JP2004014795A - Submount for nitride semiconductor laser, and nitride semiconductor laser using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a submount for a nitride semiconductor laser which can prevent short circuit between electrodes by reducing the rate of defective goods. <P>SOLUTION: The width of a welding layer 22 corresponding to a p-side electrode 61 is made narrower than the width of the p-side electrode 61. A squeeze-out preventing layer 23 under the welding layer 22 is provided with an exposed region 23A which is not coated with the welding layer 22 along two opposite sides 22D, 22E of the welding layer 22 and a side 22F cross them. The squeeze-out preventing layer 23 is formed of a metal which is not wettable to the welding layer 22, and can prevent the welding layer 22 from squeezing out in the sides 22D, 22E, 22F by means of the exposed region 23A. It is desirable that the side 22F corresponds to the front side of the laser chip 60. In the side 22G, the welding layer 22 coats the squeeze-out preventing layer 23 and a relief region 22H extended over the squeeze-out preventing layer 23 is provided. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a nitride semiconductor laser submount and a nitride semiconductor laser using the same.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in the field of semiconductor lasers, nitride semiconductor lasers made of nitride semiconductors that can emit light in the ultraviolet to blue region have been actively developed. Since the nitride semiconductor laser emits light with higher energy than red, infrared and other semiconductor lasers, the power consumption increases, and therefore the heat generation increases.
[0003]
A heat sink made of a metal such as copper (Cu) or iron (Fe) is radiated on the back side of the substrate of the laser chip so that the heat generated by such a nitride semiconductor laser is effectively radiated to the outside. It is provided as a member. Further, between the laser chip and the heat sink, aluminum nitride having good thermal conductivity is used as a material having a relatively close thermal expansion coefficient to the substrate material of the laser chip so that stress or distortion due to a difference in thermal expansion coefficient does not occur. A submount using AlN) or the like is provided.
[0004]
FIG. 12 schematically shows a conventional method for providing a heat sink and a laser chip on both surfaces of a submount, respectively. The laser chip 110 is, for example, a nitride semiconductor laser chip in which a nitride semiconductor layer including an active layer is formed on a substrate made of sapphire, and a p-side electrode 111 and an active layer are formed on the side where the active layer is formed. An n-side electrode 112 is formed on each of the sides that are not provided. Further, a stripe structure is formed on the laser chip 110, and the current supplied from the p-side electrode 111 is partially injected into a part of the active layer near the n-side electrode 112, and is confined in that part. The amplified laser light is emitted from the light emitting point 113.
[0005]
Wiring layers 121A and 121B for wire bonding are formed on the upper surface of the submount 120. The wiring layers 121A and 121B correspond to the n-side electrode 112 and the p-side electrode 111 of the laser chip 110. Thus, a welding layer 122 is formed. On the lower surface of the submount 120, a welding layer 140 for providing the heat sink 130 is formed.
[0006]
In order to provide the laser chip 110 and the heat sink 130 on both surfaces of such a submount 120, respectively, the submount 120 and the laser chip 110 are positioned on the heat sink 130 with high precision in order, and finally, heated. Welding was performed while ensuring the positional accuracy of each using an apparatus.
[0007]
[Problems to be solved by the invention]
However, in the conventional submount 120, the welding layer 122 is formed directly on the wiring layers 121A and 121B. In addition, the width W of the welding layer 122 ₁₂₂ Is the width W of the n-side electrode 112 ₁₁₂ And the width W of the p-side electrode 111 ₁₁₁ Was the same as For this reason, conventionally, when heating and welding while applying a load to the laser chip 110, the following problem cannot be prevented with a certain probability.
[0008]
For example, as shown in FIG. 13, the welded layer 122 protrudes toward the front side of the laser chip 110 and hardens into a ball shape. As a result, the laser beam emitted from the light emitting point 113 hit the welded layer 122 solidified in a ball shape and could not travel straight, and the measurement resulted in non-light emission and a defective product.
[0009]
For example, as shown in FIG. 14, when the p-side electrode 111 and the n-side electrode 112 are formed on one surface of the laser chip 110, the protruding welding layer 122 is formed between the p-side electrode 111 and the n-side electrode. There is a risk of short-circuiting with 112.
[0010]
The present invention has been made in view of such a problem, and an object of the present invention is to use a nitride semiconductor laser submount and a nitride semiconductor laser submount capable of reducing a defective product rate and preventing a short circuit between electrodes. An object of the present invention is to provide a nitride semiconductor laser.
[0011]
[Means for Solving the Problems]
A submount for a nitride semiconductor laser according to the present invention is used for a nitride semiconductor laser having a nitride semiconductor layer including an active layer and a pair of electrodes. The submount includes a base and one side of the base. A welding layer formed with a width narrower than one of a pair of electrodes of the target semiconductor laser, and a metal which is in contact with the base-side surface of the welding layer and does not adapt to the welding layer, and A protrusion prevention layer having an exposed region which is not covered with a welding layer along two opposing sides and one side intersecting the two sides.
[0012]
A nitride semiconductor laser according to the present invention includes a laser chip having a nitride semiconductor layer including an active layer and a pair of electrodes, and a submount on which the laser chip is provided. And a welding layer fixing at least one of a pair of electrodes of the laser chip on one side of the substrate, and a metal that is in contact with the surface of the welding layer on the substrate side and does not adapt to the welding layer. And a protrusion prevention layer having an exposed region which is not covered with the welding layer along two opposing sides of the welding layer and one side intersecting the two sides.
[0013]
In the nitride semiconductor laser submount according to the present invention, the welding layer is formed to have a width smaller than one of the pair of electrodes of the nitride semiconductor laser, and is in contact with the surface of the welding layer on the substrate side. A protruding prevention layer made of a metal that does not fit into the welding layer is provided. The protruding preventing layer is provided with an exposed portion that is not covered with the welding layer along two opposing sides of the welding layer and one side intersecting the two sides. Since the region is provided, the deposited layer is prevented from protruding between the electrodes of the nitride semiconductor laser. Therefore, the defective product rate is reduced, and a short circuit is prevented. Here, one of the pair of electrodes is preferably the electrode on the side where the active layer is formed.
[0014]
In the nitride semiconductor laser according to the present invention, the welding layer of the submount fixes at least one electrode of the pair of electrodes of the laser chip, and is in contact with the surface of the welding layer on the base side, and A protrusion prevention layer made of a metal that does not fit is provided, and the protrusion prevention layer is provided with an exposed region that is not covered with the welding layer along two opposing sides of the welding layer and one side intersecting the two sides. Therefore, the welding layer is prevented from protruding between the electrodes of the laser chip. Therefore, the defective product rate is reduced, and a short circuit is prevented.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
1 and 3 show a cross-sectional configuration of a nitride semiconductor laser 10 according to one embodiment of the present invention. FIG. 2 shows an overall configuration of a nitride semiconductor light emitting device 70 including the nitride semiconductor laser 10 as a component.
[0017]
The nitride semiconductor light emitting device 70 has, for example, a disk-shaped support 71 and a hollow cylindrical lid 72. The support 71 is formed integrally with the heat sink 30 by a metal such as copper or iron. One end of the lid 72 is open, and the other end is closed. At the closed end of the lid 72, an extraction window 72A for extracting a laser beam emitted from the nitride semiconductor laser 10 housed inside to the outside of the nitride semiconductor light emitting device 70 is provided. The lid 72 is made of, for example, a metal such as copper or iron, and the extraction window 72A is made of a material capable of transmitting a laser beam emitted from the nitride semiconductor laser 10, for example, glass or plastic. ing.
[0018]
The support 71 is provided with a pair of pins 73 and 74 in a direction perpendicular to the plane of the support 71. Each of the pins 73 and 74 is made of a metal such as copper or iron, and a thin film made of gold (Au) or the like is adhered to the surface. Insulating rings 73A and 74A made of glass or the like are provided between the support 71 and the pins 73 and 74, respectively, and the support 71 and the pins 73 and 74 are electrically insulated from each other. . One end of a wire 76A made of, for example, gold having a thickness of 20 μm is joined to the pin 74. The other end of the wire 76A is joined to the wiring layer 21A, and the pin 74 is electrically connected to the wiring layer 21A. The support 71 is further provided with pins 75 electrically connected to the support 71 and the heat sink 30.
[0019]
The heat sink 30 is made of, for example, a metal such as copper or iron. The heat sink 30 is electrically connected to a power supply (not shown) of the nitride semiconductor laser 10 and has a role of dissipating heat generated by the nitride semiconductor laser 10.
[0020]
On the heat sink 30, a submount 20 having a base 20A made of aluminum nitride having a thickness of, for example, about 200 μm is provided with the welding layer 40 and the auxiliary adhesive layer 50 interposed therebetween.
[0021]
The auxiliary adhesive layer 50 includes, for example, a titanium (Ti) layer 51 having a thickness of 0.05 μm, a platinum (Pt) layer 52 having a thickness of 0.3 μm, and a gold layer 53 having a thickness of 0.6 μm laminated in this order from the submount 20 side. It was done. The welding layer 40 provided on the heat sink 30 side is made of, for example, a tin (Sn) paste having a thickness of 5.0 μm.
[0022]
On the side of the base 20A of the submount 20 where the heat sink 30 is not provided, a laser chip 60 is provided with the wiring layers 21A and 21B, the protrusion prevention layer 23 and the welding layer 22 therebetween. The laser chip 60 is made of, for example, sapphire (α-Al ₂ O ₃ ) Is provided. A nitride semiconductor layer 60B including an active layer is formed on the c-plane of substrate 60A.
[0023]
Here, the nitride semiconductor is a gallium nitride-based compound containing gallium (Ga) and nitrogen (N). For example, gallium nitride (GaN), aluminum nitride-gallium nitride (AlGaN) mixed crystal, Alternatively, a mixed crystal of aluminum nitride, gallium, and indium (AlGaInN) is used. These may be, if necessary, n-type impurities comprising Group IV and VI elements such as silicon (Si), germanium (Ge), oxygen (O), selenium (Se), or magnesium (Mg), zinc (Zn). ), Carbon (C) and other p-type impurities comprising Group II and Group IV elements.
[0024]
On the nitride semiconductor layer 60B, a p-side electrode 61 is formed on the side where the active layer is formed, and an n-side electrode 62 is formed on the side where the active layer is not formed. A stripe structure (not shown) is formed in the nitride semiconductor layer 60B of the laser chip 60, and the current supplied from the p-side electrode 61 is partially injected into a part of the active layer near the n-side electrode 62. This portion is a light emitting point 63. The p-side electrode 61 has a configuration in which, for example, palladium (Pd), platinum, and gold are sequentially stacked from the substrate 60A side.
[0025]
As shown in FIG. 3, a pair of cleavage mirror surfaces 64 and 65 are formed on both end surfaces of the laser chip 60. A translucent reflecting mirror (not shown) is provided on the cleavage mirror surface 64, and a complete reflection mirror (not shown) is provided on the cleavage mirror surface 65. These cleavage mirror surfaces 64 and 65 form a resonator structure having a resonator length L, and emit light. The light output from the point 63 is extracted through the translucent reflecting mirror of the cleavage mirror surface 64.
[0026]
The laser chip 60 having such a configuration is mounted on the base 20A of the submount 20 such that the side on which the p-side electrode 61 and the n-side electrode 62 are formed faces the base 20A of the submount 20. .
[0027]
The wiring layer 21A is, for example, a titanium layer 21A1 having a thickness of 0.05 μm and an aluminum (Al) layer 21A2 having a thickness of 1.0 μm laminated in this order from the base 20A side. It is located below. The wiring layer 21B includes a titanium layer 21B1 having a thickness of 0.05 μm and an aluminum layer 21B2 having a thickness of 1.0 μm, which are sequentially stacked from the base 20A side, and is located below the p-side electrode 61. The wiring layers 21A and 21B are formed so as to be longer than the resonator length L, and the difference d ₂₁ Is, for example, about 100 μm. Note that one end of a wire 76B made of gold having a thickness of, for example, 20 μm is joined to the wiring layer 21B. The other end of the wire 76B is joined to the heat sink 30, whereby the wiring layer 21B is connected to a power source (not shown) via the heat sink 30.
[0028]
As the welding layer 22, for example, a high melting point solder formed by laminating a plurality of metal layers including a tin layer is used. The thickness of the welded layer 22 between the p-side electrode 61 and the protrusion prevention layer 23 is extremely thin, and as shown in FIG. 3, the excess welded layer 22 protrudes to the cleavage mirror surface 65 side. However, no problem arises because the insulating property of the cleavage mirror surface 65 is ensured by a not-shown complete reflection mirror. On the other hand, the welding layer 22 between the n-side electrode 62 and the protrusion prevention layer 23 fixes the n-side electrode 62 to the protrusion prevention layer 23, and forms the laser chip 60 on the p-side electrode 61 side and the n-side electrode 62 side. Is adjusted.
[0029]
The protrusion prevention layer 23 is formed of a metal that is in contact with the lower surface of the welding layer 22 and does not adapt to the welding layer 22. When the laser chip 60 is mounted on the submount 20 by heating while applying a load, the welding layer 22 This prevents the laser chip 60 from protruding from the front side or between the p-side electrode 61 and the n-side electrode. As a material of the protrusion prevention layer 23, for example, aluminum, nickel (Ni), platinum, or the like is preferable. In the present embodiment, the protrusion prevention layer 23 is made of, for example, an aluminum layer having a thickness of 2.0 μm.
[0030]
4 to 6 show the submount 20 before the laser chip 60 is provided. The submount 20 has, for example, a wiring pattern 21A, 21B, a protrusion prevention layer 23, and a welding layer 22 formed in a predetermined pattern on one surface of a base 20A in order from the base 20A side by, for example, a vacuum deposition method. .
[0031]
The welding layer 22 has, for example, a titanium layer 22A, a silver layer 22B, and a tin layer 22C laminated in this order from the submount 20 side. In this embodiment, since the step between the p-side electrode 61 side and the n-side electrode 62 side of the laser chip 60 is adjusted by the thickness of the welding layer 22, for example, the welding on the p-side electrode 61 side is performed. In the layer 22, the thickness of the titanium layer 22A is 0.05 μm, the thickness of the silver layer 22B is 1.5 μm, and the thickness of the tin layer 22C is 4.0 μm. In the welding layer 22 on the n-side electrode 62 side, the thickness of the titanium layer 22A is 0.05 μm, the thickness of the silver layer 22B is 1.5 μm, and the thickness of the tin layer 22C is 6.0 μm. The step between the p-side electrode 61 side and the n-side electrode 62 side of the laser chip 60 may be adjusted by adjusting the thickness of the protrusion prevention layer 23.
[0032]
The width Ws of the welding layer 22 corresponding to the p-side electrode 61 is smaller than the width of the p-side electrode 61. An exposed region 23A that is not covered with the welding layer 22 is provided along the two opposing sides 22D and 22E of the welding layer 22 and a side 22F intersecting the two sides 22D and 22E of the welding layer 22 below the welding layer 22. Since the protrusion prevention layer 23 is formed of a metal that does not fit into the welding layer 22 as described above, the protrusion of the welding layer 22 on the sides 22D, 22E, and 22F can be prevented by the exposed region 23A. Therefore, there is no possibility that the welding layer 22 protruding between the p-side electrode 61 and the n-side electrode 62 causes a short circuit. In addition, it is possible to prevent a short circuit caused by the welding layer 22 protruding from the side 22D coming into contact with the PN junction exposed on the side surface of the nitride semiconductor layer 60B.
[0033]
Further, since the exposed region 23A is not covered with the welding layer 22 and is in a state of being in direct contact with the p-side electrode 61, heat generated by the laser is dissipated through the protruding prevention layer 23, and the stability of the high-temperature operation is improved. Characteristics can also be improved. At this time, in addition to the metal that does not fit into the welding layer 22 as described above, the material of the protrusion prevention layer 23 has a thermal conductivity equal to or higher than that of the welding layer 22, for example, aluminum, platinum, or the like. It is preferable to use nickel or the like because such an effect can be further enhanced.
[0034]
A side 22F of the welding layer 22 that intersects the two opposite sides 22D and 22E corresponds to a front side of the laser chip 60, that is, a cleavage mirror surface 64 which is an end face on the side from which light output of the laser chip 60 is taken out. Is preferred. This is because it is possible to prevent the molten welding layer 22 from protruding from the side 22F to the front side of the laser chip 60 and hindering the laser light output.
[0035]
Further, on the other side 22G that intersects the two opposite sides 22D and 22E of the welding layer 22, the welding layer 22 covers the protrusion prevention layer 23 and has a relief area 22H extending beyond the protrusion prevention layer 23. Is preferred. Thereby, a region can be formed in which the unnecessary welding layer 22 discharged from between the p-side electrode 61 and the protrusion prevention layer 23 escapes.
[0036]
The width W of such an exposed region 23A _23A Is preferably, for example, 2 μm or more and 10 μm or less. If it is smaller than 2 μm, the effect of preventing protrusion cannot be sufficiently obtained, and if it is larger than 10 μm, the amount of the welding layer 22 becomes small and the necessary welding force cannot be obtained.
[0037]
Further, the thickness of the protrusion prevention layer 23 can be appropriately set according to the thickness of the welding layer 22, but the total thickness of the welding layer 22 (the total thickness of the titanium layer 22A, the silver layer 22B, and the tin layer 22C). Is preferably smaller than the total thickness of the welded layer 22 by, for example, about 2 μm. In this case, when the total thickness of the welding layer 22 is different between the p-side electrode 61 side and the n-side electrode 62 side, the total thickness of the thinner welding layer 22 is used as a reference.
[0038]
The width Wt of the welding layer 22 corresponding to the n-side electrode 62 is, for example, smaller than the width Wn of the n-side electrode 62. The exposed area 23A is provided on the three sides 22D, 22E, and 22F of the protrusion prevention layer 23 below the welding layer 22 corresponding to the n-side electrode 62, similarly to the welding layer 22 on the p-side electrode 61 side. However, for example, an exposed region 23A is provided along the two sides 22D and 22F of the welding layer 22, and a protrusion prevention frame 23B made of the same material as the protrusion prevention layer 23 is formed on the side 22E. It is preferable that a gap 23C is provided between the protrusion prevention layer 23 and the protrusion prevention frame 23B. If the thickness of the weld layer 22 corresponding to the n-side electrode 62 is large as in the present embodiment, it is difficult to discharge the weld layer 22 only to the side 22G. However, in this case as well, on the side 22F corresponding to the cleavage mirror surface 64 on the front side, that is, the side from which light output is taken out, the protrusion prevention layer 23 is not cut off by the gap 23C and is continuously integrated as shown in FIG. Is preferably provided. This is because the welding layer 22 can be prevented from protruding from the gap 23C to the front side. In addition, a relief area 22H for discharging and escaping the excess welding layer 22 is provided on the side 22G.
[0039]
In addition, the width W of the protrusion prevention frame 23B _23B And the width W of the gap 23C _23C Is, for example, the width W of the exposed region 23A. _23A Can be the same as
[0040]
The nitride semiconductor laser 10 having such a configuration can be manufactured as follows.
[0041]
First, as shown in FIG. 7, a base 20A made of aluminum nitride having a thickness of, for example, about 200 μm is prepared. On one surface of the substrate 20A, that is, the surface on which the heat sink 30 is provided, for example, a titanium layer 51 having a thickness of 0.05 μm, a platinum layer 52 having a thickness of 0.3 μm, and a gold layer having a thickness of 0.6 μm are formed by vacuum evaporation. 53 are sequentially deposited to form the auxiliary adhesive layer 50.
[0042]
Subsequently, on the other surface of the base 20A, that is, the surface on which the laser chip 60 is provided, the titanium layers 21A1 and 21B1 having a thickness of 0.05 μm are formed by, for example, a vacuum evaporation method. Next, aluminum layers 21A2 and 21B2 having a thickness of 1.0 μm are deposited on the titanium layers 21A1 and 21B1. As described above, the wiring layers 21A and 21B including the titanium layers 21A1 and 21B1 and the aluminum layers 21A2 and 21B2 are formed.
[0043]
Next, on the wiring layers 21A and 21B, a protrusion prevention layer 23 made of an aluminum layer having a thickness of 2.0 μm is formed by, for example, a vacuum evaporation method. Further, the welding layer 22 is formed on the protrusion prevention layer 23. At this time, the widths Ws and Wt of the welded layer 22 are made smaller than the widths Wp and Wn of the p-side electrode 61 and the n-side electrode 62, respectively, and a relief area 22H is formed on the side 22G of the welded layer 22. In addition, the exposed region 23A, the exposed frame 23B, and the gap 23C are provided in the protrusion prevention layer 23. Thus, the submount 20 having the wiring layers 21A and 21B, the protrusion prevention layer 23, and the welding layer 22 formed on one surface of the base 20A, and the auxiliary adhesive layer 50 formed on the other surface is formed.
[0044]
Next, as shown in FIG. 8, the heat sink 30 integrally molded with the support 71 on which the pins 73, 74, 75 are provided is prepared. An adhesive layer 40 made of tin paste is formed on the heat sink 30 by using, for example, stamping or a needle.
[0045]
Subsequently, as shown in FIG. 9, the submount 20 is placed on the heat sink 30 on which the adhesive layer 40 is formed with the surface on which the auxiliary adhesive layer 50 is formed facing the submount 20, and positioning is performed accurately. .
[0046]
Next, as shown in FIG. 10, a laser chip 60 in which a nitride semiconductor layer 60B including an active layer and a pair of a p-side electrode 61 and an n-side electrode 62 are formed on one surface side of a substrate 60A. prepare. The side of the laser chip 60 having the p-side electrode 61 and the n-side electrode 62 corresponds to the side of the base 20A of the submount 20 on which the welding layer 22 is formed. A laser chip 60 on the substrate. At this time, the thickness of the welded layer 22 adjusts the step between the p-side electrode 61 side and the n-side electrode 62 side of the laser chip 60, so that the wiring layer 21 </ b> A is located below the n-side electrode 62. When the wiring layer 21B is located below the p-side electrode 61, the laser chip 60 can be placed horizontally on the submount 20.
[0047]
Next, a load is applied from the substrate 60A side of the laser chip 60 by a collet device (not shown), and the laser chip 60, the submount 20, and the heat sink 30 are adhered by performing a heating process from the heat sink 30 side with, for example, a heating device.
[0048]
Subsequently, the wire 76A is joined between the wiring layer 21A and the pin 74, and the wire 76B is joined between the wiring layer 21B and the heat sink 30. Thus, the nitride semiconductor laser 10 shown in FIG. 1 is completed. Next, for example, in a dry nitrogen atmosphere, a separately formed lid 72 is disposed on the support 71 of the nitride semiconductor laser 10. Thus, the nitride semiconductor light emitting device 70 shown in FIG. 2 is completed.
[0049]
As described above, in the present embodiment, the width Ws of the welding layer 22 corresponding to the p-side electrode 61 is smaller than the width of the p-side electrode 61, and the protrusion prevention layer 23 below the welding layer 22 has An exposed region 23A that is not covered by the welding layer 22 is provided along two opposing sides 22D and 22E of the welding layer 22 and a side 22F that intersects the two sides 22D and 22E. Even if the layer 22 attempts to protrude, the exposed region 23A can effectively prevent the welding layer 22 from protruding on the sides 22D, 22E, and 22F. Therefore, there is no possibility that the welding layer 22 causes a short circuit between the p-side electrode 61 and the n-side electrode 62. In addition, it is possible to prevent short-circuiting caused by the fact that the welded layer 22 protruding from the side 22D contacts the PN junction exposed on the side surface of the nitride semiconductor layer 60B.
[0050]
Further, since the exposed region 23A is not covered with the welding layer 22 and is in a state of being in direct contact with the p-side electrode 61, heat generated by the laser is dissipated through the protruding prevention layer 23, and the stability of the high-temperature operation is improved. Characteristics can be improved.
[0051]
In addition, as the material of the protrusion prevention layer 23, in addition to a metal that does not fit into the welding layer 22 as described above, if a material having a thermal conductivity equal to or higher than that of the welding layer 22 is used, the heat generation of the laser Can be further enhanced.
[0052]
A side 22F of the welding layer 22 that intersects the two opposite sides 22D and 22E corresponds to a front side of the laser chip 60, that is, a cleavage mirror surface 64 which is an end face on the side from which light output of the laser chip 60 is taken out. Therefore, it is possible to prevent the molten welding layer 22 from protruding from the side 22F to the front side of the laser chip 60 and hindering the laser beam output.
[0053]
Further, on the other side 22G that intersects the two opposite sides 22D and 22E of the welding layer 22, the welding layer 22 covers the protrusion prevention layer 23 and has a relief area 22H extending beyond the protrusion prevention layer 23. Therefore, a region can be formed in which the unnecessary welding layer 22 discharged from between the p-side electrode 61 and the protrusion prevention layer 23 escapes.
[0054]
Also, the width Wt of the welding layer 22 corresponding to the n-side electrode 62 is smaller than the width Wn of the n-side electrode 62, and the protrusion prevention layer 23 thereunder has two sides 22D of the welding layer 22. , 22F, an exposed region 23A is provided, and on the side 22E, an extruded frame 23B made of the same material as the extruded layer 23 is formed. Between the extruded layer 23 and the extruded frame 23B, Since the gap 23C is provided, even if the thickness of the welding layer 22 corresponding to the n-side electrode 62 is large, it is possible to prevent the welding layer 22 from protruding.
[0055]
As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the above embodiment, and can be variously modified. For example, in the above embodiment, aluminum nitride is used as the base 20A of the submount 20, but silicon (Si) or diamond (C) may be used. In the above embodiment, the wiring layers 21A and 21B are composed of the titanium layers 21A1 and 21B1 and the aluminum layers 21A2 and 21B2 in this order from the base 20A side. However, a gold layer may be used instead of the aluminum layers 21A2 and 21B2. . Further, the auxiliary adhesive layer 50 is composed of the titanium layer 51, the platinum layer 52 and the gold layer 53 in this order from the side of the base 20A of the submount 20, but the aluminum layer may be used instead of the gold layer 53. Further, in the above embodiment, the configuration, material, or thickness of each layer is shown together with a specific example. However, another layer may be provided, and the material may be another material. Also, the thickness can be changed or adjusted as appropriate.
[0056]
Further, in the present embodiment, an example in which the width Wt of the welding layer 22 corresponding to the n-side electrode 62 is formed to be smaller than the width Wn of the n-side electrode 62 has been described. In the layer 22, the width Wt of the welding layer 22 may be the same as the width Wn of the n-side electrode 62 as long as the protrusion prevention frame 23B and the gap 23C are provided.
[0057]
In the present embodiment, the step between the p-side electrode 61 side and the n-side electrode 62 side of the laser chip 60 is adjusted by adjusting the thickness of the welding layer 22. When the thickness of the prevention layer 23 is adjusted, the thickness of the welding layer 22 can be made equal between the p-side electrode 61 side and the n-side electrode 62 side. On the side 22E of the protrusion prevention layer 23, the protrusion prevention frame 23B may not be provided, and the exposed region 23A may be provided similarly to the p-side electrode 61 side.
[0058]
In addition, in the present embodiment, the case where a sapphire substrate is used as the substrate 60A of the laser chip 60 and the p-side electrode 61 and the n-side electrode 62 are provided on one side thereof has been described. As shown in FIG. 11, the present invention can be applied to a case where a gallium nitride substrate is used as the substrate 60A and the p-side electrode 61A and the n-side electrode 62A are arranged on different surfaces of the substrate 60A. In this case, only the wiring layer 21B and the overlying prevention layer 23 and the welding layer 22 may be formed on the surface of the base 20A of the submount 20 on which the laser chip 60 is provided.
[0059]
【The invention's effect】
As described above, the nitride semiconductor laser submount according to any one of claims 1 to 10, or the nitride semiconductor laser according to any one of claims 11 to 16, According to this, the welding layer is formed with a width smaller than one electrode of the nitride semiconductor laser or the laser chip, and the protruding prevention layer has two sides facing the welding layer and one side intersecting these sides. Since the exposed region that is not covered with the welding layer is provided, the exposed region can prevent the welding layer from protruding. Therefore, there is no danger of a short circuit between the electrodes due to the welding layer. Further, it is possible to prevent a short circuit caused by the protruding welding layer coming into contact with the PN junction exposed on the side surface of the nitride semiconductor laser.
[0060]
In particular, according to the nitride semiconductor laser according to the twelfth aspect, the exposed region is not covered with the welding layer and is in a state of being in direct contact with the electrode, so that the heat generated by the laser is radiated through the protrusion prevention layer. In addition, laser characteristics such as high-temperature operation stability can be improved.
[0061]
In addition, in particular, according to the nitride semiconductor laser submount according to claim 3 or the nitride semiconductor laser according to claim 15, a material having a thermal conductivity equal to or higher than that of the welding layer is used as the material of the protrusion prevention layer. Since it is used, the effect of dissipating the heat generated by the laser can be further enhanced.
[0062]
In addition, in particular, according to the nitride semiconductor laser submount according to the fourth aspect or the nitride semiconductor laser according to the sixteenth aspect, the laser beam output is extracted from one side crossing the two opposing sides of the welding layer. Therefore, it is possible to prevent the molten welding layer from protruding toward the front side of the laser and hindering the laser light output.
[0063]
In addition, in particular, in the nitride semiconductor laser submount according to claim 7, on the other side crossing the two opposing sides of the welding layer, the welding layer covers the protrusion prevention layer and extends beyond the protrusion prevention layer. Since the extended escape area is provided, an area for the unnecessary welding layer discharged from between the electrode and the protrusion prevention layer to escape can be formed.
[0064]
In particular, in the nitride semiconductor laser submount according to any one of claims 8 to 10, the width of the other welding layer corresponding to the other electrode of the nitride semiconductor laser is larger than that of the other electrode. Is formed with a narrow width or the same width, and the protrusion prevention layer is provided with an exposed region along at least one of two opposing sides of another welding layer and one side intersecting the two opposing sides. Therefore, it is possible to prevent the welding layer from protruding by the exposed region. Therefore, there is no danger of a short circuit between the electrodes due to the welding layer.
[0065]
In particular, in the nitride semiconductor laser submount according to the ninth or tenth aspect, the protrusion prevention frame is formed along the side where the exposed region is not provided among the two opposing sides of the other welding layer, Since the gap is provided between the protrusion prevention layer and the protrusion prevention frame, even if the thickness of the welding layer corresponding to the other electrode is large, it is possible to prevent the welding layer from protruding.
[Brief description of the drawings]
FIG.
FIG. 1 is a cross-sectional view illustrating a configuration of a nitride semiconductor laser according to one embodiment of the present invention.
FIG. 2
Nitride semiconductor light emitting device including nitride semiconductor laser shown in FIG. 1 as a constituent element
It is a perspective view showing the whole structure of.
FIG. 3
FIG. 3 is a cross-sectional view of the nitride semiconductor laser shown in FIG. 1 along the line III-III.
FIG. 4
The state of the submount shown in FIG.
It is the top view seen from the surface by the side in which a chip is provided.
FIG. 5
FIG. 5 is a sectional view taken along line VV of FIG. 4.
FIG. 6
FIG. 6 is a cross-sectional view along the line VI-VI in FIG. 4.
FIG. 7
FIG. 2 is a cross-sectional view illustrating a method of manufacturing the nitride semiconductor laser illustrated in FIG. 1 in a process order.
FIG. 8
FIG. 8 is a cross-sectional view illustrating a process following the process in FIG. 7.
FIG. 9
FIG. 9 is a cross-sectional view illustrating a process following the process in FIG. 8.
FIG. 10
FIG. 10 is a cross-sectional view illustrating a process following the process in FIG. 9.
FIG. 11
FIG. 4 is a cross-sectional view illustrating a modification of the nitride semiconductor laser illustrated in FIG. 1.
FIG.
FIG. 4 is a cross-sectional view for describing a conventional method for manufacturing a nitride semiconductor laser.
13 is a cross-sectional view for explaining an example of a problem of the manufacturing method shown in FIG.
14 is a cross-sectional view for explaining another example of the problem of the manufacturing method shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Nitride semiconductor laser, 20 ... Submount, 20A ... Base, 21A, 21B ... Wiring layer, 22 ... Welding layer, 23 ... Extrusion prevention layer, 23A ... Exposed area, 23B ... Extrusion prevention frame, 23C ... Gap, 22D , 22E, 22F, 22G ... side, 22H ... escape area, 30 ... heat sink, 40 ... welding layer, 50 ... auxiliary adhesive layer, 60 ... laser chip, 61A ... substrate, 60B ... nitride semiconductor layer, 61, 61A ... p Side electrode, 62, 62A n-side electrode, 63 light emitting point, 70 nitride semiconductor light emitting device, 71 support, 72 cover, 72A extraction window, 73, 74, 75 pin, 73A, 74A ... insulating ring, 76A, 76B ... wire

Claims (16)

A submount for a nitride semiconductor laser used for a nitride semiconductor laser having a nitride semiconductor layer including an active layer and a pair of electrodes,
A substrate;
On one side of the base, a welding layer formed with a narrower width than one of the pair of electrodes of the nitride semiconductor laser,
The welding layer is formed of a metal that is in contact with the surface of the base material side and does not adapt to the welding layer, and is covered with the welding layer along two opposing sides of the welding layer and one side intersecting the two sides. A submount for a nitride semiconductor laser, comprising: a protrusion prevention layer having an exposed region that is not exposed. 2. The nitride semiconductor laser submount according to claim 1, wherein said one electrode is an electrode on a side where said active layer is formed. The submount for a nitride semiconductor laser according to claim 1, wherein the protrusion prevention layer is formed of a material having a thermal conductivity equal to or higher than that of the welding layer. 2. The submount for a nitride semiconductor laser according to claim 1, wherein one side intersecting the two opposing sides corresponds to an end face on a side from which light output of the nitride semiconductor laser is taken out. 2. The submount for a nitride semiconductor laser according to claim 1, wherein the width of the exposed region is 2 μm or more and 10 μm or less. 2. The submount for a nitride semiconductor laser according to claim 1, wherein the thickness of the protrusion prevention layer is smaller than the thickness of the welding layer. The other side intersecting the two opposite sides, the welding layer covers the protrusion prevention layer, and a relief region extending beyond the protrusion prevention layer is provided. 2. The submount for a nitride semiconductor laser according to 1. On the same side as the welding layer of the base, another welding layer formed with a smaller width or the same width as the other electrode of the pair of electrodes of the nitride semiconductor laser,
The other welding layer is formed of a metal that is in contact with the surface on the substrate side of the other welding layer and is not compatible with the other welding layer, and at least one of the two opposite sides of the other welding layer and the two opposite sides. 2. A submount for a nitride semiconductor laser according to claim 1, further comprising another protrusion prevention layer having an exposed region which is not covered with said another welding layer along one side intersecting with the other. The other protrusion prevention layer has a protrusion prevention frame along a side where the exposed region is not provided among two opposing sides of the other welding layer, and the protrusion prevention frame and the protrusion prevention layer 9. The submount for a nitride semiconductor laser according to claim 8, wherein a gap is provided between the submounts. 10. The nitride semiconductor laser according to claim 9, wherein the other protrusion prevention layer is provided continuously and integrally on one side intersecting the two opposite sides without being disconnected by the gap. For submount. A laser chip having a nitride semiconductor layer including an active layer and a pair of electrodes, and a submount provided with the laser chip, wherein the submount is
A substrate;
On one side of the base, a welding layer fixing at least one electrode of the pair of electrodes of the laser chip,
The welding layer is formed of a metal that is in contact with the surface of the base material side and does not adapt to the welding layer, and is covered with the welding layer along two opposing sides of the welding layer and one side intersecting the two sides. A nitride semiconductor laser comprising: a protrusion prevention layer having an exposed region that is not exposed. The nitride semiconductor laser according to claim 11, wherein the exposed region is in direct contact with the one electrode. The nitride semiconductor laser according to claim 11, wherein a heat radiating member is provided on a side of the submount opposite to a side on which the laser chip is provided. The nitride semiconductor laser according to claim 11, wherein the one electrode is an electrode on a side on which the active layer is formed. The nitride semiconductor laser according to claim 11, wherein the protrusion prevention layer is formed of a material having a thermal conductivity equal to or higher than that of the welding layer. 12. The nitride semiconductor laser according to claim 11, wherein one side intersecting the two opposing sides corresponds to an end face on a side from which light output of the nitride semiconductor laser is extracted.

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