Surface-emitting laser module and method for manufacturing same

Abstract

In the present invention, a surface-emitting laser chip (1) has an upper surface, a portion of which forms a light-emitting surface (2). An electrode (4) is provided on the upper surface of the surface-emitting laser chip (1) so as to surround the light-emitting surface (2). A lead frame (6) has an opening (6a) provided at a position facing the light-emitting surface (2), and a bonding part (6b) provided around the opening (6a). A bonding material (7) bonds the electrode (4) and the bonding part (6b). A through-hole (6c) that vertically penetrates the lead frame (6) is provided to the bonding part (6b).

Description

Surface-emitting laser module and manufacturing method thereof

[0001] The present disclosure relates to a surface-emitting laser module and a method for manufacturing the same.

[0002] A surface-emitting laser chip emits light in a vertical direction from its light-emitting surface (see, for example, Patent Document 1). Conventionally, wire bonding has been used to provide electrical wiring on the light-emitting surface side of a surface-emitting laser chip. In recent years, the use of lead frames has been considered to increase the yield of products.

[0003] Japanese Patent Publication No. 11-266058

[0004] When multiple chips are bonded to a lead frame via a bonding material, the distance between each chip and the lead frame varies, which causes the bonding material to be crushed in chips that are close to the lead frame and flow out onto the light-emitting surface, obstructing the light-emitting surface.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a surface-emitting laser module and a manufacturing method thereof that can prevent bonding material from flowing out onto the light-emitting surface.

[0006] The surface-emitting laser module according to the present disclosure comprises a surface-emitting laser chip, part of whose upper surface is a light-emitting surface, an electrode provided on the upper surface of the surface-emitting laser chip so as to surround the light-emitting surface, a lead frame having an opening provided at a position opposite the light-emitting surface and a joint provided around the opening, and a bonding material for bonding the electrode and the joint, wherein a through-hole passing vertically through the lead frame is provided in the joint.

[0007] In the present disclosure, through holes are provided in the bonding portions of the lead frames, and excess bonding material flows into the narrow through holes by capillary action, preventing the bonding material from flowing out onto the light emitting surface.

[0008] 1 is a plan view showing a surface-emitting laser chip according to a first embodiment. FIG. 2 is a cross-sectional view showing a surface-emitting laser chip according to the first embodiment. FIG. 3 is a cross-sectional view showing a surface-emitting laser module according to the first embodiment. FIG. 4 is a cross-sectional view showing a manufacturing process of the surface-emitting laser module according to the first embodiment. FIG. 5 is a cross-sectional view showing a manufacturing process of the surface-emitting laser module according to the first embodiment. FIG. 6 is a cross-sectional view showing a manufacturing process of the surface-emitting laser module according to the first embodiment. FIG. 7 is a cross-sectional view showing a modified example of the manufacturing process of the surface-emitting laser module according to the first embodiment. FIG. 8 is a cross-sectional view showing a modified example of the manufacturing process of the surface-emitting laser module according to the first embodiment. FIG. 9 is a cross-sectional view showing a modified example of the manufacturing process of the surface-emitting laser module according to the first embodiment. FIG. 10 is a plan view showing a modified example of the surface-emitting laser chip according to the first embodiment. FIG. 11 is a cross-sectional view showing a modified example of the surface-emitting laser module according to the first embodiment. Fig. 1 is a cross-sectional view showing a surface-emitting laser module according to embodiment 5. Fig. 2 is a plan view showing a surface-emitting laser module according to embodiment 6. Fig. 3 is a cross-sectional view showing a surface-emitting laser module according to embodiment 6. Fig. 4 is a plan view showing a surface-emitting laser chip according to embodiment 7. Fig. 5 is a cross-sectional view showing a surface-emitting laser chip according to embodiment 7. Fig. 6 is a cross-sectional view showing a surface-emitting laser module according to embodiment 7.

[0009] A surface-emitting laser module and a method for manufacturing the same according to an embodiment will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0010] First Embodiment Fig. 1 is a plan view showing a surface-emitting laser chip according to a first embodiment. Fig. 2 is a cross-sectional view showing the surface-emitting laser chip according to the first embodiment. The surface-emitting laser chip 1 has a semiconductor substrate 1a of a first conductivity type, and an active layer 1b and a semiconductor layer 1c of a second conductivity type stacked in this order on the substrate 1a. For example, the first conductivity type is n-type, and the second conductivity type is p-type.

[0011] A part of the upper surface of the surface-emitting laser chip 1 is a light-emitting surface 2. The light-emitting surface 2 is covered with an insulating film 3. An electrode 4 is provided on the upper surface of the surface-emitting laser chip 1 so as to surround the light-emitting surface 2. An electrode 5 is provided on the lower surface of the surface-emitting laser chip 1. When a voltage is applied between the electrodes 4 and 5, light is generated in the active layer 1b. The generated light is emitted from the light-emitting surface 2 in a direction perpendicular to the upper surface of the surface-emitting laser chip 1.

[0012] Fig. 3 is a plan view showing the surface-emitting laser module according to the first embodiment. Fig. 4 is a cross-sectional view showing the surface-emitting laser module according to the first embodiment. The lead frame 6 has an opening 6a provided at a position facing the light emitting surface 2 and a joint portion 6b provided around the opening 6a. A joint material 7 joins the upper surface of the electrode 4 of the surface-emitting laser chip 1 to the lower surface of the joint portion 6b of the lead frame 6. The lead frame 6 is made of a metal such as copper. The joint material 7 is, for example, solder.

[0013] A through hole 6c that passes through the lead frame 6 from top to bottom is provided in the bonding portion 6b of the lead frame 6. A plurality of small circular through holes 6c are provided to surround the opening 6a in a plan view. A portion of the bonding material 7 flows into the through holes 6c.

[0014] Next, a method for manufacturing the surface-emitting laser module according to this embodiment will be described. Figures 5 to 7 are cross-sectional views showing the manufacturing process of the surface-emitting laser module according to embodiment 1. First, an electrode 4 is formed on the upper surface of the surface-emitting laser chip 1 so as to surround the light-emitting surface 2 of the surface-emitting laser chip 1. An opening 6a is formed in the lead frame 6, and a through-hole 6c that passes through the lead frame 6 from top to bottom is formed in the joint 6b around the opening 6a.

[0015] Next, as shown in FIG. 5 , a bonding material 7 is applied onto the electrode 4. Next, as shown in FIG. 6 , the opening 6 a of the lead frame 6 is positioned opposite the light-emitting surface 2 of the surface-emitting laser chip 1, and the bonding portion 6 b of the lead frame 6 is placed on the bonding material 7. Next, as shown in FIG. 7 , the bonding material 7 is melted by heating, and the electrode 4 and the bonding portion 6 b are bonded by the molten bonding material 7. At this time, the opening 6 a forms a wider space on the light-emitting surface 2 side, while the through-hole 6 c forms a narrow space. Therefore, excess bonding material 7 flows into the narrow through-hole 6 c by capillary action and does not flow out onto the light-emitting surface 2. In particular, when the bonding material 7 is solder, it is more likely to flow into the through-hole 6 c than to spread onto the insulating film 3, which has poor wettability.

[0016] Next, a modified example of the manufacturing method of the surface-emitting laser module according to the present embodiment will be described. Figures 8 to 10 are cross-sectional views showing modified examples of the manufacturing process of the surface-emitting laser module according to the first embodiment. First, as in the above, an electrode 4 is formed on the top surface of the surface-emitting laser chip 1, and an opening 6a and a through-hole 6c are formed in the lead frame 6.

[0017] Next, as shown in Fig. 8, the opening 6a of the lead frame 6 is positioned opposite the light emitting surface 2 of the surface-emitting laser chip 1, and the bonding portion 6b is positioned above the electrode 4 so as not to come into contact with the electrode 4. Next, as shown in Fig. 9, a bonding material 7 is applied to the bonding portion 6b of the lead frame 6. Next, as shown in Fig. 10, the bonding material 7 is melted by heating, and the electrode 4 and the bonding portion 6b are bonded by the melted bonding material 7 that has passed through the through-hole 6c. At this time, only the necessary amount of bonding material 7 on the lead frame 6 spreads toward the electrode 4 through the through-hole 6c, and does not flow out onto the light emitting surface 2.

[0018] As described above, in this embodiment, the through holes 6c are provided in the bonding portions 6b of the lead frame 6. Excess bonding material 7 flows into the narrow through holes 6c by capillary action, which prevents the bonding material 7 from flowing out onto the light emitting surface 2. As a result, the lead frame 6 can be bonded to the electrodes 4 of the surface-emitting laser chip 1 without the bonding material 7 obstructing the light emitting surface 2.

[0019] Furthermore, the lead frame 6 may be bonded to the electrodes 4 of a plurality of surface-emitting laser chips 1. In this case, the bonding material 7 can absorb variations in height of the surface-emitting laser chips 1. Furthermore, by using the lead frame 6, the wire bonding process can be eliminated, thereby shortening the takt time. Furthermore, the lead frame 6 also enables heat dissipation from the top surface side of the surface-emitting laser chip 1.

[0020] Fig. 11 is a plan view showing a first modification of the surface-emitting laser chip according to the embodiment 1. Fig. 12 is a cross-sectional view showing the first modification of the surface-emitting laser chip according to the embodiment 1. On the top surface of the surface-emitting laser chip 1, not only the electrode 4 but also the electrode 5 is provided.

[0021] 13 is a plan view showing a first modification of the surface-emitting laser module according to the first embodiment. FIG. 14 is a cross-sectional view showing the first modification of the surface-emitting laser module according to the first embodiment. The lead frame 6 is joined to the electrode 4, and the lead frame 6' is joined to the electrode 5. A through hole 6c is provided in the joint of the lead frame 6' as in the lead frame 6. This makes it possible to prevent the joint material 7 from flowing out onto the light emitting surface 2 in the lead frame 6' as well.

[0022] 15 is a cross-sectional view showing a second modification of the surface-emitting laser module according to the first embodiment. A molding resin 8 seals the surface-emitting laser chip 1 and the lead frame 6. The molding resin 8 covers the upper surface of the joint 6b. A portion of the molding resin 8 flows into the through-hole 6c from the upper surface side of the joint 6b. This prevents the molding resin 8 from peeling off.

[0023] Wiring 10 of an insulating substrate 9 is bonded to the electrode 5 on the bottom surface of the surface-emitting laser module. A submount or a heat sink may be bonded instead of the insulating substrate 9. The bottom surface of the electrode 5 is flush with the bottom surface of the mold resin 8, but the electrode 5 may protrude from the bottom surface of the mold resin 8.

[0024] Embodiment 2. Figure 16 is a plan view showing a surface-emitting laser module according to embodiment 2. The opening 6a is rectangular in plan view. The through-holes 6c extend linearly along the outer periphery of each side of the opening 6a in plan view. The small circular through-holes 6c of embodiment 1 allow the bonding material 7 to easily flow in due to capillary action, but the amount of bonding material 7 that can be stored is small. In contrast, the linear through-holes 6c of this embodiment can store a large amount of bonding material 7. This makes it easier to adjust the amount of bonding material 7 to be applied. The other configurations and effects are the same as those of embodiment 1.

[0025] Third Embodiment. Figure 17 is a cross-sectional view showing a surface-emitting laser module according to a third embodiment. The through-hole 6c has a forward tapered shape that widens from the lower surface side of the lead frame 6 toward the upper surface side. Therefore, the through-hole 6c narrows below the bonding material 7. Here, the rise in the liquid level due to capillary action is inversely proportional to the radius of the tube. Therefore, compared to the first embodiment, the bonding material 7 creeps up into the through-hole 6c more significantly. The other configurations and effects are the same as those of the first embodiment.

[0026] Fourth Embodiment Fig. 18 is a cross-sectional view showing a surface-emitting laser module according to a fourth embodiment. The through-hole 6c has an inverse tapered shape that narrows from the lower surface side of the lead frame 6 toward the upper surface side. Therefore, the through-hole 6c widens below the bonding material 7, making it easier for the bonding material 7 to enter the through-hole 6c. However, if the through-hole 6c is widened too much, the bonding material 7 will not easily creep up into the through-hole 6c. The other configurations and effects are the same as those of the first embodiment.

[0027] Fifth Embodiment Fig. 19 is a cross-sectional view showing a surface-emitting laser module according to a fifth embodiment. A protrusion 11 is provided on the lower surface of the lead frame 6 between the opening 6a and the bonding portion 6b. The protrusion 11 blocks the bonding material 7, preventing the bonding material 7 from flowing out onto the light-emitting surface 2. The protrusion 11 is in the shape of a square frame that completely surrounds the opening 6a, but can be modified according to the shape of the light-emitting surface 2 or the lead frame 6, as long as it prevents the bonding material 7 from flowing out onto the light-emitting surface 2. The other configurations and effects are the same as those of the first embodiment.

[0028] Sixth Embodiment Fig. 20 is a plan view showing a surface-emitting laser module according to a sixth embodiment. Fig. 21 is a cross-sectional view showing a surface-emitting laser module according to the sixth embodiment. A comb-tooth structure 12 is provided on the side wall of an opening 6a of a lead frame 6. The comb-tooth structure 12 is made of the same material as the lead frame 6. The comb-tooth structure 12 attracts the bonding material 7 by capillary action, so that a portion of the bonding material 7 is accommodated in the comb-tooth structure 12 to form a fillet 13. This makes it possible to prevent the bonding material 7 from flowing out onto the light emitting surface 2. The other configurations and effects are the same as those of the first embodiment.

[0029] Seventh Embodiment Fig. 22 is a plan view showing a surface-emitting laser chip according to a seventh embodiment. Fig. 23 is a cross-sectional view showing a surface-emitting laser chip according to the seventh embodiment. Fig. 24 is a cross-sectional view showing a surface-emitting laser module according to the seventh embodiment.

[0030] A groove or step is provided on the outer periphery of the top surface of the surface-emitting laser chip 1. A part of the electrode 4 is embedded in the groove or step. As a result, a recess 14 is provided on the top surface of the electrode 4 on the outer periphery side of the surface-emitting laser chip 1. The bonding material 7 flows into the recess 14 of the electrode 4 on the outer periphery side of the chip, thereby preventing the bonding material 7 from flowing out onto the light-emitting surface 2 on the central side of the chip. The other configurations and effects are the same as those of the first embodiment.

[0031] REFERENCE SIGNS LIST 1 surface-emitting laser chip, 2 light-emitting surface, 4 electrode, 6 lead frame, 6a opening, 6b bonding portion, 6c through-hole, 7 bonding material, 8 molding resin, 11 protrusion, 12 comb-tooth structure, 13 fillet, 14 recess

Claims

1. A surface-emitting laser module comprising: a surface-emitting laser chip, part of whose upper surface is a light-emitting surface; an electrode provided on the upper surface of the surface-emitting laser chip so as to surround the light-emitting surface; a lead frame having an opening provided in a position opposite the light-emitting surface and a joint provided around the opening; and a bonding material for bonding the electrode to the joint, wherein a through-hole passing vertically through the lead frame is provided in the joint.

2. The surface-emitting laser module according to claim 1, wherein a portion of the bonding material flows into the through-hole.

3. The surface-emitting laser module according to claim 1 or 2, wherein a plurality of the through holes are provided in the lead frame so as to surround the opening.

4. The surface-emitting laser module according to claim 1 or 2, wherein the through-hole extends linearly along the outer periphery of the opening in a plan view.

5. A surface-emitting laser module according to any one of claims 1 to 4, characterized in that the through-hole has a forward tapered shape that widens from the lower surface side to the upper surface side of the lead frame.

6. A surface-emitting laser module according to any one of claims 1 to 4, characterized in that the through-hole has an inverse tapered shape in which the width narrows from the lower surface side to the upper surface side of the lead frame.

7. A surface-emitting laser module according to any one of claims 1 to 6, further comprising a molding resin that seals the surface-emitting laser chip and the lead frame, the molding resin covering the upper surface of the joint, and a portion of the molding resin flowing into the through-hole from the upper surface side of the joint.

8. A surface-emitting laser module comprising: a surface-emitting laser chip, part of whose upper surface is a light-emitting surface; an electrode provided on the upper surface of the surface-emitting laser chip so as to surround the light-emitting surface; a lead frame having an opening provided in a position opposite the light-emitting surface and a joint provided around the opening; and a bonding material for bonding the electrode to the joint, wherein a protrusion is provided on the lower surface of the lead frame between the opening and the joint.

9. The surface-emitting laser module according to claim 8, wherein the protrusion blocks the bonding material to prevent it from flowing out onto the light-emitting surface.

10. A surface-emitting laser module comprising: a surface-emitting laser chip, part of whose upper surface is a light-emitting surface; electrodes provided on the upper surface of the surface-emitting laser chip so as to surround the light-emitting surface; a lead frame having an opening provided at a position opposite the light-emitting surface and a bonding portion provided around the opening; and a bonding material for bonding the electrode and the bonding portion, wherein a comb-tooth structure is provided on a side wall of the opening.

11. The surface-emitting laser module according to claim 10, wherein a portion of the bonding material is accommodated in the comb-tooth structure to form a fillet.

12. A surface-emitting laser module comprising: a surface-emitting laser chip, part of whose upper surface is a light-emitting surface; an electrode provided on the upper surface of the surface-emitting laser chip so as to surround the light-emitting surface; a lead frame having an opening provided in a position opposite the light-emitting surface and a bonding portion provided around the opening; and a bonding material for bonding the electrode to the bonding portion, wherein a recess is provided on the upper surface of the electrode on the outer periphery of the surface-emitting laser chip.

13. A method for manufacturing a surface-emitting laser module, comprising the steps of: forming an electrode on an upper surface of the surface-emitting laser chip so as to surround the light-emitting surface of the surface-emitting laser chip; forming an opening in a lead frame and forming through holes that pass through the lead frame vertically at the joint portion around the opening; applying a bonding material to the electrode; positioning the opening in the lead frame in a position facing the light-emitting surface and placing the joint portion of the lead frame on the bonding material; and melting the bonding material by heating and bonding the electrode and the joint portion with the melted bonding material.

14. A method for manufacturing a surface-emitting laser module, comprising the steps of: forming an electrode on the top surface of the surface-emitting laser chip so as to surround the light-emitting surface of the surface-emitting laser chip; forming an opening in a lead frame and forming through holes that pass vertically through the lead frame at the joint around the opening; arranging the opening in the lead frame at a position facing the light-emitting surface, arranging the joint above the electrode so as not to contact the electrode, and applying a bonding material to the joint; and melting the bonding material by heating, and bonding the electrode and the joint with the bonding material that has melted and passed through the through hole.

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