of the second intermediate bonding layer and the semiconductor element is mounted on the surface.
and a metal bonding layer made of at least one metal selected from n and having a thickness of 2 μm to 5 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink, and more particularly, to a heat sink having a semiconductor element having a large amount of heat generated thereon.

[0002]

2. Description of the Related Art A conventional electronic component on which a semiconductor element such as an LSI package is mounted does not generate much heat, and a heat sink having a thermal conductivity of about 17 W / m · K, such as Al ₂ O ₃ , is frequently used. I was However, in recent years, an increase in the amount of heat generated has become a problem due to higher performance and higher density mounting of LSIs. As a countermeasure, a material having excellent heat conduction properties such as AlN, SiC or Cu-W sintered body has been used. There is a strong tendency to use it as a heat sink (radiator substrate). Further, recently, a high-performance heat sink is used for a semiconductor element that generates a large amount of heat locally such as a laser diode (LD) as information density increases.

[0003] For example, the applicant of the present application is disclosed in Japanese Patent Laid-Open No. 5-326.
Japanese Patent Application Publication No. 767, “radiation board” proposes a heat sink as shown in FIG. The problem of the conventional heat sink will be described with reference to FIG.

FIG. 7 shows a state in which a semiconductor element 15, a bonding wire 17 connected to the semiconductor element 15, and a lead frame 16 connected to the bonding wire 17 are provided in the package 11. Then, under the semiconductor element 15, in order from the bottom, a substrate base material 12 made of metal or ceramic, a polycrystalline diamond layer 13, a first intermediate bonding layer 18a, and a second intermediate bonding layer 18
b, a heat dissipation board composed of the metal bonding layer 14 is provided. According to this, the heat generated by the use of a heat dissipation substrate having good heat conduction characteristics was dispersed.

[0005]

However, when ceramics having good thermal conductivity are selected as the substrate base material 12, for example, if Si is used, its coefficient of thermal expansion is from room temperature to 400 ° C.
3.5 for a × 10 ^-6 / ° C., in order to the thermal expansion coefficient of the entire 4.0 × 10 ^-6 / ℃ or higher by increasing the thickness of the bonding layer in the polycrystalline diamond layer 13 , And the thickness of the substrate base material 12 must be reduced. Also, A
4.3 × 10 ^-6 / ° C for 1N, 4.2 × 10 for SiC
^-6 / ° C., the thickness of the polycrystalline diamond layer 13 should be thinner than the substrate base material 12 in order to make the overall thermal expansion coefficient of 4.0 × 10 ⁻⁶ / ° C. or more as in the case of Si. Or conversely, the thickness of the polycrystalline diamond layer 13 is
In order to reduce the thickness to 0 μm to 50 μm, it is necessary to increase the thickness of the substrate base material. If the thickness of the polycrystalline diamond layer 13 is too small, or if the thickness of the substrate base material 12 is too large, it is contrary to the original intention of improving the thermal conductivity. Therefore, when used for a semiconductor device 15 such as an LD having a high output such as GaAs or InP, the stress inside the LD is applied when the temperature rises due to the difference in the coefficient of thermal expansion between the heat sink and the LD. There has been a problem that the LD is cracked.

[0006] The present invention relates to GaAs or In as described above.
The purpose of the present invention is to solve a problem that occurs when the semiconductor device 15 having a large calorific value such as an LD of P is used.
The purpose is not only to have a coefficient of thermal expansion corresponding to the type of the semiconductor element 15 so that the characteristics of the semiconductor element 15 such as the LD can be maintained even when the temperature rises, as well as to have excellent heat radiation characteristics and to improve the bonding strength. Is also to provide an excellent heat sink.

[0007]

According to a first aspect of the present invention, there is provided a heat sink having a base material made of a non-metallic inorganic material having upper and lower main surfaces and having a thickness between the upper and lower main surfaces of 200 μm to 600 μm. Prepare. In addition, the thickness formed on at least one of the upper and lower main surfaces of the substrate base material is 5 μm to 60 μm.
m with a polycrystalline diamond layer. Then, a semiconductor element is provided on the surface of the polycrystalline diamond layer.

With this configuration, the thickness of the substrate base material is 200 μm or more, and the strength is secured. Further, since the thickness of the substrate base material is 600 μm or less, heat radiation characteristics are also ensured. As a result, it is possible to provide a heat sink that can withstand use in terms of strength and operate the semiconductor element satisfactorily in terms of heat radiation characteristics even when an LD or the like whose temperature rises significantly is used.

A heat sink according to a second aspect is the heat sink according to the first aspect, wherein the polycrystalline diamond layer is provided on both the upper and lower main surfaces of the substrate base material.

With this configuration, the heat sink according to the first aspect further has one more layer and a diamond layer on two opposing surfaces of the substrate base material. Therefore, when there is a difference in elongation due to a difference in the coefficient of thermal expansion as compared with the case where only one of the layers has a polycrystalline diamond layer, the stress generated due to the difference in elongation in the plane direction due to the thermal expansion on the two surfaces is reduced Absorb. Thereby, the warpage of the heat sink is less likely to occur than when the polycrystalline diamond layer is provided only on one surface. As a result, it is possible to provide a heat sink that does not easily adversely affect the semiconductor element such as a crack.

A heat sink according to a third aspect is the heat sink according to the first or second aspect, wherein the heat sink is formed in a predetermined region on the surface of the polycrystalline diamond layer, and wherein Au, A
g, Si, Ge, Sn, Pd, and at least one metal selected from the group consisting of In and having a thickness of 2 μm to 5 μm.
A metal bonding layer.

With this configuration, the thickness of the metal bonding layer is defined in the range of 2 μm to 5 μm. Thereby, the difference in the coefficient of thermal expansion between the substrate and the semiconductor element can be set within an allowable range. Therefore, generation of stress due to a difference in the coefficient of thermal expansion can be reduced. As a result, it is possible to provide a heat sink in which the stress generated due to the difference in elongation due to the difference in the coefficient of thermal expansion between the semiconductor element and the polycrystalline diamond layer is within an allowable range.

A heat sink according to a fourth aspect is the heat sink according to the first or second aspect, wherein the heat sink is formed in a predetermined region on the surface of the polycrystalline diamond layer, and the Ti, Z
At least one selected from oxides, carbides, nitrides and carbonitrides of at least one substance selected from the group consisting of r, Hf, Nb, Ta, Cr, Mo, W, Au, Ni and V A first intermediate bonding layer having a thickness of 1 μm to 4 μm of various types is provided. The semiconductor device further includes a second intermediate bonding layer formed on the first intermediate bonding layer and made of at least one material selected from the group consisting of Mo, Ni, Pd, Pt, and Au and having a thickness of 2 μm to 5 μm. Furthermore, it is formed of at least one metal selected from the group consisting of Au, Ag, Si, Ge, Sn, Pd, and In, which is formed on the surface of the second intermediate bonding layer and on which the semiconductor element is mounted. Thickness 2
It has a metal bonding layer of μm to 5 μm.

With this configuration, the bonding strength between the crystalline diamond layer and the metal bonding layer can be increased. Therefore, the stress generated by the thermal expansion can be absorbed without causing a crack or the like in the metal bonding layer. As a result, even if there is a difference in the coefficient of thermal expansion, the heat sink that absorbs the stress generated due to the difference in elongation caused by the thermal expansion and has a low possibility of generating a crack or the like that can release the heat generated by the semiconductor element. Can be provided.

A heat sink according to a fifth aspect is the heat sink according to the first to fourth aspects, wherein the substrate base material is S
i, AlN, SiC, Si ₃ N ₄ or Si, AlN,
It is formed of a non-metallic sintered body selected from the group consisting of SiC and Si ₃ N ₄ .

With this configuration, Si, A
1N, SiC, Si ₃ N ₄ or Si, AlN, Si
Since the non-metallic sintered body selected from the group consisting of C and Si ₃ N ₄ has a high thermal conductivity, the heat radiation characteristics are improved. Further, it takes a value close to the coefficient of thermal expansion of the substrate base material and the semiconductor element. Therefore, the heat sink effectively absorbs the generated heat, and
It becomes difficult to deform asymmetrically with respect to the joining surface. As a result, it is possible to provide a heat sink whose thermal expansion characteristics are close to those of the semiconductor element and which have excellent heat absorption characteristics.

A heat sink according to a sixth aspect is the heat sink according to any one of the first to fifth aspects, wherein the polycrystalline diamond layer has a thermal conductivity of 500 W / m in a range of room temperature to 400 ° C. It is a predetermined value within the range of K to 2000 W / mK.

With this configuration, the heat radiation characteristics of the heat sink are improved. Therefore, heat generated by the semiconductor element can be effectively released. As a result, it is possible to provide a heat sink that does not adversely affect the semiconductor element such as cracks due to heat.

A heat sink according to a seventh aspect is the heat sink according to any one of the first to sixth aspects, wherein the heat sink has a convex bending on the semiconductor element side and a radius of curvature of 2.5 m or more at an arbitrary portion. It is.

With this configuration, when the polycrystalline diamond layer is on one side, the polycrystalline diamond layer expands due to heat more than the elongation of the substrate. Absorbs the deflection. Therefore, the heat sink is less likely to generate internal stress. As a result, a heat sink that does not adversely affect the semiconductor element can be provided.

The heat sink according to claim 8 is the heat sink according to any one of claims 1 to 7, wherein the material and thickness of the polycrystalline diamond layer and the base material of the substrate are set to predetermined materials and thicknesses, respectively. By doing so, the coefficient of thermal expansion in the in-plane direction of the main surface of the polycrystalline diamond layer is from room temperature to 4
It is set to a predetermined value within the range of 2.3 × 10 ^{−6 to} 4.0 × 10 ⁻⁶ / ° C. in the range of 00 ° C.

By doing so, the heat sink can tolerate a difference in elongation due to a difference in thermal expansion coefficient between the constituent materials of the polycrystalline diamond layer, the metal bonding layer, the first intermediate bonding layer and the second intermediate bonding layer. And heat dissipation characteristics can be secured. Therefore, the semiconductor element is less susceptible to adverse effects such as cracks due to heat generation. As a result, it is possible to provide a heat sink that can absorb heat generated by the semiconductor element and withstand thermal expansion.

A heat sink according to a ninth aspect is the heat sink according to any one of the first to eighth aspects, wherein the polycrystalline diamond layer is formed by a vapor phase synthesis method. By forming the polycrystalline diamond layer on the substrate by the vapor phase synthesis method, a polycrystalline diamond layer having a thickness of 5 μm to 60 μm can be easily formed. Therefore, it is possible to obtain a polycrystalline diamond layer having effective values of heat radiation characteristics and thermal expansion characteristics. As a result, it is possible to provide a heat sink applicable to thermal expansion and heat radiation of the semiconductor element.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 A heat sink according to Embodiment 1 will be described with reference to FIGS. As shown in FIG. 1, the heat sink according to the present embodiment includes a semiconductor element 5, a bonding wire 7 connected to the semiconductor element 5, and a lead frame 6 connected to the bonding wire 7 in a package 1. ing. Then, a ceramic substrate base material 2, a polycrystalline diamond layer 3, a first intermediate bonding layer 8a, a second intermediate bonding layer 8b, and a metal bonding layer 4 are provided in this order from the bottom to form a base of the semiconductor element 5. I have.

The heat sink according to the present embodiment is manufactured in the following state. Polycrystalline diamond was formed on a Si wafer substrate having a thickness of 0.5 mm and a diameter of 2 inches by a hot filament CVD method for 45 hours.

(Conditions) Source gas Hydrogen: 1500 sccm Methane: 30 sccm Gas pressure 70 Torr W filament temperature 2000 ° C. to 2100 ° C. Polycrystalline diamond having a thickness of about 50 μm can be coated by synthesizing polycrystalline diamond under the above conditions. .
The coated polycrystalline diamond has a rough surface and is polished to 30 μm to eliminate the roughness. Then, Ti is used as the first intermediate bonding layer, Pt is used as the second intermediate bonding layer, and Au is used as the metal bonding layer. -Sn coated, G
The LD of aAs and InP is mounted. Such a state, L
It can be confirmed that D operates without any problem and oscillates the laser.

By adopting such a configuration and conditions, the thickness of the substrate base material is 200 μm or more, and the strength is secured. The thickness of the polycrystalline diamond layer is 60
Since it is 0 μm or less, heat radiation characteristics are also ensured. The thickness of the metal bonding layer is defined in the range of 2 μm to 5 μm.
Thereby, the difference in the coefficient of thermal expansion between the substrate and the semiconductor element can be set within an allowable range. Therefore, generation of stress due to a difference in the coefficient of thermal expansion can be reduced. Further, the bonding strength between the crystalline diamond layer and the metal bonding layer is increased. Therefore, the stress generated by the thermal expansion can be absorbed without causing a crack or the like in the metal bonding layer. The thermal conductivity of the polycrystalline diamond layer has a predetermined value in the range of room temperature to 400 ° C. and in the range of 500 W / m · K to 2000 W / m · K. Therefore, the heat radiation characteristics of the heat sink are improved. Therefore, heat generated by the semiconductor element can be effectively released. Furthermore, the difference in elongation due to the difference in the coefficient of thermal expansion between the constituent materials of the polycrystalline diamond layer, the metal bonding layer, the first intermediate bonding layer, and the second intermediate bonding layer can be kept within an allowable range, and the heat radiation Characteristics can be secured. Therefore, the semiconductor element is less susceptible to adverse effects such as cracks due to heat generation. As a result, it is possible to provide a heat sink that can absorb heat generated by the semiconductor element and withstand thermal expansion.

As shown in FIG. 2, a heat sink capable of absorbing the heat generated by the semiconductor element and resisting thermal expansion is similarly provided even if the structure does not include the first intermediate bonding layer 8a and the second intermediate bonding layer 8b. Can be provided.

As shown in FIGS. 3 and 4, when the polycrystalline diamond layer 3 is provided on the upper and lower surfaces of the substrate base material 2, the substrate base material 2 and the polycrystalline The stress caused by the difference in the elongation of the diamond layer 2 is absorbed by the upper and lower surfaces, so that the substrate is less likely to be bent and more stable.

As shown in FIG. 5 and FIG. 6, in order to obtain a more stable substrate which is unlikely to be bent, the maximum amount of bending δ is 5 μm or less for a length l of 10 mm from the beginning. An original deflection that becomes convex with respect to the semiconductor element 5 having a radius of curvature of 2.5 m or more may be provided. As a result, the substrate base material 2 has a higher coefficient of thermal expansion than the polycrystalline diamond layer 3, so that the difference in the coefficient of thermal expansion causes the substrate base material 2 to expand more than the polycrystalline diamond layer 3. For this reason, a bending that is concave with respect to the semiconductor element 5 in a direction opposite to the original bending that is convex with respect to the semiconductor element 5 occurs. As a result, a heat sink that is less likely to adversely affect the semiconductor element 15 even if deformation due to thermal expansion occurs. The reason for defining the radius of curvature to be 2.5 m or more is that if the radius of curvature is smaller than 2.5 m,
This is because, due to the influence, the thickness of the polycrystalline diamond layer 3 is partially different, causing a partial difference in heat conduction characteristics and a difference in heat radiation characteristics.

(Second Embodiment) The structure of a heat sink according to a second embodiment is the same as that of the first embodiment shown in FIG. 1, and is manufactured in the following state.

A polycrystalline diamond film was formed on a 0.5 mm thick 20 × 20 mm Si substrate by microwave plasma CVD for 50 hours.

(Conditions) Raw material gas Hydrogen: 300 sccm Methane: 8 sccm Gas pressure 100 Torr Microwave oscillation output 400 W By synthesizing polycrystalline diamond under the above conditions, a polycrystalline diamond having a thickness of about 60 μm can be coated.
The coated polycrystalline diamond has a rough surface and is polished to 30 μm to eliminate the roughness. Thereafter, Ti is used as the first intermediate bonding layer, Pt is used as the second intermediate bonding layer, and Au is used as the metal bonding layer. -Sn coated, G
The LD of aAs and InP is mounted. In such a state,
It can be confirmed that the LD operates without any problem and oscillates the laser.

By adopting such a configuration and conditions, the thickness of the substrate base material is 200 μm or more, and the strength is secured. The thickness of the polycrystalline diamond layer is 60
Since it is 0 μm or less, heat radiation characteristics are also ensured. The thickness of the metal bonding layer is defined in the range of 2 μm to 5 μm.
Thereby, the difference in the coefficient of thermal expansion between the substrate and the semiconductor element can be set within an allowable range. Therefore, generation of stress due to a difference in the coefficient of thermal expansion can be reduced. Further, the bonding strength between the crystalline diamond layer and the metal bonding layer is increased. Therefore, the stress generated by the thermal expansion can be absorbed without causing a crack or the like in the metal bonding layer. The thermal conductivity of the polycrystalline diamond layer has a predetermined value in the range of room temperature to 400 ° C. and in the range of 500 W / m · K to 2000 W / m · K. Therefore, the heat radiation characteristics of the heat sink are improved. Therefore, heat generated by the semiconductor element can be effectively released. Furthermore, the difference in elongation due to the difference in the coefficient of thermal expansion between the constituent materials of the polycrystalline diamond layer, the metal bonding layer, the first intermediate bonding layer, and the second intermediate bonding layer can be kept within an allowable range, and the heat radiation Characteristics can be secured. Therefore, the semiconductor element is less susceptible to adverse effects such as cracks due to heat generation. As a result, it is possible to provide a heat sink that can absorb heat generated by the semiconductor element and withstand thermal expansion.

As shown in FIG. 2, even if the structure does not include the first intermediate bonding layer 8a and the second intermediate bonding layer 8b, a heat sink capable of absorbing heat generated by the semiconductor element and withstanding thermal expansion is similarly provided. Can be provided.

As shown in FIGS. 3 and 4, when the polycrystalline diamond layer 3 is provided on the upper and lower surfaces of the substrate base material 2, the substrate base material 2 and the polycrystalline diamond layer are provided more than when only one surface is provided. The stress caused by the difference in the elongation of the diamond layer 2 is absorbed by the upper and lower surfaces, so that the substrate is less likely to be bent and more stable.

As shown in FIG. 5 and FIG. 6, in order to obtain a more stable substrate which is unlikely to be bent, the maximum amount of bending δ is 5 μm or less for a length l of 10 mm from the beginning. An original deflection that becomes convex with respect to the semiconductor element 5 having a radius of curvature of 2.5 m or more may be provided. As a result, the substrate base material 2 has a higher coefficient of thermal expansion than the polycrystalline diamond layer 3, so that the difference in the coefficient of thermal expansion causes the substrate base material 2 to expand more than the polycrystalline diamond layer 3. For this reason, a bending that is concave with respect to the semiconductor element 5 in a direction opposite to the original bending that is convex with respect to the semiconductor element 5 occurs. As a result, a heat sink that is less likely to adversely affect the semiconductor element 15 even if deformation due to thermal expansion occurs. The reason for defining the radius of curvature to be 2.5 m or more is that if the radius of curvature is smaller than 2.5 m,
This is because, due to the influence, the thickness of the polycrystalline diamond layer 3 is partially different, causing a partial difference in heat conduction characteristics and a difference in heat radiation characteristics.

(Third Embodiment) The structure of a heat sink according to a third embodiment is the same as that of the first embodiment shown in FIG. 1, and is manufactured in the following state.

Polycrystalline diamond was formed on an AlN substrate having a thickness of 0.6 mm and a size of 62 × 45 mm by a hot filament CVD method for 30 hours.

(Conditions) Source gas Hydrogen: 1500 sccm Methane: 30 sccm Gas pressure 70 Torr W filament temperature 2000 ° C. to 2100 ° C. By synthesizing polycrystalline diamond under the above conditions, a polycrystalline diamond having a thickness of about 30 μm can be coated. .
The coated polycrystalline diamond has a rough surface and is polished to 20 μm to eliminate the roughness. Thereafter, Ti is used as the first intermediate bonding layer, Pt is used as the second intermediate bonding layer, and Au is used as the metal bonding layer. -Sn coated, G
The LD of aAs and InP is mounted. In such a state,
It can be confirmed that the LD operates without any problem and oscillates the laser.

By adopting such a configuration and conditions, the thickness of the substrate base material is 200 μm or more, and the strength is secured. The thickness of the polycrystalline diamond layer is 60
Since it is 0 μm or less, heat radiation characteristics are also ensured. The thickness of the metal bonding layer is defined in the range of 2 μm to 5 μm.
Thereby, the difference in the coefficient of thermal expansion between the substrate and the semiconductor element can be set within an allowable range. Therefore, generation of stress due to a difference in the coefficient of thermal expansion can be reduced. Further, the bonding strength between the crystalline diamond layer and the metal bonding layer is increased. Therefore, the stress generated by the thermal expansion can be absorbed without causing a crack or the like in the metal bonding layer. The thermal conductivity of the polycrystalline diamond layer has a predetermined value in the range of room temperature to 400 ° C. and in the range of 500 W / m · K to 2000 W / m · K. Therefore, the heat radiation characteristics of the heat sink are improved. Therefore, heat generated by the semiconductor element can be effectively released. Furthermore, the difference in elongation due to the difference in the coefficient of thermal expansion between the constituent materials of the polycrystalline diamond layer, the metal bonding layer, the first intermediate bonding layer, and the second intermediate bonding layer can be kept within an allowable range, and the heat radiation Characteristics can be secured. Therefore, the semiconductor element is less susceptible to adverse effects such as cracks due to heat generation. As a result, it is possible to provide a heat sink that can absorb heat generated by the semiconductor element and withstand thermal expansion.

As shown in FIG. 2, even if the structure does not include the first intermediate bonding layer 8a and the second intermediate bonding layer 8b, the heat sink capable of absorbing the heat generated by the semiconductor element and withstanding the thermal expansion is similarly provided. Can be provided.

As shown in FIGS. 3 and 4, when the polycrystalline diamond layer 3 is provided on the upper and lower surfaces of the substrate base material 2, the substrate base material 2 and the polycrystalline The stress caused by the difference in the elongation of the diamond layer 2 is absorbed by the upper and lower surfaces, so that the substrate is less likely to be bent and more stable.

As shown in FIG. 5 and FIG. 6, in order to obtain a more stable substrate that is unlikely to be bent, the heat sink is provided with a maximum bending amount δ of 5 μm or less for a length l of 10 mm from the beginning. An original deflection that becomes convex with respect to the semiconductor element 5 having a radius of curvature of 2.5 m or more may be provided. As a result, the substrate base material 2 has a higher coefficient of thermal expansion than the polycrystalline diamond layer 3, so that the difference in the coefficient of thermal expansion causes the substrate base material 2 to expand more than the polycrystalline diamond layer 3. For this reason, a bending that is concave with respect to the semiconductor element 5 in a direction opposite to the original bending that is convex with respect to the semiconductor element 5 occurs. As a result, a heat sink that is less likely to adversely affect the semiconductor element 15 even if deformation due to thermal expansion occurs. The reason for defining the radius of curvature to be 2.5 m or more is that if the radius of curvature is smaller than 2.5 m,
This is because, due to the influence, the thickness of the polycrystalline diamond layer 3 is partially different, causing a partial difference in heat conduction characteristics and a difference in heat radiation characteristics.

(Fourth Embodiment) The structure of a heat sink according to a fourth embodiment is the same as that of the first embodiment shown in FIG. 1, and is manufactured in the following state.

Polycrystalline diamond was formed on one surface of an AlN substrate having a thickness of 0.6 mm and 62 × 45 mm for 25 hours by a hot filament CVD method.

(Conditions) Raw material gas Hydrogen: 1000 sccm Methane: 20 sccm Gas pressure 60 Torr W filament temperature 2000 ° C. to 2100 ° C. Polycrystalline diamond having a thickness of about 22 μm can be coated by synthesizing polycrystalline diamond under the above conditions. .
The deflection of the substrate was 100 μm in a convex shape on the diamond film side with respect to 62 mm, that is, the curvature radius was 4.8 m. Thereafter, the substrate base material was once removed from the synthesis apparatus, turned over, and synthesized again for 25 hours under the above conditions, to obtain a polycrystalline diamond having a thickness of about 22 μm. The deflection of the substrate at this stage is 62 μm and 60 μm convex on the side where the diamond film was first formed, that is, the curvature radius is 8.0 m.
Met. Since the coated polycrystalline diamond has a rough surface, both surfaces are polished to 15 μm to eliminate the roughness. Thereafter, Ti is used as the first intermediate bonding layer, Pt is used as the second intermediate bonding layer, and Au is used as the metal bonding layer. Cover with Sn and mount LD of GaAs and InP. In such a state, it can be confirmed that the LD operates without any problem and oscillates the laser.

By adopting such a configuration and conditions, the thickness of the substrate base material is 200 μm or more, and the strength is secured. The thickness of the polycrystalline diamond layer is 60
Since it is 0 μm or less, heat radiation characteristics are also ensured. The thickness of the metal bonding layer is defined in the range of 2 μm to 5 μm.
Thereby, the difference in the coefficient of thermal expansion between the substrate and the semiconductor element can be set within an allowable range. Therefore, generation of stress due to a difference in the coefficient of thermal expansion can be reduced. Further, the bonding strength between the crystalline diamond layer and the metal bonding layer is increased. Therefore, the stress generated by the thermal expansion can be absorbed without causing a crack or the like in the metal bonding layer. The thermal conductivity of the polycrystalline diamond layer has a predetermined value in the range of room temperature to 400 ° C. and in the range of 500 W / m · K to 2000 W / m · K. Therefore, the heat radiation characteristics of the heat sink are improved. Therefore, heat generated by the semiconductor element can be effectively released. Furthermore, the difference in elongation due to the difference in the coefficient of thermal expansion between the constituent materials of the polycrystalline diamond layer, the metal bonding layer, the first intermediate bonding layer, and the second intermediate bonding layer can be kept within an allowable range, and the heat radiation Characteristics can be secured. Therefore, the semiconductor element is less susceptible to adverse effects such as cracks due to heat generation. As a result, it is possible to provide a heat sink that can absorb heat generated by the semiconductor element and withstand thermal expansion.

As shown in FIG. 2, even if the structure does not include the first intermediate bonding layer 8a and the second intermediate bonding layer 8b, a heat sink capable of absorbing heat generated by the semiconductor element and withstanding thermal expansion is similarly provided. Can be provided.

As shown in FIGS. 3 and 4, when the polycrystalline diamond layer 3 is provided on the upper and lower surfaces of the substrate base material 2, the substrate base material 2 and the polycrystalline The stress caused by the difference in the elongation of the diamond layer 2 is absorbed by the upper and lower surfaces, so that the substrate is less likely to be bent and more stable.

As shown in FIG. 5 and FIG. 6, in order to obtain a more stable substrate which is unlikely to be bent, a heat sink is provided with a maximum bending amount δ of 5 μm or less for a length l of 10 mm from the beginning. An original deflection that becomes convex with respect to the semiconductor element 5 having a radius of curvature of 2.5 m or more may be provided. As a result, the substrate base material 2 has a higher coefficient of thermal expansion than the polycrystalline diamond layer 3, so that the difference in the coefficient of thermal expansion causes the substrate base material 2 to expand more than the polycrystalline diamond layer 3. For this reason, a bending that is concave with respect to the semiconductor element 5 in a direction opposite to the original bending that is convex with respect to the semiconductor element 5 occurs. As a result, a heat sink that is less likely to adversely affect the semiconductor element 15 even if deformation due to thermal expansion occurs. The reason for defining the radius of curvature to be 2.5 m or more is that if the radius of curvature is smaller than 2.5 m,
This is because, due to the influence, the thickness of the polycrystalline diamond layer 3 is partially different, causing a partial difference in heat conduction characteristics and a difference in heat radiation characteristics.

[0053]

According to the first to ninth aspects of the present invention, at least one surface of a substrate base material made of a nonmetallic inorganic material having relatively good thermal conductivity has a thickness of 5 μm to 60 μm. By covering the crystal diamond layer, the heat conduction characteristics of the entire heat sink are improved. In addition, the metal matrix substrate, which has a higher coefficient of thermal expansion than the semiconductor element, is coated with a polycrystalline diamond layer with a lower coefficient of thermal expansion. By doing so, the coefficient of thermal expansion of the semiconductor element, which is an intermediate value between the metal base material substrate and the diamond layer, can be made uniform, and a decrease in the characteristics of the semiconductor element can be suppressed. As a result, it is possible to provide a heat sink that has a constant coefficient of thermal expansion, has heat radiation properties, and can prevent a decrease in the characteristics of the semiconductor element.

Also, AlN is used as a substrate base material,
When mounting a GaAs or InP LD, the substrate
Polycrystalline if the thickness of the base material is specifically 0.5 mm
The thickness of the diamond layer is in the range of 10 μm to 50 μm
When the coefficient of thermal expansion in the in-plane direction of the diamond surface is
3.0 to 4.0 × 10 in the range of^-6/ ℃
The stress value on the semiconductor device due to the difference between the heat dissipation and the coefficient of thermal expansion.
It is a combination that does not cause performance degradation as a semiconductor element.
You. Also, 0.5 mm thick Si was used as the substrate base material.
If the thickness of the polycrystalline diamond layer is
Thermal expansion coefficient in the in-plane direction of the diamond surface in the range of 0 μm
Is in the range of room temperature to 400 ° C. and 3.0 to 3.3 × 10^-6/ ℃
Thus, a suitable configuration is obtained. Furthermore, the thickness of 0.5mm
When using SiC, the thickness of the polycrystalline diamond layer is
In-plane direction of the diamond surface within the range of 5 μm to 45 μm
Has a coefficient of thermal expansion in the range of room temperature to 400 ° C. of 3.0 to 4.0 ×.
10 ^-6/ ° C, which is a suitable configuration. Al described above
0.5mm thickness of N, SiC, Si is all thickness
Instead of polycrystalline diamond corresponding to the thickness of the substrate base material
The appropriate thickness of the layer is determined.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a heat sink having a first intermediate bonding layer and a second intermediate bonding layer used in a semiconductor device of the present invention.

FIG. 2 is a cross-sectional view showing a structure of a heat sink having no first intermediate bonding layer and no second intermediate bonding layer used in the semiconductor device of the present invention.

FIG. 3 shows a semiconductor device according to the present invention, having a first intermediate bonding layer and a second intermediate bonding layer, wherein the polycrystalline diamond layer has a thickness of 2 mm;
FIG. 4 is a cross-sectional view showing the structure of a layer heat sink.

FIG. 4 is a cross-sectional view showing the structure of a heat sink having no first intermediate bonding layer and no second intermediate bonding layer and having two polycrystalline diamond layers, which is used in the semiconductor device of the present invention.

FIG. 5 is a cross-sectional view showing a structure of a heat sink having a first intermediate bonding layer and a second intermediate bonding layer and having a flexure used in the semiconductor device of the present invention.

FIG. 6 is a cross-sectional view showing a structure of a heat sink having a first intermediate bonding layer and a second intermediate bonding layer and having a flexure, which is used for the semiconductor device of the present invention.

FIG. 7 is a cross-sectional view illustrating a structure of a heat sink of a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Package 2 Substrate base material 3 Polycrystalline diamond layer 4 Metal bonding layer 5 Semiconductor element 6 Lead frame 7 Bonding wire 8a First intermediate bonding layer 8b Second intermediate bonding layer

Claims (9)

[Claims] 1. A base material made of a nonmetallic inorganic material having upper and lower main surfaces and having a thickness between the upper and lower main surfaces of 200 μm to 600 μm, and at least one of the upper and lower main surfaces of the substrate base material A polycrystalline diamond layer having a thickness of 5 μm to 60 μm formed on the upper side, wherein a semiconductor element is provided on the surface of the polycrystalline diamond layer. 2. The heat sink according to claim 1, wherein the polycrystalline diamond layer is provided on both the upper and lower main surfaces of the substrate base material. 3. An Au, Ag, Si, Ge, Sn, P formed in a predetermined region on the surface of the polycrystalline diamond layer.
The heat sink according to claim 1, further comprising a metal bonding layer having a thickness of 2 μm to 5 μm made of at least one metal selected from the group consisting of d and In. 4. A method for forming a Ti, Zr, Hf, Nb, Ta, C
1 μm thick made of at least one material selected from oxides, carbides, nitrides and carbonitrides of at least one material selected from the group consisting of r, Mo, W, Au, Ni and V A first intermediate bonding layer having a thickness of ４4 μm, and Mo, Ni, Pd,
A second intermediate bonding layer of at least one selected from the group consisting of Pt and Au and having a thickness of 2 μm to 5 μm, formed on a surface of the second intermediate bonding layer, and a semiconductor element mounted on the surface; Au, Ag, Si, Ge,
The heat sink according to claim 1, further comprising a metal bonding layer having a thickness of 2 μm to 5 μm and made of at least one metal selected from the group consisting of Sn, Pd, and In. 5. The method according to claim 1, wherein the substrate base material is Si, AlN, Si.
C, Si ₃ N ₄ or Si, AlN, SiC, Si ₃ N
₄ at least one member selected from the group of non-metallic material is formed by a sintered body, a heat sink according to claim 1. 6. The polycrystalline diamond layer has a thermal conductivity in the range of room temperature to 400.degree.
A predetermined value within a range of 00 W / m · K.
5. The heat sink according to any one of 5. 7. The heat sink according to claim 1, wherein the heat sink has a convex bending on the semiconductor element side, and has a radius of curvature of 2.5 m or more at an arbitrary portion. 8. The heat sink according to claim 1, wherein the material and thickness of the polycrystalline diamond layer and the base material of the substrate are set to predetermined materials and thicknesses, respectively, so that heat in an in-plane direction of a main surface of the polycrystalline diamond layer is obtained. Expansion coefficient from room temperature to 400
The heat sink according to claim 1, wherein the heat sink is set to a predetermined value within a range of 2.3 × 10 ^{−6 to} 4.0 × 10 ⁻⁶ / ° C. in a range of ° C. 9. 9. The heat sink according to claim 1, wherein said polycrystalline diamond layer is a polycrystalline diamond layer formed by a vapor phase synthesis method.