JP6908859B2 - Semiconductor devices and methods for manufacturing semiconductor devices - Google Patents

Description

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

In semiconductor components including high-power semiconductor elements (for example, semiconductor light emitting elements for automobiles), it is important to efficiently dissipate heat generated by the semiconductor elements during use. Therefore, a semiconductor component is attached to a heat radiating member formed of a material having high thermal conductivity to improve heat radiating property.
In semiconductor parts, a ceramic substrate having excellent thermal conductivity can be used as a substrate on which a semiconductor element is placed (Patent Documents 1 to 3). When attaching the semiconductor component to the heat radiating member, the ceramic substrate of the semiconductor component is joined to the heat radiating member. As a joining method at that time, for example, it is known to use solder (Patent Documents 1 and 2) and silver paste (Patent Document 3).
Further, as another method for joining a plurality of members, a room temperature joining method is known (Patent Document 4). In the room temperature joining method, a metal film is formed on the joining surface of each member under vacuum, and the plurality of members can be joined by bringing the metal films into contact with each other. By using this normal temperature joining method for joining a semiconductor component and a heat radiating member, it is considered that heat radiating performance, heat diffusion performance and the like are improved.

Japanese Unexamined Patent Publication No. 2009-194275 Japanese Unexamined Patent Publication No. 2013-055218 Japanese Unexamined Patent Publication No. 2010-166019 Japanese Unexamined Patent Publication No. 2008-207221

In the joining methods disclosed in Patent Documents 1 to 3, the thermal conductivity of the solder or silver paste cannot be said to be sufficiently high, and the heat dissipation efficiency from the semiconductor component to the heat radiating member is not sufficient.
In the room temperature joining method disclosed in Patent Document 4, since the semiconductor component and the heat radiating member are joined by a metal material having high thermal conductivity, the heat radiating efficiency from the semiconductor component to the heat radiating member is compared with Patent Documents 1 to 3. Is expensive. However, further improvement in heat dissipation efficiency is required due to an increase in the amount of heat generated as the output of the semiconductor element increases.
Therefore, an object of the embodiment of the present invention is to provide a semiconductor device having high heat dissipation efficiency from a semiconductor component to a heat radiating member and a method for manufacturing the same.

The semiconductor device according to the embodiment of the present invention includes a substrate on which a semiconductor element is placed on an upper surface, a heat radiating member, and a metal bonding layer that joins a lower surface of the substrate and an upper surface of the radiating member, and dissipates heat. 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 an area larger than the lower surface of the substrate. The thermal conductivity is higher than the thermal conductivity of the heat radiating member.

Further, the method for manufacturing a semiconductor device according to the embodiment of the present invention is described.
1) The process of placing the semiconductor element on the upper surface of the substrate and
2) A step of forming a first metal layer on the lower surface of the substrate and
3) A step of forming a second metal layer having an area larger than the lower surface of the substrate on the upper surface of the heat radiating member, and
4) Including a step of bringing the first metal layer into contact with the second metal layer and joining them.
The metal bonding layer composed of the first metal layer and the second metal layer is characterized in that the heat conductivity is higher than that of the heat radiating member.

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

FIG. 1 is a schematic perspective view showing a state in which the semiconductor device according to the first embodiment of the present invention is mounted on an external heat radiating member. FIG. 2 is a partially enlarged top view of the semiconductor device and the external heat radiating member shown in FIG. FIG. 3 is a schematic cross-sectional view of the semiconductor device in line AA of FIG. FIG. 4 is a partially enlarged cross-sectional view for explaining a heat dissipation path of the semiconductor device according to the first embodiment. FIG. 5 is a cross-sectional view showing a modified example of the semiconductor device according to the first embodiment. 6 (a) to 6 (f) are partially 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 modification of the semiconductor device according to the embodiment of the present invention. 8 (a) to 8 (c) are cross-sectional views for explaining a manufacturing process of a semiconductor device. 9 (a) and 9 (b) are cross-sectional views for explaining a manufacturing process of a semiconductor device. 10 (a) and 10 (b) are cross-sectional views for explaining a manufacturing process of a semiconductor device. FIG. 11 is a partially enlarged cross-sectional view showing a mode of laminating the metal film for forming the metal bonding layer shown 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 with reference to the drawings. In the following description, terms indicating a specific direction or position (for example, "top", "bottom", "right", "left", and other terms including those terms) are used as necessary. .. The use of these terms is to facilitate understanding of the invention with reference to the drawings, and the meaning of these terms does not limit the technical scope of the invention. Further, the parts having the same reference numerals appearing in a plurality of drawings indicate the same parts or members.

<Embodiment 1>
In the present embodiment, a semiconductor device (that is, a semiconductor light emitting device) in which the semiconductor element is a light emitting element will be described as an example.
FIGS. 1 to 3 show a semiconductor device (semiconductor light emitting device) 1 according to the present embodiment and an external heat radiating member (heat sink) 50 on which the semiconductor device 1 is mounted. 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 11a thereof. As the substrate 11, a main body of an insulating material having good heat dissipation and provided with metal wiring for energizing the light emitting element 12 can be used. In this embodiment, a ceramic substrate using a ceramic material for the main body is used.

The heat spreader 20 is a plate-shaped member for radiating heat generated by the light emitting element 12, and the heat spread efficiency can be improved by the heat spreader 20 alone or in combination with a heat sink. 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 radiating member to which the light emitting component 10 is attached, but the heat sink 50 may be used as the heat radiating member. In that case, the light emitting component 10 is attached directly to the heat sink 50 without the heat spreader 20.

The upper surface 20a of the heat spreader 20 is provided with a metal bonding layer 30 that covers at least a part of the upper surface 20a. 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 joins the lower surface 11b of the substrate 11 of the light emitting component 10 to the upper surface 20a of the heat spreader 20. The area of the metal bonding layer 30 is larger than the area of the lower surface 11b of the substrate 11 of the light emitting component 10. When the light emitting component 10 is arranged on the metal bonding layer 30, the light emitting component 10 is arranged so that the entire lower surface 11b of the substrate 11 is contained in the region where the metal bonding layer 30 is formed. As a result, the entire lower surface 11b of the substrate 11 comes into contact with 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.
Since the metal bonding layer 30 has the above-mentioned characteristics, the heat dissipation efficiency of the semiconductor light emitting device 1 can be improved.

The reason for the improvement in heat dissipation efficiency is not clear, but it is thought that it is due to the following mechanism.
As shown in FIG. 4, the heat generated by the light emitting element 12 spreads in the substrate 11 and is transmitted to the metal bonding layer 30, and further transferred to the heat spreader 20. The heat tends to concentrate in the region 20u directly below the substrate 11 of the heat spreader 20. In order to increase the heat dissipation efficiency, it is effective to promote heat conduction to a region (outer edge region 20x) outside the region 20u directly below.

In the semiconductor light emitting device 1 according to the present embodiment, the area of the metal bonding layer 30 is larger than the area of the entire lower surface 11b of the substrate 11, so that when the light emitting component 10 is arranged on the metal bonding layer 30, the metal bonding layer 30 At least a part of the outer periphery extends to the outside of the substrate 11 (this extending portion is referred to as "extended portion 30x").
The heat dissipation path from the substrate 11 (for example, point P ₁ ) to the outer edge region 20x (for example, point P _{2 ) of the heat spreader 20 includes a first heat dissipation path T 1} that does not pass through the outer extension portion 30x of the metal bonding layer 30 and an outer extension. 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 , the metal bonding layer 30 passes through the metal bonding layer 30 in the thickness direction (−z direction) and proceeds to the region 20u directly below the heat spreader 20 (path t _1a ). Thereafter, it proceeds to the heat spreader 20 in the lateral direction (-x direction), and reaches the point _{P 2} (path _t 1b).
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 Then, it reaches the extension portion 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).

Comparing these two heat dissipation paths, the path t _{1a of} the first heat dissipation path T1 and the path t _{2b of the second} heat dissipation path T 2 both point vertically downward (-z) in the heat spreader 20 by approximately the same distance. Since it goes in the direction), there is no difference in the ease of heat conduction (heat conductivity).
On the other hand, the path t _{1b of} the first heat dissipation path T1 and the path t _{2a of the second} heat dissipation path T 2 travel in the lateral direction (−x direction) by approximately the same distance, but the path t _1b is the metal bonding layer 30. _{Since the path t 2a} passes through the inside and passes through the heat spreader 20, the thermal conductivity is different. As described above, since the thermal conductivity of the metal bonding layer 30 is higher than that of the heat spreader 20, the path t _2a passing through the metal bonding layer 30 is more heat than the _{path t 1b} passing through the heat spreader 20. Has excellent conductivity.
That is, the second heat dissipation path T ₂ has higher heat dissipation efficiency than the first heat dissipation path T _1. In the semiconductor light emitting device 1 according to the present embodiment, since the metal bonding layer 30 includes the outer extension portion 30x 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 until 20 of the outer edge region 20x, the second heat radiation path T ₂ is formed with high heat dissipation efficiency. As a result, 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 a range excluding the edge 20e of the upper surface 20a of the heat spreader 20 (that is, the edge 20e of the upper surface 20a 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 20a of the heat spreader 20 is covered with the metal bonding layer 30. As a result, the area of the outer extension 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 dissipation efficiency of the heat dissipation 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. Considering 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). Further, the metal bonding layer 30 may be formed by laminating a plurality of metal films (see FIGS. 6 (b) to 6 (f)). The metal bonding layer 30 including the plurality of metal films further includes a metal bonding layer 30 containing an odd number of metal films (FIGS. 6 (b) to 6 (c)) and a metal bonding layer 30 containing an even number of metal films. (FIGS. 6 (d) to 6 (f)).

FIG. 6B 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 side of the heat spreader 20, and one thin metal film 30b is provided between them. Is provided. In this form, the two-layer metal films 30a and 30c are formed of a metal material having high thermal conductivity (for example, Ag), and the one-layer metal film 30b is formed of a metal material having good bondability (for example, Au etc.). ), It is possible to obtain a metal bonding layer 30 having high thermal conductivity and good bonding properties.

FIG. 6C shows a metal bonding layer 30 also composed of three metal films 30d, 30e, and 30f. In this example, two thin metal films 30d and 30f are provided on the lower surface 11b side of the substrate 11 and the upper surface 20a side of the heat spreader 20, and one thick metal film 30e is provided between them. Is provided. In this embodiment, the two-layer metal films 30d and 30f are formed of a metal material having good bondability with the substrate 11 and the heat spreader 20 (for example, Cr), and the one-layer metal film 30e is a metal having high thermal conductivity. By forming from a material (for example, Ag), a metal bonding layer 30 having high thermal conductivity and good bonding properties can be obtained.

FIG. 6D shows a metal bonding layer 30 composed of two metal films. In this example, the metal film on the lower surface 11b side of the substrate 11 is referred to as the first metal layer 31, and the metal film on the upper surface 20a side of the heat spreader 20 is referred to as the second metal layer 32. In this form, both the first metal layer 31 and the second metal layer 32 are formed from a metal material (for example, Au) having relatively good thermal conductivity and bondability, thereby having thermal conductivity. A metal bonding layer 30 having relatively good bondability can be obtained.

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, fourth metal film 32d) are provided on the lower surface 11b side of the substrate 11 and the upper surface 20a side of the heat spreader 20, and these are provided. Two thin metal films (second metal film 31b, third metal film 32c) are provided between them. In this embodiment, the first metal film 31a and the fourth metal film 32d are formed from 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 32c from a metal material having good bondability and high oxidation resistance (for example, Au), a metal bond layer 30 having high thermal conductivity and good bondability can be obtained.
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 from two metal films (first metal film 31a, second metal film 31b). The second metal layer 32 formed and provided on the upper surface 20a side of the heat spreader 20 is formed from the two metal films (third metal film 32c, fourth metal film 32d), and then the second metal. It can be formed by joining the film 31b and the third metal film 32c.

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

The main 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. In addition, it is due to the difference in manufacturing method. Although 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 joining under vacuum. On the other hand, the metal bonding layer 30 as shown in FIGS. 6D to 6F has a first metal layer 31 formed on the lower surface 11b of the substrate 11 and a second metal bonding layer 30 formed on the upper surface 20a side of the heat spreader 20. It can be formed by contacting and joining the metal layer 32 in the atmosphere (that is, in an oxygen-containing atmosphere).

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. It means the thermal conductivity of. When the metal bonding layer 30 is formed from 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, it is defined that "the thermal conductivity of the metal bonding layer 30 is higher than the thermal conductivity of the heat spreader 20". This regulation intends 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 provision is not intended that all the metal materials contained in the metal bonding layer 30 have a thermal conductivity higher than that 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 lower than that of the heat spreader 20, the other metal film has a thermal conductivity higher than that of the heat spreader 20. When the metal bonding layer 30 as a whole has a higher thermal conductivity than the heat spreader 20 due to being formed from the 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 in satisfying the regulations 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 obtained 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 is determined. By using it, the thermal resistance Rm = R1-R2 of the metal bonding layer 30 can be obtained. Further, in the present specification, the thickness t ₃₀ (m) of the metal bonding layer 30 is defined by the thermal resistance Rm (k / W) of the metal bonding layer 30 and the total area A (m ² ) of the metal bonding layer 30. By dividing (calculation formula: t ₃₀ / (Rm × A)), the thermal conductivity (W · m ^-1 · K ^-1 ) of the entire metal bonding layer 30 can be obtained.

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 a metal multilayer film obtained by laminating a metal layer made of a metal α _{having a thermal conductivity T α and a metal layer made of a metal β having a thermal conductivity T β} at a film thickness ratio a: b is as follows. It can be obtained by the equation (1).
T = T _α × T _β × (a + b) / (a × T _β + b × T _α ) ・ ・ ・ (1)

The above equation (1) was obtained by the following procedure.
A formula for calculating the thermal conductivity T of a metal multilayer film in which a metal layer composed of a metal α having a thermal conductivity T _{α and a metal layer composed of a metal β having a thermal conductivity T β is laminated at a film thickness ratio a: b.} think about.
The thermal resistance Rm of the entire metal multilayer film is Rm = R _α + R _{β using the thermal resistance R α} of the metal α and the thermal resistance R _β of the metal β. 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, by substituting (1-1) for (1-2) above, T = t ₃₀ / (t _α / T _α + t _β / T _β ), and in summary, T = T _α × T _β × It becomes t ₃₀ / (t _α × T _β + t _β × T _α).
Here, if the _{film thickness a is substituted for t α} , the film thickness _{b is substituted for t β,} and the film thickness a + b is substituted for _{t 30, then}
T = T _α × T _β × (a + b) / (a × T _β + b × T _α ) ・ ・ ・ (1).

As will be described later, when the metal bonding layer 30 has a step (see FIG. 10), the thickness t _{32 of the extension portion 30x is defined as “thickness t 30} of the metal bonding layer 30”, and the metal including the extension portion 30x. The area of the bonding layer 30 is defined as "total area A". The thermal conductivity calculated by the above formula (1) corresponds to the thermal conductivity of the second metal layer 32 in FIGS. 11 (b) and 11 (c).

Substituting a specific numerical value into the equation (1), the thermal conductivity of the metal bonding layer 30 is obtained. The thermal conductivity of the metal bonding layer 30 laminated in three layers as shown in FIG. 6B is obtained. The two layers (metal films 30a, 30c) are formed from Ag (thermal conductivity 427W ・ m ^-1 , K ^-1 ), and one layer (metal film 30b) between them is Au (thermal conductivity 427W ・ m -1 ・ K -1). It is formed from 315W ・ m ^-1・ K ^-1). The ratio of the total film thickness of the metal films 30a and 30c to the film thickness of the metal film 30b is 5: 1 (that is, the film thickness of Ag is 5 times thicker than Au).
The approximate value of the thermal conductivity T of the metal bonding layer 30 is
T = 315 x 427 x 6 / (1 x 427 + 5 x 315) = 403.1 W ・ m ^-1・ K ^-1
Will be. That is, the metal bonding layer 30 has a higher thermal conductivity than ^{Cu (398W · m -1} · K ^-1). Therefore, the metal bonding layer 30 made of Ag and Au can be used in combination with the heat radiating member made of Cu.

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

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

Referring to FIG. 3 again, in the semiconductor light emitting device 1 according to the present embodiment, the light emitting component 10 includes a wavelength conversion member 13 and a light reflective molded body 15 in addition to the light emitting element 12 and the substrate 11. You may. The wavelength conversion member 13 is a member for wavelength-converting the light from the light emitting element 12, and for example, a plate-shaped member containing a phosphor that converts blue light emission into yellow light can be used. The light-reflecting molded body 15 is formed of a material that reflects light (for example, a white resin material containing a light-reflecting substance 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-reflecting molded body 15, it is possible to reflect the light traveling in the lateral direction (x direction) and suppress the leakage of the light in the lateral direction. can.

Further, 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 a light emitting element 12 mounted on the upper surface 11a of the substrate 11, a wavelength conversion layer 213 covering the upper surface and side surfaces of the light emitting element 12, and a resin molded body 214 covering the light emitting element 12 and the wavelength conversion layer 213. , Including. The wavelength conversion layer 213 can be formed from, for example, a material containing a phosphor that converts blue light emission into yellow light. The surface of the resin molded body 214 is formed in a hemispherical shape 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. 8 to 10.

<Step 1) Preparation of light emitting component 10>
The light emitting element 12 is placed on the upper surface 11a of the substrate 11 provided with the wiring (see FIG. 8A). In addition, one or a plurality of light emitting elements 12 (three in FIG. 8A) can be mounted. When the light emitting component 10 includes the wavelength conversion member 13 and the light-reflecting 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-reflecting molded body 15 (see FIG. 8C).

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

<Step 3) Formation of the second metal layer 32>
A second metal layer 32 is formed on the upper surface 20a of the heat spreader 20 by a sputtering method (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 larger than the area of the lower surface 11b of the substrate 11.
First, the heat spreader 20 is arranged in the vacuum chamber 71 of the sputtering apparatus 70. At this time, the position and orientation of the heat spreader 20 are adjusted so that the upper surface 20a 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 arranged directly below the sputtering target 72 so that the upper surface 20a of the heat spreader 20 faces upward.
A holding member 74 for holding the heat spreader 20 in a predetermined position and direction may be used. In this figure, since the holding member 74 presses a part of the upper surface 20a of the heat spreader 20 (for example, the edge portion 20e), the edge portion 20e of the upper surface 20a pressed by the holding member 74 has a second metal layer. 32 is not formed.

<Step 4) Joining steps 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 are formed at room temperature. (See FIG. 10 (a)). The first metal layer 31 and the second metal layer 32, which have been placed under vacuum as they are after being formed in the vacuum chamber 71, have high surface energies, and atomic diffusion occurs only by bringing them into contact with each other at room temperature. Can be joined to each other. By this bonding, the boundary line between the first metal layer 31 and the second metal layer 32 is almost eliminated, and the metal bonding layer 30 composed of, for example, one metal film as shown in FIG. 6A is formed. Is formed.
When the first metal layer 31 and the second metal layer 32 are brought into contact with each other, the lower surface 11b of the substrate 11 of the light emitting component 10 is the second metal layer 32 formed on the upper surface 20a of the heat spreader 20. The light emitting component 10 and the heat spreader 20 are aligned so as to be arranged at a desired position.

When the first metal layer 31 and the second metal layer 32 are made of a metal material having excellent oxidation resistance and a large diffusion coefficient (for example, Au or Au alloy), those metal layers 31, 32 can also be joined 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 from the vacuum chamber 71 into the atmosphere. Then, in the atmosphere, at room temperature, 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 are brought into contact with each other. Thereby, the first metal layer 31 and the second metal layer 32 can be joined to each other. However, since the surface energy of the first metal layer 31 and the second metal layer 32 decreases due to being taken out into the atmosphere, the boundary line between the first metal layer 31 and the second metal layer 32 Does not disappear. Therefore, for example, as shown in FIG. 6D, the metal bonding layer 30 is formed in a state where the first metal layer 31 and the second metal layer 32 can be distinguished from each other.

Summarizing the effects of joining under each atmosphere, joining the metal layers 31 and 32 under vacuum can increase the joining force between the metal layers 31 and 32.
On the other hand, when the metal layers 31 and 32 are joined in the atmosphere, it is easy to perform an operation of aligning the light emitting component 10 and the heat spreader 20 at the time of joining. Therefore, it becomes easy to improve the positional accuracy of the light emitting component 10 with respect to the heat spreader 20, and it can be expected that the defective product occurrence rate is suppressed and the yield is improved.

By steps 1) to 4), a semiconductor light emitting device 1 in which the light emitting component 10 and the heat spreader 20 are joined by a metal bonding layer 30 can be obtained (see FIG. 10B). The metal bonding layer 30 formed by the above 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) be. 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 it is the outer extension portion 30x of the metal bonding layer 30 that mainly contributes to heat dissipation, the thickness of the outer extension portion 30x (that is, the film thickness t ₃₂ ) is treated as _{the film thickness t 30} of the metal bonding layer 30. I decided.

Further, the metal bonding layer 30 shown in FIGS. 6 (a) to 6 (f) described above includes a step 2) a step of forming the first metal layer 31, and a step 3) a step of forming the second metal layer 32. And step 4) It can be formed by changing the conditions of the joining step of the metal layers 31 and 32 as follows.

(Regarding the metal bonding layer 30 of FIGS. 6 (a) and 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 from the same metal material. In the next metal film joining step, if the first metal layer 31 and the second metal layer 32 are brought into contact with each other under vacuum, as shown in FIG. 6A, a metal composed of a single metal film is formed. The 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 formed. It is formed.

(Regarding the metal bonding layer 30 of FIGS. 6 (b) and 6 (e))
First, the first metal film 31a and the second metal film 31b are laminated in this order on the lower surface 11b of the substrate 11 of the light emitting component 10 to form the first metal layer 31 (see FIG. 11B). .. A fourth metal film 32d and a third metal film 32c are laminated in this order on the upper surface 20a of the heat spreader 20 to form a second metal layer 32 (see FIG. 11B). At this time, the second metal film 31b and the third metal film 32c are formed from the same metal material. In the next metal film joining step, if the first metal layer 31 and the second metal layer 32 are brought into contact with each other under vacuum, the second metal film 31b and the third metal film 32c are joined and simply joined. It becomes one metal film 30b, and as shown in FIG. 6B, a metal bonding layer 30 composed 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), a metal composed of four metal films 31a, 31b, 32c and 33d. The bonding layer 30 is formed.

In the case of the metal bonding layer 30 as shown in FIG. 6 (e), the first metal film 31a and the fourth metal film 32d are formed from a metal material (Ag) having high thermal conductivity, and the second metal is formed. By forming the film 31b and the third metal film 32c from a metal material (Au) having good bondability, a metal bonding layer 30 having high thermal conductivity and good bondability can be obtained. In the extension portion 30x, the third metal film 32c of the second metal layer 32 is exposed on the surface. Au forming the third metal film 32c has a lower reflectance than Ag forming 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. As a result, the extension portion 30x can be used as a light reflecting member.

(Regarding the metal bonding layer 30 of FIGS. 6 (c) and 6 (f))
First, the first metal film 31e and the second metal film 31f are laminated in this order on the lower surface 11b of the substrate 11 of the light emitting component 10 to form the first metal layer 31 (see FIG. 11C). .. A fourth metal film 32h and a third metal film 32g are laminated in this order on the upper surface 20a of the heat spreader 20 to form a second metal layer 32 (see FIG. 11C). At this time, the second metal film 31f and the third metal film 32g are formed from the same metal material. In the next metal film joining step, if the first metal layer 31 and the second metal layer 32 are brought into contact with each other under vacuum, the second metal film 31f and the third metal film 32g are joined and simply joined. 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. 6 (f), a metal composed of four metal films 31e, 31f, 32g and 33h. The bonding layer 30 is formed.

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

The order in which the first metal layer 31 and the second metal layer 32 are formed can be changed. For example, the second metal layer 32 may be formed on the upper surface 20a of the heat spreader 20 first, and the first metal layer 31 may be formed later on the lower surface 11b of the substrate 11 of the light emitting component 10.
Further, when the first metal layer 31 and the second metal layer 32 are made of the same metal material, the film formation thereof may be performed in the same step. That is, the heat spreader 20 and the light emitting component 10 are arranged side by side in the vacuum chamber 71, and 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 process. When the first metal layer 31 and the second metal layer 32 are formed of a plurality of metal films (for example, FIGS. 11 (b), 11 (c), etc.), the layer structure of the plurality of metal films, If the film thickness of each metal film is the same, the film formation can be performed simultaneously in the same process.

As shown in FIG. 5, when the metal bonding layer 30 is formed 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 used instead of the holding member 74 shown in FIG. 9B. A holding member 74 that does not press (that is, does not cover the upper surface 20a of the heat spreader 20 at all) can be used. Further, when the heat spreader 20 can be stably arranged 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, a film is formed by a sputtering method. However, the film forming method is not limited to the sputtering method, and a known film forming method (for example, vacuum vapor deposition method, ion plating method, etc.) can also be used. The sputtering method, the CD method using a vacuum chamber, the vacuum deposition method, and the ion plating method are advantageous in that the subsequent joining steps of the metal layers 31 and 32 can be performed under vacuum.

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

(Board 11)
As the substrate 11, a substrate 11 having an insulating main body provided with metal wiring is used. Examples of materials suitable for the substrate 11 include insulating materials such as glass epoxy, resin, and ceramic. In particular, a ceramic material having excellent heat dissipation is preferable. Examples of the ceramic material suitable for the substrate 11 include alumina, AlN, SiC, GaN, and LTCC. In particular, AlN, which has good workability 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 during use, by using them in the semiconductor device according to the present embodiment having excellent heat dissipation, it is possible to achieve effects such as reduction of malfunction of the semiconductor elements and extension of life. ..

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

(Metal bonding layer 30)
The metal bonding layer 30 as a whole is a member having a higher thermal conductivity than a heat radiating member such as a heat spreader 20. Therefore, examples of the material suitable for the metal bonding layer 30 include a metal material having a higher thermal conductivity than the material used for the heat radiating member. 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 alloys thereof, and is made of Au or Au alloy. More preferably, it contains a metal. As used herein, the term "metal material" includes metals, metalloids, and alloys.
As a specific example of a metal material, when ADC12 (thermal conductivity 96.3 W / mk) is used as a heat dissipation member, a metal material having a higher thermal conductivity than ADC12, for example, Au, Ag, Al, Cu, W , Si, Rh, Ru and the like are suitable. When Al (thermal conductivity 237 W, m ^-1 , K ^-1 ) is used as the heat radiating member, a metal material having a higher thermal conductivity than Al, for example, Au, Ag, Cu, or the like is suitable. When Cu (thermal conductivity 389 W, m ^-1 , K ^-1 ) is used as the heat radiating member, a metal material having a higher thermal conductivity than Cu, for example, Ag, is suitable.

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

Although some embodiments of the present invention have been illustrated above, it goes without saying that the present invention is not limited to the above-described embodiments and can be arbitrary as long as it does not deviate from the gist of the present invention. stomach.
For example, in the embodiment, a semiconductor light emitting device is described as an example of the semiconductor device, but 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. Is.
The disclosure of the present specification may include the following aspects.
(Aspect 1)
A substrate on which a semiconductor element is placed on the upper surface,
Heat dissipation member and
A metal bonding layer for joining the lower surface of the substrate and the upper surface of the heat radiating member is included.
The area of the upper surface of the heat radiating 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.
A semiconductor device characterized in that the thermal conductivity of the metal bonding layer is higher than the thermal conductivity of the heat radiating member.
(Aspect 2)
The semiconductor device according to aspect 1, wherein the metal bonding layer covers the entire surface of the upper surface of the heat radiating 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)
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 alloys thereof. The semiconductor device described in 1.
(Aspect 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)
One of aspects 1 to 6, wherein the metal bonding layer is composed of a first metal layer located on the lower surface side of the substrate and a second metal layer located on the upper surface side of the heat radiating member. The semiconductor device according to one.
(Aspect 8)
1) The process of placing the semiconductor element on the upper surface of the substrate and
2) A step of forming a first metal layer on the lower surface of the substrate and
3) A step of forming a second metal layer having an area larger than the lower surface of the substrate on the upper surface of the heat radiating member, and
4) Including a step of bringing the first metal layer into contact with the second metal layer and joining them.
A method for manufacturing a semiconductor device, characterized in that the metal bonding layer composed of the first metal layer and the second metal layer has a higher thermal conductivity than that of the heat radiating member.
(Aspect 9)
The production 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 production method according to aspect 8 or 9, wherein in the steps 2) and 3), the first metal layer and the second metal layer are formed into a film by a sputtering method.
(Aspect 11)
The first metal layer and the second metal layer are made of the same metal material.
The manufacturing method according to any one of aspects 8 to 10, wherein the steps 2) and 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.
The manufacturing method according to any one of aspects 8 to 11, wherein the steps 2), 3) and 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 an Au alloy.
The production method according to any one of aspects 8 to 11, wherein the step 4) is performed in the atmosphere.

1, 2 Semiconductor device (semiconductor light emitting device)
10 Semiconductor parts (light emitting parts)
11 Substrate 12 Semiconductor element (light emitting element)
20 Heat dissipation member (heat spreader)
30 Metal joint layer 30 x Outer part 50 External heat dissipation member 70 Sputtering device

Claims (14)

A substrate on which a semiconductor light emitting element is placed on the upper surface,
A light-reflecting molded body that covers the side surface of the semiconductor light emitting device,
Heat dissipation member and
A metal bonding layer that joins the lower surface of the substrate and the upper surface of the heat radiating member ,
A wavelength conversion member for converting light from the semiconductor light emitting element is included on the semiconductor light emitting element .
The area of the upper surface of the heat radiating 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 rather higher than the thermal conductivity of the heat radiating member,
The light-reflecting molded body is a semiconductor light emitting device that further covers the side surface of the wavelength conversion member. The semiconductor light emitting device according to claim 1, wherein the light-reflecting molded body is formed of a white resin material containing titanium oxide particles. The semiconductor light emitting device according to claim 1 or 2, wherein the metal bonding layer covers the entire surface of the upper surface of the heat radiating member. The semiconductor light emitting device according to any one of claims 1 to 3, wherein the thickness of the metal bonding layer is 1 nm or more and 10 μm or less. The semiconductor light emitting device according to any one of claims 1 to 4, wherein the metal bonding layer is made of a metal material having a melting point of 350 ° C. or higher. Any of claims 1 to 5, 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 light emitting device according to item 1. The semiconductor light emitting device according to any one of claims 1 to 6, wherein the metal bonding layer is made of Au or an Au alloy. Any of claims 1 to 7, wherein the metal bonding layer is composed of a first metal layer located on the lower surface side of the substrate and a second metal layer located on the upper surface side of the heat radiating member. The semiconductor light emitting device according to item 1. 1) The process of placing the semiconductor light emitting element on the upper surface of the substrate and
2) A step of fixing a wavelength conversion member for converting light from the semiconductor light emitting element on the semiconductor light emitting element, and
3 ) A step of forming a light-reflecting molded body on the side surface of the semiconductor light emitting element and the side surface of the wavelength conversion member, and
4 ) A step of forming a first metal layer on the lower surface of the substrate, and
5 ) A step of forming a second metal layer having an area larger than the lower surface of the substrate on the upper surface of the heat radiating member, and
6 ) Including a step of bringing the first metal layer into contact with the second metal layer and joining them.
A method for manufacturing a semiconductor light emitting device, wherein the metal bonding layer composed of the first metal layer and the second metal layer has a higher thermal conductivity than the heat conductivity of the heat radiating member. The production method according to claim 9, wherein the metal bonding layer is made of a metal material having a melting point of 350 ° C. or higher. The production method according to claim 9 or 10, wherein in steps 4 ) and 5 ), the first metal layer and the second metal layer are formed by a sputtering method. The first metal layer and the second metal layer are made of the same metal material.
The manufacturing method according to any one of claims 9 to 11, wherein the steps 4 ) and 5) 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 manufacturing method according to any one of claims 9 to 12, wherein the steps 4 ), 5 ) and 6) 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 an Au alloy.
The production method according to any one of claims 9 to 12, wherein the step 6) is performed in the atmosphere.

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