JP2019091943A - Semiconductor device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device having high heat radiation efficiency from a semiconductor component to a heat radiation member. A semiconductor device (1) according to an embodiment of the present invention includes a substrate (11) having a semiconductor element (12) mounted on an upper surface (11a), a heat dissipation member (20), a lower surface (11b) of the substrate (11) and an upper surface (20a) of the heat dissipation member (20). An area of an upper surface 20a of the heat dissipation member 20 is larger than an area of a lower surface 11b of the substrate 11, and the metal bonding layer 30 includes the entire lower surface 11b of the substrate 11. And has a larger area than the lower surface 11b of the substrate 11, and the thermal conductivity of the metal bonding layer 30 is higher than the thermal conductivity of the heat dissipation member 20. [Selection diagram] Fig. 3

Description

  The present invention relates to a semiconductor device, and more particularly to a semiconductor device with high heat dissipation efficiency and a method of manufacturing the same.

In semiconductor components including high-power semiconductor devices (for example, semiconductor light emitting devices for vehicles), it is important to efficiently dissipate the heat generated by the semiconductor devices during use. Therefore, the semiconductor components are attached to a heat dissipation member formed of a material having high thermal conductivity to improve the heat dissipation.
In a semiconductor component, a ceramic substrate having excellent thermal conductivity can be used as a substrate on which a semiconductor element is mounted (Patent Documents 1 to 3). When the semiconductor component is attached to the heat dissipation member, the ceramic substrate of the semiconductor component is joined to the heat dissipation member. As a joining method in that case, it is known to use solder (patent documents 1 and 2) and a silver paste (patent document 3), for example.
Moreover, the normal temperature bonding method is known as another method of joining a several member (patent document 4). In the normal temperature bonding method, a plurality of members can be bonded by forming a metal film on the bonding surface of each member under vacuum and bringing the metal films into contact with each other. It is thought that heat dissipation performance, heat diffusion performance and the like are improved by using this room temperature bonding method for bonding a semiconductor component and a heat dissipation member.

JP, 2009-194275, A JP, 2013-055218, A JP, 2010-166019, A JP, 2008-207221, A

In the bonding methods disclosed in Patent Literatures 1 to 3, the thermal conductivity of the solder and the silver paste is not sufficiently high, and the heat dissipation efficiency from the semiconductor component to the heat dissipation member is not sufficient.
In the room temperature bonding method disclosed in Patent Document 4, since the semiconductor component and the heat radiating member are bonded by the metal material having high thermal conductivity, the heat radiation efficiency from the semiconductor component to the heat radiating member is higher than in Patent Documents 1 to 3. Is high. However, due to the increase in the amount of heat generation associated with the increase in output of semiconductor elements, further improvement in heat dissipation efficiency is required.
Therefore, an object of the embodiments according to the present invention is to provide a semiconductor device having high heat dissipation efficiency from a semiconductor component to a heat dissipation member and a method of manufacturing the same.

  A semiconductor device according to an embodiment of the present invention includes a substrate on which a semiconductor element is mounted on a top surface, a heat dissipation member, and a metal bonding layer joining the bottom surface of the substrate and the top surface of the heat dissipation member. The area of the upper surface of the member is larger than the area of the lower surface of the substrate, and the metal bonding layer is in contact with the entire lower surface of the substrate and has a larger area than the lower surface of the substrate. The thermal conductivity is higher than the thermal conductivity of the heat dissipation member.

In addition, a method of manufacturing a semiconductor device according to an embodiment of the present invention,
1) placing a semiconductor element on the upper surface of the substrate;
2) forming a first metal layer on the lower surface of the substrate;
3) forming a second metal layer having an area larger than the lower surface of the substrate on the upper surface of the heat dissipation member;
4) bringing the first metal layer and the second metal layer into contact with each other to bond them;
A metal bonding layer composed of the first metal layer and the second metal layer is characterized by having a thermal conductivity higher than that of the heat dissipation member.

  According to the semiconductor device of the embodiment of the present invention, a metal bonding layer having a thermal conductivity higher than that of the heat dissipation member is used for bonding the substrate on which the light emitting element is mounted and the heat dissipation member. By making the area larger than the area of the substrate, the heat generated in the light emitting element can be spread by the metal bonding layer and then moved to the heat radiating member, so that the heat radiation efficiency can be enhanced.

FIG. 1 is a schematic perspective view showing a state where the semiconductor device according to the first embodiment of the present invention is mounted on an external heat dissipation member. FIG. 2 is a partially enlarged top view of the semiconductor device and the external heat dissipation member shown in FIG. FIG. 3 is a schematic cross-sectional view of the semiconductor device taken along line AA of FIG. FIG. 4 is a partial enlarged cross-sectional view for explaining the heat dissipation path of the semiconductor device according to the first embodiment. FIG. 5 is a cross-sectional view showing a modification of the semiconductor device according to the first embodiment. 6A to 6F are partial enlarged cross-sectional views showing various aspects of the metal bonding layer included in the semiconductor device. FIG. 7 is a cross-sectional view showing another modified example of the semiconductor device according to the embodiment of the present invention. FIGS. 8A to 8C are cross-sectional views for explaining the manufacturing process of the semiconductor device. FIGS. 9A and 9B are cross-sectional views for explaining the manufacturing process of the semiconductor device. 10 (a) and 10 (b) are cross-sectional views for describing the manufacturing process of the semiconductor device. FIG. 11 is a partially enlarged cross-sectional view showing an aspect of lamination of a metal film for forming the metal bonding layer illustrated in FIGS. 6 (a) to 6 (f). FIG. 12 is a cross-sectional TEM image of the metal bonding layer.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In the following description, terms that indicate a specific direction or position (for example, "upper", "lower", "right", "left" and other terms including those terms) are used as needed. . The use of these terms is to facilitate the understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Further, portions denoted by the same reference numerals in multiple drawings indicate the same portions or members.

Embodiment 1
In this embodiment, a semiconductor device in which a semiconductor element is a light emitting element (that is, a semiconductor light emitting device) is described as an example.
A semiconductor device (semiconductor light emitting device) 1 according to the present embodiment and an external heat dissipation member (heat sink) 50 on which the semiconductor device 1 is mounted are illustrated in FIGS. The semiconductor light emitting device 1 includes a semiconductor component (light emitting component) 10, a heat radiating member (heat spreader) 20, and a metal bonding layer 30.

  As shown in FIGS. 2 to 3, the light emitting component 10 includes a substrate 11 and a semiconductor element (light emitting element) 12 mounted on the upper surface 11 a thereof. The substrate 11 may be a main body of an insulating material with good heat dissipation, provided with metal wiring for energizing the light emitting element 12. In the present embodiment, a ceramic substrate using a ceramic material for the main body is used.

  The heat spreader 20 is a plate-like member for radiating heat generated by the light emitting element 12, and the heat spreader 20 can be used alone or in combination with a heat sink to improve the radiation efficiency. The area of the upper surface 20a of the heat spreader 20 is larger than the area of the entire lower surface 11b of the substrate 11 (see FIGS. 1 and 2). In the present embodiment, the heat spreader 20 is illustrated as a heat dissipating member to which the light emitting component 10 is attached, but the heat sink 50 may be used as a heat dissipating member. In that case, the light emitting component 10 is directly attached to the heat sink 50 without the heat spreader 20.

The upper surface 20 a of the heat spreader 20 is provided with a metal bonding layer 30 covering at least a part of the upper surface 20 a. The light emitting component 10 is bonded to the heat spreader 20 by the metal bonding layer 30. More specifically, the metal bonding layer 30 bonds the lower surface 11 b of the substrate 11 of the light emitting component 10 to the upper surface 20 a of the heat spreader 20. The area of the metal bonding layer 30 is larger than the area of the lower surface 11 b of the substrate 11 of the light emitting component 10. And when arrange | positioning the light emitting component 10 on the metal joining layer 30, it is arrange | positioned so that the lower surface 11b of the board | substrate 11 may entirely enter in the area | region in which the metal joining layer 30 is formed. Thereby, the entire lower surface 11 b of the substrate 11 contacts the metal bonding layer 30. The thermal conductivity of the metal bonding layer 30 is higher than the thermal conductivity of the heat spreader 20.
The heat radiation efficiency of the semiconductor light emitting device 1 can be improved by the metal bonding layer 30 having the above-described features.

The reason for the improvement of the heat dissipation efficiency is not clear, but is considered to be due to the following mechanism.
As shown in FIG. 4, the heat generated in the light emitting element 12 spreads in the substrate 11, is transmitted to the metal bonding layer 30, and further moves to the heat spreader 20. The heat tends to be concentrated in the region 20 u immediately below the substrate 11 in the heat spreader 20. In order to enhance the heat radiation efficiency, it is effective to promote the heat conduction to the area (outer edge area 20x) outside the area directly below the area 20u.

In the semiconductor light emitting device 1 according to the present embodiment, since the area of the metal bonding layer 30 is larger than the area of the entire lower surface 11 b of the substrate 11, when the light emitting component 10 is disposed on the metal bonding layer 30, At least a portion of the outer periphery extends to the outside of the substrate 11 (this extended portion is referred to as “the extended portion 30x”).
The heat radiation path from the substrate 11 (for example, point P ₁ ) to the outer edge region 20 x (for example, point P ₂ ) of the heat spreader 20 includes a first heat radiation path T ₁ which does not pass through the outer extension portion 30 x of the metal bonding layer 30; there is a first heat radiation path _{T 2} through the portion 30x.
In the first heat dissipation path _{T 1,} first, from the point _{P 1,} pass through the metal bonding layer 30 in the thickness direction (-z direction), the process proceeds directly under area 20u of the heat spreader 20 (path _t 1a). Thereafter, the heat spreader 20 travels in the lateral direction (−x direction) to reach the point P ₂ (path t 1 _b ).
On the other hand, in the second heat dissipation path T _2, first, after traveling from point P ₁ to the metal bonding layer 30, moving towards (-x direction in FIG. 4) perpendicular to the metal bonding layer 30 and the thickness direction And reach the extension 30x (path t _2a ). Thereafter, it proceeds to the thickness direction of the metal bonding layer 30 (-z direction), and reaches the point _{P 2} (path _t 2b).

When these two heat radiation paths are compared, the path t _{1 a} of the first heat radiation path T ₁ and the path t _{2 b} of the _second heat radiation path T ₂ are both vertically downward (−z) by approximately the same distance in the heat spreader 20. Because there is no difference in heat conductivity (heat conductivity), the
On the other hand, path t 1 _b of first heat release path T ₁ and path t _{2 a} of _second heat release path T ₂ proceed in the lateral direction (−x direction) by approximately the same distance, but path t 1 _b is metal bonding layer 30. Since the path t _{2 a} passes through the heat spreader 20 through the inside, the heat conductivity becomes different. As described above, since the thermal conductivity of the metal bonding layer 30 is higher than the thermal conductivity of the heat spreader 20, the path t ₂ a passing through the metal bonding layer 30 is more thermally conductive than the path t 1 _b passing through the heat spreader 20. It is excellent in conductivity.
In other words, more of the second heat radiation path T ₂ is, than the first heat dissipation path T _1, a high heat dissipation efficiency. In the semiconductor light emitting device 1 according to the present embodiment, since the metal bonding layer 30 includes the extended portion 30 x and the thermal conductivity of the metal bonding layer 30 is higher than the thermal conductivity of the heat spreader 20, the heat spreader from the substrate 11 is until 20 of the outer edge region 20x, the second heat radiation path T ₂ is formed with high heat dissipation efficiency. Thereby, the heat conduction to the outer edge region 20x is promoted, and the heat dissipation efficiency of the semiconductor light emitting device 1 can be improved.

  In the semiconductor light emitting device 1 shown in FIGS. 1 to 4, the metal bonding layer 30 is formed in the upper surface 20 a of the heat spreader 20 in a range excluding the edge 20 e (that is, the edge 20 e of the upper surface 20 a is a metal bonding Not covered by layer 30). More preferably, as in the semiconductor light emitting device 2 shown in FIG. 5, the entire surface of the upper surface 20 a of the heat spreader 20 is covered with the metal bonding layer 30. Thus, the area of the extended portion 30x of the metal bonding layer 30 is further increased, so that the heat dissipation efficiency of the semiconductor light emitting device 2 can be further improved.

  The thickness of the metal bonding layer 30 is preferably 1 nm or more and 10 μm or less. When the film thickness is in this range, the heat radiation efficiency of the heat radiation path passing through the metal bonding layer 30 can be enhanced, and an appropriate bonding strength between the substrate 11 and the heat spreader 20 can be obtained. In consideration of the productivity of the semiconductor light emitting device 1, the thickness is preferably 20 nm to 200 nm.

  The metal bonding layer 30 can be composed of a single metal film (see FIG. 6A). The metal bonding layer 30 can also be configured by laminating a plurality of metal films (see FIGS. 6B to 6F). The metal bonding layer 30 including a plurality of metal films further includes a metal bonding layer 30 (FIGS. 6B to 6C) including an odd number of metal films, and a metal bonding layer 30 including an even number of metal films. (FIG. 6 (d) to FIG. 6 (f)).

  FIG. 6 (b) shows a metal bonding layer 30 composed of three metal films 30a, 30b and 30c. In this example, two thick metal films 30a and 30c are provided on the lower surface 11b side of the substrate 11 and the upper surface 20a of the heat spreader 20, and a thin metal film 30b having a small thickness is provided between them. Is provided. In this embodiment, the two metal films 30a and 30c are formed of a metal material having high thermal conductivity (for example, Ag), and the one metal film 30b is formed of a metal material having high bonding properties (for example, Au or the like). The metal bonding layer 30 having a high thermal conductivity and a good bonding property can be obtained.

  FIG. 6 (c) shows a metal bonding layer 30 which similarly comprises three metal films 30d, 30e, and 30f. In this example, two thin metal films 30d and 30f having a small thickness are provided on the lower surface 11b side of the substrate 11 and the upper surface 20a of the heat spreader 20, and one thick metal film 30e is provided between them. Is provided. In this embodiment, two metal films 30d and 30f are formed of a metal material (such as Cr) having good bonding with the substrate 11 and the heat spreader 20, and one metal film 30e is a metal having high thermal conductivity. By forming it from a material (for example, Ag or the like), it is possible to obtain a metal bonding layer 30 having a high thermal conductivity and a good bonding property.

  FIG. 6 (d) shows a metal bonding layer 30 consisting of two metal films. In this example, the metal film on the lower surface 11 b side of the substrate 11 is referred to as a first metal layer 31, and the metal film on the upper surface 20 a side of the heat spreader 20 is referred to as a second metal layer 32. In this embodiment, the thermal conductivity can be obtained by forming both the first metal layer 31 and the second metal layer 32 from a metal material (such as Au) having relatively good thermal conductivity and bondability. And a metal bonding layer 30 having relatively good bonding properties.

FIG. 6E shows a metal bonding layer 30 composed of four metal films 31a, 31b, 32c, and 32d. In this example, two thick metal films (first metal film 31a and fourth metal film 32d) are provided on the lower surface 11b side of the substrate 11 and on the upper surface 20a side of the heat spreader 20. A thin two-layered metal film (a second metal film 31b and a third metal film 32c) is provided between the two. In this embodiment, the first metal film 31a and the fourth metal film 32d are formed of a metal material having high thermal conductivity (for example, Ag), and the second metal film 31b and the third metal between them are formed. By forming the film 32 c from a metal material (eg, Au or the like) having good bondability and high oxidation resistance, it is possible to obtain the metal bond layer 30 having high thermal conductivity and good bondability.
In the metal bonding layer 30 of FIG. 6E, the first metal layer 31 provided on the lower surface 11b side of the substrate 11 is formed of two metal films (first metal film 31a and second metal film 31b). The second metal layer 32 formed on the upper surface 20a side of the heat spreader 20 is formed of two metal films (third metal film 32c and fourth metal film 32d), and then the second metal is formed. It can be formed by bonding the film 31 b and the third metal film 32 c.

FIG. 6 (f) shows a metal bonding layer 30 which is also composed of four metal films 31e, 31f, 32g and 32h. In this example, two thin metal films 31e and 32h having a small thickness are provided on the lower surface 11b side of the substrate 11 and the upper surface 20a of the heat spreader 20, and a thick two-layer metal film 31f is provided therebetween. , 31g are provided. In this embodiment, the two metal films 31e and 32h are formed of a metal material (for example, Cr or the like) having a good bonding property with the substrate 11 and the heat spreader 20, and the two metal films 31f and 31g between them are By forming it from a metal material having high thermal conductivity (for example, Ag or the like), it is possible to obtain a metal bonding layer 30 having high thermal conductivity and good bonding.
In the metal bonding layer 30 of FIG. 6F, the first metal layer 31 provided on the lower surface 11 b side of the substrate 11 is formed of two metal films 31 e and 31 f and provided on the upper surface 20 a side of the heat spreader 20. The second metal layer 32 can be formed by forming two metal films 32g and 32h and then bonding the metal films 31f and 32g.

  The difference between the form of the metal bonding layer 30 as shown in FIGS. 6 (a) to 6 (c) and the form of the metal bonding layer 30 as shown in FIGS. 6 (d) to 6 (f) is mainly Due to differences in the manufacturing method. Although the details will be described later, the metal bonding layer 30 as shown in FIGS. 6A to 6C includes a metal film formed on the lower surface 11b of the substrate 11 and a metal film formed on the upper surface 20a side of the heat spreader 20. Can be formed by contacting and bonding under vacuum. On the other hand, the metal bonding layer 30 as shown in FIG. 6D to FIG. 6F is formed on the side of the first metal layer 31 formed on the lower surface 11b of the substrate 11 and on the side of the upper surface 20a of the heat spreader 20. The metal layer 32 can be formed by contact in air (that is, under an oxygen-containing atmosphere) and bonding.

  The “thermal conductivity of the metal bonding layer 30” refers to the metal material forming the metal film when the metal bonding layer 30 is formed of a single metal film as shown in FIG. 6A. Means the thermal conductivity of When the metal bonding layer 30 is formed of a laminate of a plurality of metal films, the thermal conductivity of the metal bonding layer 30 means the thermal conductivity of the entire metal bonding layer 30. Therefore, even if one of the plurality of metal films is formed of a metal material having a low thermal conductivity, if the other metal film is formed of a metal material having a high thermal conductivity, the metal bonding layer 30 The overall thermal conductivity can be increased.

  Further, in the present embodiment, “the thermal conductivity of the metal bonding layer 30 is higher than the thermal conductivity of the heat spreader 20” is defined. This definition is intended that, when the metal bonding layer 30 is formed of a plurality of metal films, the thermal conductivity of the metal bonding layer 30 as a whole is higher than the thermal conductivity of the heat spreader 20. That is, the definition does not mean that all the metal materials contained in the metal bonding layer 30 have a thermal conductivity higher than the thermal conductivity of the heat spreader 20. Therefore, even if a part of the plurality of metal films is formed of a metal material having a thermal conductivity smaller than that of the heat spreader 20, the other metal film has a thermal conductivity larger than that of the heat spreader 20. In the case where the entire metal bonding layer 30 has a thermal conductivity higher than that of the heat spreader 20 by being formed of a material, “the thermal conductivity of the metal bonding layer 30 is higher than the thermal conductivity of the heat spreader 20” There is no problem at all in satisfying the definition and using it as the metal bonding layer 30 in the present embodiment.

The thermal conductivity of the entire metal bonding layer 30 composed of a plurality of metal films can be determined from the measured value of the thermal resistance of the metal bonding layer 30. For example, in the semiconductor device 1 as shown in FIG. 3, (1) the thermal resistance R1 from the upper surface 11a of the substrate 11 to the upper surface 20a of the heat spreader 20 is measured, and (2) the thermal resistance R2 (specified value) of the substrate 11 By using it, thermal resistance Rm = R1-R2 of the metal bonding layer 30 can be determined. Further, in the present specification, the thickness t ₃₀ (m) of the metal bonding layer 30 is the heat resistance Rm (k / W) of the metal bonding layer 30 and the total area A (m ² ) of the metal bonding layer 30. The thermal conductivity (W · m ⁻¹ · K ⁻¹ ) of the entire metal bonding layer 30 can be determined by dividing (calculation formula: t ₃₀ / (Rm × A)).

Further, in the present specification, the calculation formula of the thermal conductivity T of the metal multilayer film composed of a plurality of metal films is defined as follows.
The thermal conductivity T of the metal multilayer film in which the metal layer composed of metal _α of thermal conductivity T _{α and} the metal layer composed of metal _β of thermal conductivity T _β are laminated at a film thickness ratio a: b is It can be determined by equation (1).
T = T _α × T _β × (a + b) / (a × T _β + b × T _α ) (1)

In addition, the above-mentioned Formula (1) was calculated | required by the following procedures.
A formula for calculating the thermal conductivity T of a metal multilayer film in which a metal layer composed of metal _α of thermal conductivity T _α and a metal layer composed of metal _β of thermal conductivity T _β are laminated at a film thickness ratio a: b consider.
Thermal resistance Rm of the entire metal multilayer film, the Rm = R α ₊ R _β using the thermal resistance R _beta thermal resistance R _alpha and metal beta metal alpha. This is described as Rm = t _α / (T _α × A) + t _β / (T _β × A) (1-1).
(t _α : thickness of metal α, t _β : thickness of metal β, A: area of metal multilayer film)
Further, the thermal conductivity T of the entire metal multilayer film has a relationship of T = t ₃₀ / (Rm × A) (1-2).
Therefore, when (1-1) is substituted for (1-2) above, T = t ₃₀ / (t _α / T _α + t _β / T _β ), and in summary, T = T _α × T _β × t the _{30 / (t α × T β} + t β × T α).
The thickness a, t _beta film thickness b in t _alpha, and substituting thickness a + b to t _30,
T = _Tα × _Tβ × (a + b) / (a × _Tβ + b × T _α ) (1)

Note that, as described later, when the metal bonding layer 30 has a step (see FIG. 10), the thickness t ₃₂ of the extended portion ₃₀ x is “the thickness t ₃₀ of the metal bonding layer ₃₀ ” and the metal including the extended portion ₃₀ x Let the area of the bonding layer 30 be “total area A”. The thermal conductivity calculated by the above-mentioned equation (1) corresponds to the thermal conductivity of the second metal layer 32 in FIGS. 11 (b) and 11 (c).

The thermal conductivity of the metal bonding layer 30 is determined by substituting specific numerical values into the formula (1). The thermal conductivity of the metal bonding layer 30 stacked in three layers as shown in FIG. 6B is obtained. Two layers (metal films 30a and 30c) are formed of Ag (thermal conductivity 427 W · m ^-1 · K ^-1 ), and one layer (metal film 30b) between them is Au (thermal conductivity) It is formed of 315 W · m ^-1 · K ^-1 ). The ratio of the total thickness of the metal films 30a and 30c to the total thickness of the metal film 30b is 5: 1 (that is, the thickness of Ag is five times as thick as that of Au).
The approximate value of the thermal conductivity T of the metal bonding layer 30 is
T = 315 × 427 × 6 / (1 × 427 + 5 × 315) = 403.1 W · m ⁻¹ · K ⁻¹
It becomes. That is, the metal bonding layer 30 has a thermal conductivity higher than that of Cu (398 W · m ⁻¹ · K ⁻¹ ). Therefore, the metal bonding layer 30 made of Ag and Au can be used in combination with the heat dissipation member made of Cu.

  Referring again to FIGS. 1 and 2, when fixing the semiconductor light emitting device 1 to the heat sink 50, for example, screw holes may be provided in the heat spreader 20 and the heat sink 50 of the semiconductor light emitting device 1 and fixed. . In this case, in order to improve the thermal conductivity between the heat spreader 20 and the heat sink 50, it is preferable to interpose the heat release grease 80 or the like. Further, when the semiconductor light emitting device 1 is fixed to the heat sink 50, it can be soldered.

  The metal material used for the metal bonding layer 30 preferably has a melting point of 350 ° C. or more. When the semiconductor light emitting device 1 is soldered to the heat sink 50, it is possible to avoid melting of the metal bonding layer 30 during solder reflow (heating to 280 to 340 ° C.), so bonding failure between the light emitting component 10 and the heat spreader 20 And the like can be suppressed.

  Referring back to FIG. 3, in the semiconductor light emitting device 1 according to the present embodiment, the light emitting component 10 includes the light emitting element 12, the substrate 11, and the wavelength conversion member 13 and the light reflective molded body 15. It may be The wavelength conversion member 13 is a member for converting the wavelength of light from the light emitting element 12, and for example, a plate-like member containing a phosphor that converts blue light emission into yellow light can be used. The light reflective molded body 15 is formed of a material that reflects light (for example, a white resin material including a light reflective material such as titanium oxide particles). By covering the side surface of the light emitting element 12 and the side surface of the wavelength conversion member 13 with the light reflective molded body 15, it is possible to reflect light traveling in the lateral direction (x direction) and to suppress leakage of the light in the lateral direction. it can.

  Also, as in the semiconductor light emitting device 3 shown in FIG. 7, another type of light emitting component 210 can be used. The light emitting component 210 includes the light emitting element 12 mounted on the upper surface 11 a of the substrate 11, the wavelength conversion layer 213 covering the upper surface and the side surface of the light emitting element 12, and the resin molding 214 covering the light emitting element 12 and the wavelength conversion layer 213. Contains. The wavelength conversion layer 213 can be formed of, for example, a material containing a phosphor or the like that converts blue light emission into yellow light. The surface of the resin molded body 214 is hemispherically shaped like a convex lens, and the orientation of light from the light emitting element 12 can be controlled. The resin molded body 214 is formed of a translucent resin material.

  Next, a method of manufacturing the semiconductor light emitting device 1 according to the present embodiment will be described with reference to FIGS.

<Step 1) Preparation of light emitting component 10>
The light emitting element 12 is mounted on the upper surface 11 a of the substrate 11 provided with the wiring (see FIG. 8A). Note that one or more (three in FIG. 8A) light emitting elements 12 can be mounted. When the light emitting component 10 includes the wavelength conversion member 13 and the light reflective molded body 15, they are sequentially formed. First, the wavelength conversion member 13 is fixed on the light emitting element 12 with a transparent adhesive or the like (see FIG. 8B). Next, the side surface of the light emitting element 12 and the side surface of the wavelength conversion member 13 are covered with the light reflective molded body 15 (see FIG. 8C).

<Step 2) Formation of First Metal Layer 31>
The first metal layer 31 is formed on the lower surface 11b of the substrate 11 of the light emitting component 10 by sputtering (see FIG. 9A). First, the light emitting component 10 is placed in the vacuum chamber 71 of the sputtering apparatus 70. At this time, the position and the orientation of the light emitting component 10 are adjusted such that the lower surface 11 b of the substrate 11 faces the sputtering target 72. In FIG. 9A, since the sputtering target 72 is disposed on the upper side of the vacuum chamber 71, the light emitting component 10 is disposed immediately below the sputtering target 72 so that the lower surface 11b of the substrate 11 faces upward. A holding member 73 may be used to hold the light emitting component 10 at a predetermined position and direction.

<Step 3) Formation of Second Metal Layer 32>
The second metal layer 32 is formed on the upper surface 20a of the heat spreader 20 by sputtering (see FIG. 9B). At this time, the second metal layer 32 is formed so that the area of the second metal layer 32 is at least the area larger than the lower surface 11 b of the substrate 11.
First, the heat spreader 20 is placed in the vacuum chamber 71 of the sputtering apparatus 70. At this time, the position and the orientation of the heat spreader 20 are adjusted such that the upper surface 20 a of the heat spreader 20 faces the sputtering target 72. Similar to the film formation on the light emitting component 10, the heat spreader 20 is disposed immediately below the sputtering target 72 so that the upper surface 20 a of the heat spreader 20 faces upward.
A holding member 74 for holding the heat spreader 20 at a predetermined position and direction may be used. In this figure, the holding member 74 holds a portion (e.g., the edge 20e) of the upper surface 20a of the heat spreader 20, so the second metal layer is formed on the edge 20e of the upper surface 20a held by the holding member 74. 32 is not deposited.

<Step 4) Bonding Step of Metal Layers 31 and 32>
In the vacuum chamber 71 of the sputtering apparatus 70, the first metal layer 31 formed on the lower surface 11b of the substrate 11 of the light emitting component 10 and the second metal layer 32 formed on the upper surface 20a of the heat spreader 20 Contact (see FIG. 10 (a)). After the film formation in the vacuum chamber 71, the first metal layer 31 and the second metal layer 32 which are placed under vacuum as they are have high surface energy, and only by contacting them at normal temperature, atomic diffusion occurs Can be joined together. By this bonding, the boundary between the first metal layer 31 and the second metal layer 32 almost disappears, and a metal bonding layer 30 formed of a single metal film as shown in FIG. 6A, for example. Is formed.
When the first metal layer 31 and the second metal layer 32 are brought into contact with each other, the lower surface 11 b of the substrate 11 of the light emitting component 10 is formed on the upper surface 20 a of the heat spreader 20. The light emitting component 10 and the heat spreader 20 are aligned so as to be disposed at a desired position.

  When the first metal layer 31 and the second metal layer 32 are formed of a metal material (for example, Au or an Au alloy) which is excellent in oxidation resistance and has a large diffusion coefficient, 32 can also be bonded in the atmosphere (under an oxygen-containing atmosphere). Specifically, the first metal layer 31 and the second metal layer 32 are formed in the vacuum chamber 71, and then the light emitting component 10 and the heat spreader 20 are taken out of the vacuum chamber 71 to the atmosphere. Then, the first metal layer 31 formed on the lower surface 11 b of the substrate 11 of the light emitting component 10 is brought into contact with the second metal layer 32 formed on the upper surface 20 a of the heat spreader 20 at normal temperature in the air. Thereby, the first metal layer 31 and the second metal layer 32 can be bonded to each other. However, since the surface energy of the first metal layer 31 and the second metal layer 32 is reduced by taking out to the atmosphere, the boundary line between the first metal layer 31 and the second metal layer 32 Does not disappear. Therefore, as shown in FIG. 6 (d), for example, the metal bonding layer 30 is formed in a state in which the first metal layer 31 and the second metal layer 32 can be distinguished.

To summarize the effects of bonding under each atmosphere, bonding the metal layers 31 and 32 under vacuum can increase the bonding strength between the metal layers 31 and 32.
On the other hand, when the metal layers 31 and 32 are bonded in the atmosphere, the operation of aligning the light emitting component 10 and the heat spreader 20 at the time of bonding is easy. Therefore, it is easy to increase the positional accuracy of the light emitting component 10 with respect to the heat spreader 20, and it is possible to expect suppression of the defective product occurrence rate and improvement of the yield.

By the steps 1) to 4), the semiconductor light emitting device 1 in which the light emitting component 10 and the heat spreader 20 are joined by the metal bonding layer 30 can be obtained (see FIG. 10B). The metal bonding layer 30 formed by the above-described method has two thicknesses. One is in the region right under the light emitting component 10, a relatively thick portion of the film thickness _{t 33} (the thickness _{t 31} of the first metal layer 31 the sum of the thickness _{t 32} of the second metal layer 32) is there. The other, in the extension portion 30x, a relatively thin portion of the thickness _{t 32} (coincident with the thickness _{t 32} of the second metal layer 32). Thus, in the case of metal bonding layer 30 having different portions of the thickness of the second metal layer 32 thickness t _32, and the thickness t ₃₀ of the metal bonding layer 30. Since the extension 30x of the metal bonding layer 30 mainly contributes to the heat dissipation, the thickness of the extension 30x (that is, the film thickness t ₃₂ ) is treated as the thickness t ₃₀ of the metal bonding layer 30. I decided.

  Further, the metal bonding layer 30 illustrated in FIGS. 6A to 6F described above is a process 2) a process of forming the first metal layer 31, a process 3) a process of forming the second metal layer 32, And process 4) It can form by changing the conditions of the joining process of the metal layers 31 and 32 as follows.

(About the metal bonding layer 30 in FIG. 6 (a) and FIG. 6 (d))
First, the first metal layer 31 is formed on the lower surface 11b of the substrate 11 of the light emitting component 10, and the second metal layer 32 is formed on the upper surface 20a of the heat spreader 20 (see FIG. 11A). At this time, the first metal layer 31 and the second metal layer 32 are formed of the same metal material. When the first metal layer 31 and the second metal layer 32 are brought into contact under vacuum in the next metal film bonding step, as shown in FIG. 6A, a metal consisting of a single metal film Bonding layer 30 is formed. On the other hand, when the first metal layer 31 and the second metal layer 32 are brought into contact with each other in the atmosphere, as shown in FIG. 6D, the metal bonding layer 30 composed of the two metal layers 31 and 32 becomes It is formed.

(About the metal bonding layer 30 of FIG. 6 (b) and FIG. 6 (e))
First, the first metal film 31 a and the second metal film 31 b are stacked in this order on the lower surface 11 b of the substrate 11 of the light emitting component 10 to form the first metal layer 31 (see FIG. 11B). . The fourth metal film 32 d and the third metal film 32 c are stacked in this order on the upper surface 20 a of the heat spreader 20 to form a second metal layer 32 (see FIG. 11B). At this time, the second metal film 31 b and the third metal film 32 c are formed of the same metal material. In the next bonding step of the metal film, if the first metal layer 31 and the second metal layer 32 are brought into contact under vacuum, the second metal film 31b and the third metal film 32c are bonded to form a single layer. One metal film 30b is formed, and as shown in FIG. 6B, a metal bonding layer 30 formed of three metal films 30a, 30b, and 30c is formed. On the other hand, when the first metal layer 31 and the second metal layer 32 are brought into contact with each other in the atmosphere, as shown in FIG. 6 (e), the metal composed of four metal films 31a, 31b, 32c, 33d Bonding layer 30 is formed.

  In the case of the metal bonding layer 30 as shown in FIG. 6E, the first metal film 31a and the fourth metal film 32d are formed of a metal material (Ag) having a high thermal conductivity, and the second metal is formed. By forming the film 31 b and the third metal film 32 c from a high metal material (Au) having a good bonding property, it is possible to obtain a metal bonding layer 30 having a high thermal conductivity and a good bonding property. In the extended portion 30x, the third metal film 32c of the second metal layer 32 is exposed to the surface. The Au that forms the third metal film 32c has a lower reflectance than the Ag that forms the fourth metal film 32d. Therefore, by making the third metal film 32c extremely thin (for example, 20 nm or less), the influence of the third metal film 32c on light reflection can be extremely reduced. Thus, the extension 30x can be used as a light reflecting member.

(About the metal bonding layer 30 of FIG. 6C and FIG. 6F)
First, the first metal film 31 e and the second metal film 31 f are stacked in this order on the lower surface 11 b of the substrate 11 of the light emitting component 10 to form the first metal layer 31 (see FIG. 11C). . The fourth metal film 32 h and the third metal film 32 g are stacked in this order on the upper surface 20 a of the heat spreader 20 to form a second metal layer 32 (see FIG. 11C). At this time, the second metal film 31 f and the third metal film 32 g are formed of the same metal material. In the next bonding step of the metal film, if the first metal layer 31 and the second metal layer 32 are brought into contact under vacuum, the second metal film 31 f and the third metal film 32 g are bonded to form a single film. It becomes one metal film 30e, and as shown in FIG. 6C, a metal bonding layer 30 composed of three metal films 30d, 30e, and 30f is formed. On the other hand, when the first metal layer 31 and the second metal layer 32 are brought into contact with each other in the atmosphere, as shown in FIG. 6F, the metal composed of four metal films 31e, 31f, 32g, and 33h Bonding layer 30 is formed.

  FIG. 12 shows the metal bonding layer 30 when the first metal layer 31 and the second metal layer 32 are stacked as shown in FIG. 11C and bonded in the atmosphere (that is, shown in FIG. 6F). It is a cross-sectional TEM image of metal joining layer 30). The first metal film 31 e in the first metal layer 31 and the fourth metal film 32 h in the second metal layer 32 are Cr films (film thickness 0.5 nm). The second metal film 31 f in the first metal layer 31 and the third metal film 32 g in the second metal layer 32 are Au films (film thickness 5 nm). The interface between the second metal film 31 f and the third metal film 32 g has not disappeared, and can be recognized as two layers.

The order of forming the first metal layer 31 and the second metal layer 32 can be changed. For example, the second metal layer 32 may be formed on the upper surface 20 a of the heat spreader 20 first, and the first metal layer 31 may be formed on the lower surface 11 b of the substrate 11 of the light emitting component 10 later.
Furthermore, when the first metal layer 31 and the second metal layer 32 are made of the same metal material, their film formation may be performed in the same step. That is, with the heat spreader 20 and the light emitting component 10 arranged side by side in the vacuum chamber 71, the sputtering target 72 is sputtered to form the first metal layer 31 and the second metal layer 32. It can be performed in the same step. Also in the case where the first metal layer 31 and the second metal layer 32 are formed of a plurality of metal films (for example, FIG. 11B, FIG. 11C, etc.), the layer configuration of the plurality of metal films, If the film thickness and the like of each metal film are the same, the film formation can be performed simultaneously in the same process.

  As shown in FIG. 5, when forming the metal bonding layer 30 on the entire upper surface 20a of the heat spreader 20, the edge 20e of the upper surface 20a of the heat spreader 20 is replaced with the holding member 74 shown in FIG. A retaining member 74 in the form of a non-pressing (i.e., completely covering the top surface 20a of the heat spreader 20) can be used. Further, when the heat spreader 20 can be stably disposed in the vacuum chamber 71, the second metal layer 32 may be formed on the heat spreader 20 without using the holding member 74.

  In the step of forming the first metal layer 31 and the second metal layer 32 described above, the film is formed by sputtering. However, not only the sputtering method but also a known film forming method (for example, a vacuum evaporation method, an ion plating method, etc.) can be used. The sputtering method, the CD method using a vacuum chamber, the vacuum evaporation method, and the ion plating method are advantageous in that the subsequent bonding step of the metal layers 31 and 32 under vacuum can be performed.

  Hereinafter, materials suitable for each component of the semiconductor device according to the first embodiment will be described.

(Substrate 11)
As the substrate 11, one having an insulating main body provided with metal wiring is used. Materials suitable for the substrate 11 include insulating materials such as glass epoxy, resin, ceramic and the like. In particular, a ceramic material excellent in heat dissipation is suitable. Examples of ceramic materials suitable for the substrate 11 include alumina, AlN, SiC, GaN, LTCC and the like. In particular, AlN having good processability and excellent thermal conductivity is particularly preferable.

(Semiconductor element 12)
Examples of the semiconductor element 12 suitable for the semiconductor device according to the present embodiment include a light emitting diode, a laser diode, a power semiconductor element and the like. Since these semiconductor elements 12 generate heat at the time of use, by using them in the semiconductor device according to the present embodiment excellent in heat dissipation, effects such as reduction of malfunction of the semiconductor elements and prolongation of life can be exhibited. .

(The heat dissipation member 20)
In the present specification, the heat dissipation member means a member having a thermal conductivity higher than that of the substrate on which the semiconductor element is mounted.
The heat dissipation member 20 includes a heat spreader, a heat sink, and the like. The heat dissipation member 20 is formed of a material having a high thermal conductivity in order to dissipate the heat generated in the semiconductor component 10 to the outside air. Moreover, in order to improve heat dissipation efficiency, protrusions, such as a fin, may be provided and a surface area may be increased, and metal materials with favorable castability, such as an alloy for die-casts, are also suitable. Specific materials that can be used include ADC12 (Al-Si-Cu based alloy for aluminum die casting), and metal materials such as Al and Cu.

(Metal bonding layer 30)
The metal bonding layer 30 as a whole is a member having a thermal conductivity higher than that of the heat dissipation member such as the heat spreader 20. Therefore, as a material suitable for the metal bonding layer 30, a metal material having a thermal conductivity higher than that of the material used for the heat dissipation member can be mentioned. Specifically, the metal bonding layer 30 preferably contains a metal selected from the group consisting of Au, Ag, Al, Cu, W, Si, Rh, Ru, and an alloy thereof, and is made of Au or an Au alloy. More preferably, it contains a metal. As used herein, the term "metal material" includes metals, metalloids and alloys.
As an example of a specific metal material, when using ADC12 (heat conductivity 96.3 W / mk) as a heat dissipation member, a metal material having a heat conductivity higher than that of ADC 12, for example, Au, Ag, Al, Cu, W , Si, Rh, Ru and the like are preferable. When Al (heat conductivity of 237 W · m ⁻¹ · K ⁻¹ ) is used as the heat dissipation member, a metal material having a heat conductivity higher than that of Al, such as Au, Ag, Cu or the like is preferable. When Cu (heat conductivity of 389 W · m ⁻¹ · K ⁻¹ ) is used as the heat dissipation member, a metal material having a heat conductivity higher than that of Cu, such as Ag, is preferable.

  As described above, in the case where the metal bonding layer 30 is formed of a plurality of metal films, a metal material having a thermal conductivity lower than that of the material used for the heat dissipation member is used for a part of the metal films. It can also be used. For example, when Cu is used as the heat dissipation member, the metal bonding layer 30 may be formed by laminating an Au thin film having a thermal conductivity lower than Cu on the surface of an Ag film having a thermal conductivity higher than Cu.

As mentioned above, although some embodiments according to the present invention have been illustrated, the present invention is not limited to the above-described embodiments, and it goes without saying that the present invention can be made arbitrary without departing from the scope of the present invention. Yes.
For example, although the semiconductor light emitting device is described as an example of the semiconductor device in the embodiment, it should be understood that the semiconductor device of the present invention includes various semiconductor devices such as a semiconductor memory and a power semiconductor. It is.
The disclosure content of the present specification may include the following aspects.
(Aspect 1)
A substrate on which a semiconductor element is mounted on the top surface;
A heat dissipation member,
And a metal bonding layer bonding the lower surface of the substrate and the upper surface of the heat dissipation member.
The area of the upper surface of the heat dissipation member is larger than the area of the lower surface of the substrate,
The metal bonding layer is in contact with the entire lower surface of the substrate and has a larger area than the lower surface of the substrate,
The thermal conductivity of the metal bonding layer is higher than the thermal conductivity of the heat dissipation member.
(Aspect 2)
The semiconductor device according to aspect 1, wherein the metal bonding layer covers the entire top surface of the heat dissipation member.
(Aspect 3)
The semiconductor device according to aspect 1 or 2, wherein the thickness of the metal bonding layer is 1 nm or more and 10 μm or less.
(Aspect 4)
The semiconductor device according to any one of Aspects 1 to 3, wherein the metal bonding layer is made of a metal material having a melting point of 350 ° C. or higher.
(Aspect 5)
Aspect 1. Any one of Aspects 1 to 4, wherein the metal bonding layer contains at least a metal selected from the group consisting of Au, Ag, Al, Cu, W, Si, Rh, Ru and an alloy thereof. Semiconductor device according to claim 1.
(Aspect 6)
6. The semiconductor device according to any one of aspects 1 to 5, wherein the metal bonding layer is made of Au or an Au alloy.
(Aspect 7)
The first aspect of the invention is characterized in that the metal bonding layer comprises a first metal layer positioned on the lower surface side of the substrate and a second metal layer positioned on the upper surface side of the heat dissipation member. The semiconductor device according to one.
(Aspect 8)
1) placing a semiconductor element on the upper surface of the substrate;
2) forming a first metal layer on the lower surface of the substrate;
3) forming a second metal layer having an area larger than the lower surface of the substrate on the upper surface of the heat dissipation member;
4) bringing the first metal layer and the second metal layer into contact with each other to bond them;
A method of manufacturing a semiconductor device, wherein a metal bonding layer composed of the first metal layer and the second metal layer is higher than the thermal conductivity of the heat dissipation member.
(Aspect 9)
The method according to aspect 8, wherein the metal bonding layer is made of a metal material having a melting point of 350 ° C. or higher.
(Aspect 10)
The method according to aspect 8 or 9, wherein in the step 2) and the step 3), the first metal layer and the second metal layer are deposited by sputtering.
(Aspect 11)
The first metal layer and the second metal layer are made of the same metal material,
Aspect 11. The method according to any one of aspects 8 to 10, wherein step 2) and step 3) are performed as the same step.
(Aspect 12)
The metal bonding layer contains at least a metal selected from the group consisting of Au, Ag, Al, Cu, W, Si, Rh, Ru and alloys thereof,
Aspect 12. The method according to any one of aspects 8 to 11, wherein step 2), step 3) and step 4) are performed in a vacuum chamber.
(Aspect 13)
The surface of the first metal layer and the surface of the second metal layer are made of Au or Au alloy,
Aspect 11. The method according to any one of aspects 8 to 11, wherein step 4) is performed in the atmosphere.

1, 2 Semiconductor devices (semiconductor light emitting devices)
10 Semiconductor parts (light emitting parts)
11 substrate 12 semiconductor element (light emitting element)
20 Heat dissipation member (heat spreader)
Reference Signs List 30 metal bonding layer 30 x extended portion 50 external heat dissipation member 70 sputtering apparatus

Claims (13)

A substrate on which a semiconductor element is mounted on the top surface;
A heat dissipation member,
And a metal bonding layer bonding the lower surface of the substrate and the upper surface of the heat dissipation member.
The area of the upper surface of the heat dissipation member is larger than the area of the lower surface of the substrate,
The metal bonding layer is in contact with the entire lower surface of the substrate and has a larger area than the lower surface of the substrate,
The thermal conductivity of the metal bonding layer is higher than the thermal conductivity of the heat dissipation member.   The semiconductor device according to claim 1, wherein the metal bonding layer covers the entire upper surface of the heat dissipation member.   The semiconductor device according to claim 1, wherein a thickness of the metal bonding layer is 1 nm or more and 10 μm or less.   The semiconductor device according to any one of claims 1 to 3, wherein the metal bonding layer is made of a metal material having a melting point of 350 ° C or more.   5. The metal bonding layer according to any one of claims 1 to 4, wherein the metal bonding layer contains at least a metal selected from the group consisting of Au, Ag, Al, Cu, W, Si, Rh, Ru and alloys thereof. The semiconductor device according to item 1.   The semiconductor device according to any one of claims 1 to 5, wherein the metal bonding layer is made of Au or an Au alloy.   The said metal joining layer consists of a 1st metal layer located in the lower surface side of the said board | substrate, and a 2nd metal layer located in the upper surface side of the said thermal radiation member. The semiconductor device according to claim 1. 1) placing a semiconductor element on the upper surface of the substrate;
2) forming a first metal layer on the lower surface of the substrate;
3) forming a second metal layer having an area larger than the lower surface of the substrate on the upper surface of the heat dissipation member;
4) bringing the first metal layer and the second metal layer into contact with each other to bond them;
A method of manufacturing a semiconductor device, wherein a metal bonding layer composed of the first metal layer and the second metal layer is higher than the thermal conductivity of the heat dissipation member.   The method according to claim 8, wherein the metal bonding layer is made of a metal material having a melting point of 350 ° C. or higher.   The method according to claim 8 or 9, wherein in the step 2) and the step 3), the first metal layer and the second metal layer are formed by sputtering. The first metal layer and the second metal layer are made of the same metal material,
The method according to any one of claims 8 to 10, wherein the step 2) and the step 3) are performed as the same step. The metal bonding layer contains at least a metal selected from the group consisting of Au, Ag, Al, Cu, W, Si, Rh, Ru and alloys thereof,
The method according to any one of claims 8 to 11, wherein the steps 2), 3) and 4) are performed in a vacuum chamber. The surface of the first metal layer and the surface of the second metal layer are made of Au or Au alloy,
The method according to any one of claims 8 to 11, wherein step 4) is performed in the atmosphere.

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