Semiconductor light-emitting device, method for manufacturing semiconductor light-emitting device, and bonded structure

Abstract

To provide a semiconductor light-emitting device in which a light-emitting element is hardly peeled off from a sub-mount substrate even when thermal stress is applied, and accuracy of a position and a direction of the light-emitting element is high.SOLUTION: The metal layer on the lower surface of the submount substrate has a lower surface and a side surface covered with the covering layer. The coating layer includes a first coating layer made of a material higher in hardness than the metal forming the metal layer, and a second coating layer covering the first coating layer and made of a material lower in hardness than the first coating layer. The first covering layer and the second covering layer cover the entire lower face and side faces of the metal layer, and the lower face of the second covering layer covering the lower face of the metal layer is directly bonded to the upper face of the mounting board. The covering layer has a convex portion protruding from the side surface below the side surface of the metal layer, and the lower surface of the convex portion forms a continuous surface with the lower surface of the covering layer covering the lower surface of the metal layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a semiconductor light emitting device having a structure in which a submount substrate on which a semiconductor light emitting element is mounted is directly bonded to a metal substrate. [Background technology]

[0002] Conventionally, semiconductor light-emitting devices have been known in which a submount substrate, to which a light-emitting element is die-bonded, is mounted on a metal mounting substrate with excellent thermal conductivity. Submount substrates are typically ceramic substrates such as aluminum nitride, with metal layers on the top and bottom surfaces. Metal mounting substrates have a wiring pattern formed on the surface of the metal substrate via an insulating layer. When mounting the submount substrate on the metal mounting substrate, an adhesive with high thermal conductivity (solder, metal bumps, or a heat-conducting adhesive with a metal filler) is used.

[0003] Meanwhile, ultrasonic bonding techniques are known that directly bond two metal materials by ultrasonically vibrating one of the two metal materials without using adhesive, as disclosed in Patent Documents 1 and 2. Patent Document 1 discloses a method and structure for bonding a submount substrate to a metal mounting substrate by ultrasonic bonding. Patent Document 2 discloses a bonding method in which metal plates are pressure-bonded while being deformed using a method called mechanical clinch bonding, and then ultrasonic vibrations are applied to the bonded portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2024-002209 [Patent Document 2] Japanese Patent Application Publication No. 2020-116600 Summary of the Invention [Problem to be solved by the invention]

[0005] When the bonding surfaces bonded by the ultrasonic bonding method of Patent Document 1 are warped due to thermal stress in the submount substrate or light emitting element, cracks may develop around the periphery of the bonding interface, potentially causing separation.

[0006] The bonding method of Patent Document 2, which combines mechanical clinch bonding and ultrasonic bonding, uses a large force to deform the metal and press it into a recess, making it difficult to uniformly deform the metal plate and to bond the light emitting element while maintaining the height position and optical axis direction with high precision. Furthermore, applying a large force to the submount substrate of the light emitting element may impair the reliability of the light emitting element.

[0007] An object of the present invention is to provide a semiconductor light emitting device in which the light emitting element is unlikely to peel off from the submount substrate even when thermal stress is applied, and in which the position and orientation of the light emitting element are highly accurate. [Means for solving the problem]

[0008] To achieve the above object, the semiconductor light-emitting device of the present invention comprises a submount substrate, a light-emitting element bonded to the upper surface of the submount substrate, and a metal mounting substrate on the upper surface of which the submount substrate is mounted. The submount substrate has a metal layer on its lower surface. The lower surface and side surfaces of the metal layer are covered with a coating layer. The coating layer on the lower surface of the metal layer is directly bonded to the upper surface of the mounting substrate. The coating layer includes a first coating layer made of a material harder than the metal constituting the metal layer, and a second coating layer covering the first coating layer and made of a material harder than the first coating layer. The first coating layer and the second coating layer entirely cover the lower surface and side surfaces of the metal layer, and the lower surface of the second coating layer covering the lower surface of the metal layer is directly bonded to the upper surface of the mounting substrate. The coating layer has a convex portion protruding from the side surface below the side surface of the metal layer, and the lower surface of the convex portion forms a surface continuous with the lower surface of the coating layer covering the lower surface of the metal layer. [Effects of the Invention]

[0009] In the semiconductor light-emitting device of the present invention, the convex portion formed by the coating layer below the side surface of the metal layer provides a large contact area with the mounting substrate, making it difficult for the light-emitting element to peel off from the submount substrate even when thermal stress is applied. Furthermore, since strong bonding is possible even with only a small amount of deformation of the metal layer, the precision of the position and orientation of the light-emitting element can be improved. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a semiconductor light emitting device 1 according to an embodiment. [Figure 2] 1 is a partially enlarged cross-sectional view of a semiconductor light emitting device 1 according to an embodiment. [Figure 3] (a-1) and (a-2) are enlarged cross-sectional views and cross-sectional photographs of a portion of the semiconductor light-emitting device 1 before bonding, and (b-1) and (b-2) are enlarged cross-sectional views and cross-sectional photographs of a portion of the semiconductor light-emitting device 1 after bonding. [Figure 4] 1A is a partially enlarged cross-sectional view of the semiconductor light-emitting device 1 before bonding, and FIG. 1B is a partially enlarged cross-sectional view of the semiconductor light-emitting device 1 after bonding. [Figure 5] (a) is an enlarged cross-sectional view and a photograph of the cross-section of a portion of a semiconductor light-emitting device 1 in which a portion of the side of a protrusion 25 on the side of a metal layer 23 is buried in a metal substrate 31; (b) is an enlarged cross-sectional view and a photograph of the cross-section of a portion of a semiconductor light-emitting device 1 in which the entire side of a protrusion 25 on the side of a metal layer 23 is buried in a metal substrate 31. [Figure 6] (a) and (c) are photographs and a cross-section of a portion of a semiconductor light-emitting device 1 in which part of the side of the protrusion 25 on the side of the metal layer 23 is embedded in the metal substrate 31, and (b) is a cross-section of the joint between the side of the metal layer 23 and the metal substrate 31 in a comparative example. [Figure 7] 2 is a flow chart showing a manufacturing process of the semiconductor light emitting device 1 according to the embodiment. [Figure 8] 3(a) to 3(f) are cross-sectional views showing the manufacturing process of the semiconductor light emitting device 1 according to the embodiment. [Figure 9] 2A to 2C are cross-sectional views showing a manufacturing process of the semiconductor light emitting device 1 according to the embodiment. [Figure 10]10(a) and 10(b) are cross-sectional views of a sample of a semiconductor light-emitting device according to a modified example of the present embodiment. [Figure 11] 10 is a graph showing bonding conditions (static pressure and energy in the ultrasonic bonding process) for samples of semiconductor light emitting devices manufactured in Examples, and images of the bonded surfaces of the manufactured samples. [Figure 12] 6(a) and 6(b) are cross-sectional photographs of a sample of a semiconductor light-emitting device manufactured in an example. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described below.

[0012] The configuration of a semiconductor light-emitting device 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view of the semiconductor light-emitting device 1. Figs. 2, 3(b-1), (b-2), and 4(b) are partial enlarged views of the semiconductor light-emitting device 1 in Fig. 1. Figs. 3(a-1), (a-2), and 4(a) are partial enlarged views of the semiconductor light-emitting device 1 before bonding.

[0013] The semiconductor light emitting device 1 has a configuration in which the light emitting element 10 is bonded onto a submount substrate 20, and the lower surface of the submount substrate 20 is directly bonded to a mounting substrate 30 by ultrasonic bonding.

[0014] In this embodiment, for convenience, the surface of the submount substrate 20 on which the light-emitting element 10 is disposed is referred to as the upper surface, and the surface of the submount substrate 20 on which the metal substrate 31 is disposed is referred to as the lower surface. However, when using the semiconductor light-emitting device, the semiconductor light-emitting device is not limited to being disposed with the side on which the light-emitting element 10 is disposed facing upward. Of course, the semiconductor light-emitting device can also be disposed with the light-emitting element 10 facing downward or to the side.

[0015] The submount substrate 20 includes a ceramic substrate 21 serving as a base, a pair of wiring patterns 22 disposed on the upper surface of the ceramic substrate 21, and a metal layer 23 disposed over the entire lower surface of the ceramic substrate 21.

[0016] The mounting substrate 30 has an insulating layer 32 provided on part of the surface of a metal substrate 31 serving as a base, and a circuit pattern 33 mounted thereon. The insulating layer 32 is not provided in the region where the submount substrate 20 is to be disposed.

[0017] The submount substrate 20 will now be described.

[0018] The ceramic substrate 21 of the submount substrate 20 is made of a material with excellent thermal conductivity (for example, AlN, SiN, Al2O3, etc.).

[0019] The metal layer 23 of the submount substrate 20 preferably has excellent thermal conductivity and excellent adhesion to the ceramic substrate 21. For example, the metal layer 23 is made of Cu.

[0020] The light emitting element 10 is die-bonded onto the wiring pattern 22 of the submount substrate 20 using an element bonding material 11. The element bonding material 11 may be a conductive paste, a solder bonding material, or a eutectic bonding material such as AuSn.

[0021] 2, 3(b-1), (b-2), and 4(b), the lower and side surfaces of the metal layer 23 on the lower surface of the submount substrate 20 are covered with a covering layer 24. The covering layer 24 includes a first covering layer 24a, a second covering layer 24c, and an intermediate layer 24b disposed between the first covering layer 24a and the second covering layer 24c.

[0022] The first covering layer 24a, the intermediate layer 24b, and the second covering layer 24c cover the entire lower surface and side surfaces of the metal layer 23.

[0023] The lower surface of the second covering layer 24c that covers the lower surface of the metal layer 23 is directly bonded to the upper surface of the mounting substrate 30 by ultrasonic bonding, without an intervening bonding layer or the like.

[0024] The first coating layer 24a is made of a material harder than the metal constituting the metal layer 23. The second coating layer 24c coats the first coating layer 24a and is made of a material harder than the first coating layer 24a. For example, for the metal layer 23 made of Cu, the first coating layer 24a can be a Ni layer, the second coating layer 24c can be a layer made of any of Au, Cu, and Al, and the intermediate layer can be a layer made of Pd.

[0025] In this way, by disposing the first coating layer 24a, which is harder than the metal layer 23, on the side and bottom surfaces of the metal layer 23, which has a substantially rectangular parallelepiped shape before bonding (FIGS. 3(a-1), (a-2), and 4(a)), during ultrasonic bonding, the first coating layer 24a prevents the metal layer 23 from being crushed in the thickness direction, and the coating layer 24 deforms around the lower edges of the side surfaces, forming protrusions 25 (FIGS. 3(b-1), (b-2), and 4(b)). The protrusions 25 are formed only on the lower edges of the side surfaces of the coating layer 24, and are formed below one-third of the height of the side surfaces of the coating layer 24 in the thickness direction. However, the positions above the protrusions 25 on the side surfaces of the coating layer 24, i.e., the region of at least one-third of the thickness of the side surfaces of the coating layer 24, maintain the same shape as before ultrasonic bonding. For example, the region above the protrusion 25 on the side surface of the coating layer 24 maintains a shape perpendicular to the lower surface of the ceramic substrate 21 .

[0026] That is, the covering layer 24 covering the side surfaces of the metal layer 23 has a main plane that is perpendicular or nearly perpendicular to the lower surface of the submount substrate 20 in the region above the protrusion 25 .

[0027] The second covering layer 24c has low hardness and conforms to the first covering layer 24a before and after deformation, covering the surface of the first covering layer 24a. Therefore, the second covering layer 24c comes into contact with the metal substrate 31 of the mounting board 30, enabling ultrasonic bonding.

[0028] The intermediate layer 24b prevents the first coating layer 24a and the second coating layer 24c from diffusing into each other.

[0029] As described above, the coating layer 24 has a protrusion 25 that protrudes from the side surface toward the outer periphery at the lower end of the side surface of the metal layer 23. The protrusion 25 is formed by deformation of the coating layer 24 during ultrasonic bonding. The lower surface 25a of the protrusion 25 is smoothly continuous with the lower surface 24d of the coating layer 24 that covers the lower surface of the metal layer 23.

[0030] The thickness of the first covering layer 24a is designed taking into consideration the amount of energy applied during ultrasonic bonding so that deformation of the metal layer 23 is minimized and protrusions 25 are formed during ultrasonic bonding. The second covering layer 24c is designed to a thickness that allows ultrasonic bonding to the metal substrate 31. It is preferable to take the surface roughness of the metal substrate 31 into consideration when designing. The intermediate layer 24b should have a thickness that prevents diffusion and peeling so that the first covering layer 24a and the second covering layer 24c can perform their respective functions. It is also possible to configure the structure without the intermediate layer 24b.

[0031] The mounting substrate 30 will now be described.

[0032] A metal with excellent thermal conductivity (for example, an Al substrate or a Cu substrate) is used for the metal substrate 31 of the mounting substrate 30. The upper surface of the metal substrate 31 is exposed in the region where the submount substrate 20 is mounted.

[0033] An insulating layer 32 is disposed on the upper surface of the mounting substrate 30 in an area where the circuit pattern 33 is to be disposed. The insulating layer 32 is made of a material that can insulate the circuit pattern 33 from the metal substrate 31 at a predetermined withstand voltage. The material of the insulating layer 32 has a thermal conductivity that is much lower than that of metals. For example, a fibrous reinforcing material called prepreg is uniformly impregnated with a thermosetting resin such as epoxy, and the semi-cured material is processed into a desired pattern and mounted on the metal substrate 31, and then the cured insulating layer 32 is used. The circuit pattern 33 is made of a metal with low electrical resistance (e.g., Cu).

[0034] The covering layer 24 of the metal layer 23 of the submount substrate 20 is bonded to the mounting substrate 30. As shown in Figures 3(b-2), 4(b), 5(a), (b), and 6(a), (c), around the bonding area, it is preferable that the upper surface of the metal substrate 31 of the mounting substrate 30 is located at a position higher than the lower surfaces 25a of the protrusions 25 of the covering layer 24, and that the upper surface of the metal substrate 31 covers at least a part of the side surfaces of the protrusions 25. In other words, it is preferable that the metal substrate 31 of the mounting substrate 30 is raised around the bonding surface of the metal layer 23 of the submount substrate 20.

[0035] 5(b), the upper surface of the metal substrate 31 of the mounting substrate 30 may be positioned higher than the upper end of the convex portion 25 of the covering layer 24, and the upper surface of the metal substrate 31 may cover the entire convex portion 25.

[0036] 3(b-2) and 4(b), a deformed portion 23a of a part (the peripheral portion of the lower end of the side surface) of the metal layer 23 protrudes into the inside of the convex portion 25 of the coating layer 24. The protruding deformed portion 23a of the metal layer 23 is covered by the coating layer 24 of the convex portion 25. The side surface of the metal layer 23 has a vertical or nearly vertical shape above the deformed portion 23a.

[0037] It is not necessary for the part 23a of the metal layer 23 to protrude into the inside of the protrusion 25 of the coating layer 24, and the protrusion 25 may be formed by the coating layer 24 alone.

[0038] As described above, in the semiconductor light-emitting device of this embodiment, a convex portion 25 that protrudes outward from the lower end of the side surface of the metal layer 23 due to deformation of the coating layer 24 is formed, thereby increasing the bonding area between the metal substrate 31 and the coating layer 24 and increasing the bonding strength compared to the comparative example shown in Figure 6(b) in which the convex portion 25 is not formed.

[0039] Furthermore, in the region around the metal layer 23, the upper surface of the metal substrate 31 of the mounting board 30 is positioned above the bonding surface, and as shown in FIGS. 3(b-2), 4(b), 5(a), (b), and 6(a), (c), the protrusions 25 of the coating layer 24 protruding from the side surfaces of the metal layer 23 are embedded in the metal substrate 31 of the mounting board 30. The bonding surface is not flat, but rather a three-dimensional curved surface whose shape also changes in the thickness direction of the metal substrate 31. As a result, unlike the structure of the comparative example shown in FIG. 6(b), which has only a component in the main plane direction of the metal substrate 31, the bonding surface of the protrusions 25 also has a vertical component (a bonding surface whose shape changes in the depth direction). Therefore, even if a force is applied in the thickness direction of the metal substrate 31 to peel the metal layer 23 and the coating layer 24, as shown in FIG. 6(c), the bonding surface is less likely to peel, and the bonding strength between the coating layer 24 of the metal layer 23 and the outer periphery can be increased.

[0040] As a result, in the semiconductor light-emitting device of this embodiment, even if warping occurs in the metal substrate 31 or the metal layer 23 due to thermal stress, cracks are less likely to occur at the outer periphery of the bonding surface, and high peel resistance against thermal stress can be achieved.

[0041] Furthermore, since the protrusions 25 protrude in the outer periphery direction and the bonding area is increased, the heat from the semiconductor light emitting element can be spread and conducted to the metal substrate 31 more efficiently than in a structure without the protrusions 25.

[0042] In particular, by using an embedded structure in which at least a portion of the side surface of the protrusion 25 is in contact with the metal substrate 31, as shown in Figures 3(b-2), 4(b), 5(a), (b), and 6(a), (c), a new path for heat conduction from the side surface of the metal layer 23 to the metal substrate 31 via the protrusion 25 can be secured.

[0043] This allows heat from the light emitting element 10 to be efficiently conducted to the metal substrate 31, and reduces stress caused by warping of the metal substrate 31 and the metal layer 23 due to thermal stress.

[0044] Furthermore, in the semiconductor light-emitting device of this embodiment, the bottom and side surfaces of the metal layer 23 are covered with a first covering layer 24a that is harder than the metal layer 23, and deformation of the metal layer 23 itself due to ultrasonic bonding is minimized, while convex portions 25 of the same shape can be provided on the covering layer 24 all around the outer periphery of the bonding surface by circular vibration using elliptical complex vibration bonding or the like. As a result, convex portions 25 are provided on the outer periphery of the bonding surface where stress in the direction of peeling the metal layer 23 from the metal substrate 31 is concentrated.

[0045] Therefore, the shape of the metal layer 23 itself does not deform significantly due to ultrasonic bonding, so the thickness of the metal layer 23 can be maintained before and after bonding, and any variations in the thickness of the metal layer 23 can also be maintained before and after bonding. Therefore, variations in the height position of the light emitting element 10 and the tilt of the optical axis between products after bonding can be suppressed.

[0046] In addition, the coating layer 24 not only functions as heat conduction and peel prevention at the bonding surface of the convex portion 25 as described above, but also serves to prevent corrosion of the metal layer 23 because it covers the entire upper and lower surfaces of the metal layer 23.

[0047] Although a ceramic substrate 21 is used here, it is also possible to use a sapphire substrate, a silicon (Si) substrate, a gallium nitride (GaN) substrate, a carbon nitride (SiC) substrate, or the like.

[0048] <Manufacturing process of semiconductor light emitting devices> Next, a method for manufacturing the semiconductor light emitting device 1 of this embodiment will be described.

[0049] Fig. 7 is a flow diagram showing the manufacturing process, and Fig. 8(a) to (f) are cross-sectional views showing the manufacturing process. Fig. 9 is a view for explaining how the fixing jig 50 is placed from above.

[0050] (Step S1) First, as shown in FIG. 8(a), the light emitting element 10 is mounted (die-bonded) on the wiring pattern 22 on the upper surface of the submount substrate 20 using AuSn eutectic as the element bonding material 11.

[0051] (Step S2) 8(b), the mounting substrate 30 is mounted on a fixing jig 50. The submount substrate 20 is set on the mounting substrate 30 so that the upper surface of the light emitting element 10 faces upward.

[0052] (Step S3) 8(c) and 9, an ultrasonic tool 60 is brought into contact with the submount substrate 20. A recess is formed in the ultrasonic tool 60, and the ultrasonic tool 60 is placed over the light-emitting element 10 so that the light-emitting element 10 is positioned within the recess. This allows the ultrasonic tool to come into contact with the submount substrate 20 without coming into contact with the light-emitting element 10.

[0053] While applying pressure in a direction that presses the submount substrate 20 against the mounting substrate 30 using the ultrasonic tool 60 , ultrasonic energy is applied to the submount substrate 20 and the mounting substrate 30 through the ultrasonic tool 60 .

[0054] As a result, pressure and ultrasonic vibrations from the ultrasonic tool 60 are applied to the metal substrate 31 of the mounting substrate 30 and the metal layer 23 and coating layer 24 of the submount substrate 20. Friction / plastic flow occurs between the surface of the metal substrate 31 and the second coating layer 24c in contact, expelling the oxide film on the metal surface and exposing a new metal surface. The metal substrate 31 and the second coating layer 24c deform around the contact point between the exposed metals, increasing the contact area, and the entire contact surface is solid-state bonded by atomic forces. Unlike fusion bonding, this solid-state bonding is performed in a solid state near room temperature, far below the melting point of the metal materials.

[0055] At this time, since the side and underside of the metal layer 23 are covered with the first coating layer 24a, which is harder than the metal layer 23, deformation of the metal layer 23 is kept to a minimum, making it easier to maintain the thickness of the metal layer 23.

[0056] On the other hand, at the peripheral portion of the lower end of the side surface of the metal layer 23, the coating layer 24 or a part of the metal layer 23 and the coating layer 24 are deformed to form a protrusion 25.

[0057] 3(b-2), 4(b), 5(a), (b), and 6(a), (c), the pressure force of the ultrasonic tool 60 and the energy of the ultrasonic waves are adjusted so that at least a portion of the side surface of the protrusion 25 is embedded in the metal substrate 31. Specifically, the ultrasonic energy is set so that only the peripheral portion at the lower end of the side surface of the metal layer 23 is deformed to form the protrusion 25.

[0058] The vibration mode of the ultrasonic tool 60 may be linear vibration, but ultrasonic composite vibration (circular or elliptical vibration in which torsional vibration is added to linear vibration) vibrates in a circular manner, making it easier to apply pressure to the outer periphery of the joining surfaces, forming a convex portion 25 and enabling the outer periphery of the joining surfaces to be joined more firmly.

[0059] (Step S4) Next, the joined mounting substrate 30 and submount substrate 20 are removed from the fixing jig 50. Then, as shown in Fig. 8(d), the upper electrode of the light-emitting element 10 is connected to one of the wiring patterns 22 on the submount substrate 20 by a bonding wire 71. Furthermore, the wiring pattern 22 on the submount substrate 20 is connected to the circuit pattern 33 on the mounting substrate 30 by a bonding wire 72.

[0060] (Step S5) Next, as shown in FIG. 8( e ), a phosphor plate 80 is mounted on the upper surface of the light emitting element 10 , and a light reflective frame 81 is placed on the mounting substrate 30 a predetermined distance away from the submount substrate 20 .

[0061] (Step S6) Finally, as shown in Figure 8(f), sealing resin 82 containing dispersed light-reflective filler is filled inside the frame body 81 so as to embed the light-emitting element 10 and the submount substrate 20, except for the upper surface of the phosphor plate 80, and then cured.

[0062] In this manner, the semiconductor light emitting device 1 can be manufactured.

[0063] Steps S5 and S6 may be performed as needed.

[0064] Furthermore, any surface unevenness structure can be provided on the surface of the ultrasonic tool that contacts the mounting substrate 30 and on the surface of the first step portion 52 of the fixing jig 50 that contacts the submount substrate 20. This allows ultrasonic energy to be applied efficiently to the bonding surface 40. In this case, the unevenness structure is transferred to the surface of the submount substrate 20 or mounting substrate 30 that the unevenness structure contacts.

[0065] Although the semiconductor light-emitting device and its manufacturing method of this embodiment have been described with respect to a single light-emitting element 10, a plurality of light-emitting elements may be arranged on the submount substrate. In this case, when setting the light-emitting element in the fixing jig in step S2, a plurality of light-emitting elements may be accommodated in a single cavity, or alternatively, light-emitting elements may be accommodated in a plurality of cavities as appropriate.

[0066] <<Modifications>> A semiconductor light emitting device 1 according to a modification of this embodiment will be described.

[0067] In the above embodiment, an example has been described in which a portion of the side surface of the convex portion 25 of the coating layer 24 at the lower end of the side surface of the metal layer 23 and the upper end of the convex portion 25 are embedded in the metal substrate 31 of the mounting substrate 30, but this embodiment is not limited to the above configuration.

[0068] For example, as shown in FIG. 10(a), the metal layer 23 on the upper part of the protrusion 25 may be embedded in the metal substrate 31 of the mounting substrate 30 up to the vertical or nearly vertical side surface.

[0069] 10(b), not only the vertical or nearly vertical side surfaces of the metal layer 23 of the submount substrate 20 but also the side surfaces of the ceramic substrate 21 may be embedded in the metal substrate 31 of the mounting substrate 30.

[0070] In this way, by covering the vertical or nearly vertical side surfaces of the metal layer 23, or even the side surfaces of the ceramic substrate 21, with the metal substrate 31, the peel strength and heat dissipation properties of the bonding surface between the metal layer 23 and the metal substrate 31 can be further improved.

[0071] The technology of the semiconductor light emitting device of this embodiment and the modified example can be used in a lamp light source unit and a white light source module. [Example]

[0072] As an example, a semiconductor light emitting device 1 was manufactured by the manufacturing method of the embodiment described above in FIG.

[0073] The size of the submount substrate 20 was 3 mm x 4 mm x 0.48 mm. The ceramic substrate 21 was made of AlN and had a thickness of 380 μm, the metal layer 23 was made of Cu and had a thickness of 50 μm, and the coating layer 24 had a first coating layer 24a which was a Ni layer and had a thickness of 5 μm, an intermediate layer 24b which was a Pd layer and had a thickness of 0.1 μm, and a second coating layer 24c which was an Au layer and had a thickness of 0.1 μm.

[0074] The material of the metal substrate 31 of the mounting substrate 30 was Al (aluminum A1100 or A5052).

[0075] As shown in FIG. 11, multiple samples of semiconductor light-emitting devices 1 were manufactured by varying the static pressure applied from the ultrasonic tool 60 during ultrasonic bonding between 300 N and 800 N and the amplitude AMPL (the input current ratio corresponding to the vibration amplitude, where the amplitude generated at the maximum input current value is 100%) between 15%, 20%, and 25%. The bonding time was 1 second in all cases. The bonding conditions were set by the amplitude (AMPL) [%], static pressure [N], and bonding time [sec], but the ultrasonic energy value (J) calculated by converting these conditions using the ultrasonic bonding device was also evaluated as a bonding condition. The ultrasonic energy value during the manufacture of multiple samples of semiconductor light-emitting devices 1 was 130 J to 330 J.

[0076] The bonding surfaces of samples of the manufactured semiconductor light-emitting device 1 were photographed using an acoustic microscope (C-SAM: Constant-depth mode Scanning Acoustic Microscope) to determine whether there were any cavities. The graph in Figure 11 shows images of each sample photographed with the acoustic microscope. In each image, the black parts are the bonding areas, and the white parts are the cavities.

[0077] 11, when the ultrasonic energy was approximately 200 J or more, there were no cavities on the joining surface, and the entire surface was joined. At the same time, when the ultrasonic energy was 200 J or more, the coating layer 24 protruded outward from the lower peripheral edge of the side surface of the metal layer 23, forming a convex portion 25 that was embedded in the metal substrate 31. Furthermore, the convex portion 25 was formed only on the lower end of the side surface of the coating layer 24, and the upper portion of the side surface of the coating layer 24 maintained the same shape as before joining, maintaining a shape that was approximately perpendicular to the bottom surface of the ceramic substrate 21.

[0078] Figure 12(a) shows a cross-sectional photograph of a sample welded under the conditions of static pressure 350N, energy 200J, amplitude 20%, and welding time 1 second. Figure 12(b) shows a cross-sectional photograph of a sample welded under the conditions of static pressure 500N, energy 260J, amplitude 20%, and welding time 1 second.

[0079] As shown in Figures 12(a) and (b), the shape of the convex portion 25 changes slightly depending on the bonding conditions, but it was confirmed that under all conditions the side surface of the metal layer 23 above the convex portion 25 remains vertical, and the convex portion 25 is formed only at the lower end of the side surface. [Explanation of symbols]

[0080] 10 Light-emitting element 11 Element bonding material 20 Submount substrate 21 Ceramic substrate 22 Wiring Pattern 24 Covering layer 24a 1st coating layer 24b Middle class 24c 2nd coating layer 23 Metal layer 30 Mounting board 31 Metal substrate 32 Insulating layer 33 Circuit Pattern 60 Ultrasonic Tools 61 Cavity 71 Bonding Wire 72 Bonding Wire 80 Phosphor Plate 81 Frame 82 Sealing resin

Claims

1. a submount substrate, a light emitting element bonded to an upper surface of the submount substrate, and a metal mounting substrate on an upper surface of which the submount substrate is mounted; the submount substrate has a metal layer on its bottom surface; the metal layer has a lower surface and a side surface covered with a covering layer; a coating layer on a lower surface of the metal layer directly joined to an upper surface of the mounting substrate; the coating layer includes a first coating layer made of a material having a higher hardness than the metal constituting the metal layer, and a second coating layer that coats the first coating layer and is made of a material having a lower hardness than the first coating layer; the first covering layer and the second covering layer cover the entire lower surface and side surfaces of the metal layer, and the lower surface of the second covering layer covering the lower surface of the metal layer is directly bonded to the upper surface of the mounting substrate; A semiconductor light-emitting device characterized in that the coating layer has a convex portion at the lower end of the side surface of the metal layer that protrudes outward from the side surface, and the lower surface of the convex portion has a surface that is continuous with the lower surface of the coating layer that covers the lower surface of the metal layer.

2. 2. The semiconductor light emitting device according to claim 1, A semiconductor light-emitting device characterized in that the upper surface of the mounting substrate is located at a higher position than the lower surface of the convex portion around the metal layer, and the upper surface of the mounting substrate covers at least a portion of the side surface of the convex portion.

3. 3. The semiconductor light emitting device according to claim 2, The semiconductor light emitting device is characterized in that the upper surface of the mounting substrate is located at a position higher than the upper end of the convex portion, and the upper surface of the mounting substrate covers the entire convex portion.

4. 2. The semiconductor light emitting device according to claim 1, The semiconductor light-emitting device according to claim 1, wherein the covering layer covering the side surfaces of the metal layer has a main surface that is perpendicular or nearly perpendicular to the lower surface of the submount substrate in the region above the protrusion.

5. 2. The semiconductor light emitting device according to claim 1, A semiconductor light-emitting device characterized in that a portion of the metal layer protrudes inside the convex portion of the covering layer, and the protruding metal layer is entirely covered by the covering layer of the convex portion.

6. 2. The semiconductor light emitting device according to claim 1, the metal layer is made of Cu, the first coating layer is made of Ni, The second coating layer is made of any one of Au, Cu, and Al. A semiconductor light emitting device characterized by:

7. 2. The semiconductor light emitting device according to claim 1, A third coating layer is disposed as an intermediate layer between the first coating layer and the second coating layer. A semiconductor light emitting device characterized by:

8. 8. The semiconductor light emitting device according to claim 7, The intermediate layer is made of Pd A semiconductor light emitting device characterized by:

9. a placement step of placing a submount substrate having a light emitting element mounted on an upper surface thereof and a metal layer on a lower surface thereof, and a metal mounting substrate on the lower surface side of the submount substrate; a bonding step of bonding the metal layer of the submount substrate to the mounting substrate by pressing an ultrasonic tool against the upper surface of the submount substrate and ultrasonically vibrating the tool; In the disposing step, the submount substrate is one in which the lower surface and side surfaces of the metal layer are covered with a covering layer, and the covering layer includes a first covering layer made of a material having a harder property than the metal constituting the metal layer, and a second covering layer covering the first covering layer and made of a material having a harder property than the first covering layer, In the joining step, the ultrasonic tool is pressed and ultrasonically vibrated so that the coating layer protrudes from the side surface below the side surface of the metal layer to form a convex portion, and the lower surface of the convex portion forms a surface continuous with the lower surface of the coating layer that covers the lower surface of the metal layer.

10. A method for manufacturing a semiconductor light emitting device, comprising:

10. a ceramic substrate having a metal layer formed on a lower surface thereof, and a metal substrate bonded to the surface of the ceramic substrate on which the metal layer is formed, the metal layer has a lower surface and a side surface covered with a covering layer; the coating layer on the lower surface of the metal layer is directly bonded to the upper surface of the metal substrate; the coating layer includes a first coating layer made of a material having a higher hardness than the metal constituting the metal layer, and a second coating layer that coats the first coating layer and is made of a material having a lower hardness than the first coating layer; the first coating layer and the second coating layer cover the entire lower surface and side surfaces of the metal layer, and the lower surface of the second coating layer covering the lower surface of the metal layer is directly bonded to the upper surface of the metal substrate; A joint structure characterized in that the coating layer has a convex portion protruding from the side surface below the side surface of the metal layer, and the lower surface of the convex portion forms a surface continuous with the lower surface of the coating layer that covers the lower surface of the metal layer.

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