JP2003258365A - Semiconductor laser device, manufacturing method of thereof and semiconductor laser module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device which realizes a long life and stabilization while conducting high output by using a semiconductor laser element of a large cavity length, by relaxing strain caused by different in linear expansion coefficient of a semiconductor laser element and a submount. <P>SOLUTION: A metallic thin film 15 is formed by an electrolytic plating method in an inner region which is in a surface of a p-side electrode layer 16 of a semiconductor laser element 9 and is apart from an end of the layer 16 by a prescribed width. The film 15 is jointed via a solder layer 14 applied on a submount 12. The semiconductor laser element 9 is thereby fixed on the submount 12. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser device and a semiconductor laser module which realize a long life and stabilization, and more particularly to a structure of a joint portion between a semiconductor laser element and a submount located below the semiconductor laser element. The present invention relates to a characteristic semiconductor laser device, a semiconductor laser module, and a method of manufacturing a semiconductor laser device.

[0002]

2. Description of the Related Art In recent years, due to the rapid spread of the Internet and the rapid increase in intra-company LAN connections, an increase in data traffic has become a problem. To prevent deterioration of communication performance, high-density wavelength division multiplexing is used. (DWDM:
Dense-Wavelength Division Multiplexing) Transmission systems have made remarkable progress and are becoming popular.

In the DWDM transmission system, a plurality of optical signals are put on different wavelengths, respectively, so that a single fiber realizes large-capacity transmission up to 100 times that of the conventional one. Here, in the signal light source or the amplification light source used in the DWDM transmission system, the oscillation wavelength needs to be controlled with high accuracy, and it is necessary to prevent thermal saturation of the semiconductor laser device and operate with a high optical output. . Therefore, in the conventional semiconductor laser device, a thermistor for measuring the temperature of the semiconductor laser element is provided in the vicinity of the semiconductor laser element that outputs laser light, and the temperature control element such as a Peltier element controls the temperature of the semiconductor laser element. In order to prevent instability of the oscillation wavelength and thermal saturation of the semiconductor laser device (see, for example, Patent Document 1).

FIG. 16 is a perspective view showing a schematic structure of a conventional semiconductor laser device. 16, in this semiconductor laser device, a submount 102 made of AlN having an insulating property and a high thermal conductivity is provided on a carrier 101 made of CuW.
A semiconductor laser element 103 that outputs a laser beam L100 having a predetermined wavelength is provided on the laser light source 2. Also, the carrier 101
A submount 104 made of AlN is provided on the upper side, and a thermistor 105 for measuring the temperature of the semiconductor laser element is further provided on the submount 104.

Semiconductor laser device 103 and submount 1
02 is bonded via the metal thin film 102a. The metal thin film 102a has a Ti / Pt / Au content of 60, respectively.
nm / 200 nm / 600 nm of metallized film and the metallized solder material such as AuSn is used to form the semiconductor laser element 103 and the submount 10.
Two are joined. In addition, the thermistor 105 and the submount 104 are similarly bonded via the metal thin film 104a.

The semiconductor laser device 103 has a p-side electrode on the surface to be joined to the submount 102 and an n-side electrode on the other upper surface.
It has a side electrode. Further, the semiconductor laser element 103 is fixed by so-called junction down in which an active layer that mainly generates heat is arranged near the submount 102 side.
The negative electrode of the n-side electrode is led by the Au wire 106a. The p-side electrode is lead to the carrier 101 on the positive electrode side through the metal thin film 102a and the Au wire 106b.

As a result, the submount 102 ensures the insulation of the semiconductor laser device 103 and also functions as a heat sink for the semiconductor laser device 103. In addition, the submount 102 is attached to the lower part of the carrier 101
A Peltier module (not shown) joined to a CuW base (not shown) joined by uSn solder controls the temperature of the semiconductor laser element 103 according to the temperature detected by the thermistor 105.

As with the semiconductor laser device 103, the thermistor 105 is also insulated from the carrier 101 by the submount 104, and the semiconductor laser device 103 via the submount 102, the carrier 101 and the submount 104, which has high thermal conductivity. Detects the temperature of.

[0009]

[Patent Document 1] Japanese Patent Laid-Open No. 2000-340878

[0010]

By the way, the above-mentioned D
In the WDM transmission system, in order to increase the distance between the repeaters, it is required to increase the output power of the laser light of the signal light source. Further, in order to improve the amplification capability of the optical fiber amplifier, it is required to increase the output of the semiconductor laser device used as the pumping light source.

It is known that increasing the cavity length of the semiconductor laser element 103 and improving the heat dissipation are effective means for realizing a large output of laser light in the semiconductor laser device. . However, an increase in cavity length leads to an increase in heat generation, and ultimately improvement in heat dissipation is the key to achieving higher output.

Therefore, the submount 102 described above is formed of a material having a high heat dissipation property such as diamond, or the semiconductor laser element 103 is arranged with the above junction down to enhance the heat dissipation efficiency.

However, due to the difference in the linear expansion coefficient between the submount 102 such as diamond and the semiconductor laser element 103, the characteristics of the semiconductor laser element 103 are repeated while the heat generation and cooling by the submount 102 are repeated in the semiconductor laser element 103. There was a problem of deterioration and damage.

The present invention has been made in view of the above, and by devising the structure of the metal thin film 102a and the like interposed between the semiconductor laser element 103 and the submount 102, distortion caused by a difference in linear expansion coefficient is generated. It is an object of the present invention to provide a semiconductor laser device and a semiconductor laser module that are relaxed and achieve a high output by using a semiconductor laser element having a large cavity length while achieving a long life and stabilization.

[0015]

In order to achieve the above object, a semiconductor laser device according to a first aspect of the present invention comprises a first electrode layer (n-side electrode layer 1 to be described later) for injecting a current into an active layer.
Equivalent to 8. ) And a second electrode layer, and a first metal thin film layer (metal thin film 15 described later) formed on the surface of the second electrode layer (corresponding to a p-side electrode layer 16 described later). Corresponding to a submount (corresponding to a submount 12 described later) having a second metal thin film layer (corresponding to a metal thin film 13 described below) formed on the surface thereof while having insulation and high thermal conductivity. .) And a solder layer (corresponding to a solder layer 14 to be described later) for joining the first metal thin film layer and the second metal thin film layer to each other, and the second electrode layer and the first electrode layer. Each of the metal thin film layer, the solder layer, and the second metal thin film layer contains Au as a main component, and the total thickness is 5 to 25 μm.

According to a second aspect of the semiconductor laser device, a semiconductor laser element sandwiched between a first electrode layer and a second electrode layer for injecting a current into an active layer, and a surface of the second electrode layer are provided. The formed first metal thin film layer, a submount having an insulating property and high thermal conductivity, and a second metal thin film layer formed on the surface thereof, the first metal thin film layer and the second metal thin film layer. A solder layer for joining, and the first metal thin film layer is formed in an inner region having an outer edge at a position inside a predetermined width from an end of the second electrode layer.

According to a third aspect of the semiconductor laser device, a semiconductor laser element sandwiched between a first electrode layer and a second electrode layer for injecting a current into the active layer, and a surface of the second electrode layer are provided. The formed first metal thin film layer, a submount having an insulating property and high thermal conductivity, and a second metal thin film layer formed on the surface thereof, the first metal thin film layer and the second metal thin film layer. A solder layer for joining, wherein the distance between the active layer and the second electrode layer is smaller than the distance between the active layer and the first electrode layer, and the active layer is activated by thermal expansion. It is characterized by a distance that minimizes the stress experienced by the layers.

According to a fourth aspect of the semiconductor laser device, a semiconductor laser element sandwiched between a first electrode layer and a second electrode layer for injecting a current into an active layer, and a surface of the second electrode layer. The formed first metal thin film layer, a submount having an insulating property and high thermal conductivity, and a second metal thin film layer formed on the surface thereof, the first metal thin film layer and the second metal thin film layer. A solder layer for joining, wherein the second electrode layer, the first metal thin film layer, the solder layer and the second metal thin film layer each have Au as a main component, and the total thickness of each is 5 to 5. The thickness is 25 μm, and the first metal thin film layer is formed in an inner region having an outer edge at a position inside a predetermined width from the end of the second electrode layer.

According to a fifth aspect of the semiconductor laser device, a semiconductor laser element sandwiched between a first electrode layer and a second electrode layer for injecting a current into the active layer, and a surface of the second electrode layer. The formed first metal thin film layer, a submount having an insulating property and high thermal conductivity, and a second metal thin film layer formed on the surface thereof, the first metal thin film layer and the second metal thin film layer. A solder layer for joining, wherein the second electrode layer, the first metal thin film layer, the solder layer and the second metal thin film layer each have Au as a main component, and the total thickness of each is 5 to 5. 25 μm, the distance between the active layer and the second electrode layer is smaller than the distance between the active layer and the first electrode layer, and the stress applied to the semiconductor laser element by thermal expansion is minimized. It is characterized by the distance to limit .

A semiconductor laser device according to a sixth aspect of the present invention is the semiconductor laser device according to the above-mentioned invention, wherein the semiconductor laser device is sandwiched between a first electrode layer and a second electrode layer for injecting a current into the active layer, A first metal thin film layer formed on the surface of the electrode layer, a submount having insulation and high thermal conductivity, and a second metal thin film layer formed on the surface, the first metal thin film layer, and the second metal thin film layer. A solder layer for joining with a metal thin film layer, wherein the second electrode layer, the first metal thin film layer, the solder layer and the second metal thin film layer each contain Au as a main component and have respective thicknesses. Of 5 to 25 μm, the first metal thin film layer is formed in an inner region having an outer edge at a position inside a predetermined width from the end of the second electrode layer, and the active layer and the second electrode are formed. The distance between the active layer and the first electrode is Is characterized in that a distance to minimize the semiconductor laser element is subjected stress by small and thermal expansion than the distance between the.

According to a seventh aspect of the present invention, in the semiconductor laser device according to the above-mentioned invention, the second electrode layer is a multi-layer film composed of a plurality of metal films, and at least the metal film of the plurality of metal films. It is characterized in that the metal film in contact with the first metal thin film layer contains Au as a main component.

According to an eighth aspect of the present invention, in the semiconductor laser device according to the above invention, the first metal thin film layer is Au.
Is formed by an electrolytic plating method containing at least 1
It is characterized by having a thickness of μm.

According to a ninth aspect of the present invention, in the semiconductor laser device according to the above invention, the first metal thin film layer is Au.
Is formed by an electrolytic plating method containing at least 6
It is characterized by having a Vickers hardness of less than 5.

Further, a semiconductor laser device according to a tenth aspect of the present invention is characterized in that, in the above-mentioned invention, the first metal thin film layer has a planar shape having a convex portion on one of the longitudinal end portions.

According to an eleventh aspect of the present invention, in the semiconductor laser device according to the eleventh aspect of the present invention, the solder layer contains Au as a main component, and the eutectic crystal that minimizes strain applied to the semiconductor laser element due to thermal expansion. The composition is characterized by having a temperature.

According to a twelfth aspect of the present invention, in the semiconductor laser device according to the above invention, the solder layer is Au: S.
It is characterized by being formed of AuSn having a composition ratio of n = 74 to 80:26 to 20.

According to a thirteenth aspect of the present invention, in the semiconductor laser device according to the above invention, the second metal thin film layer is a multi-layer film composed of a plurality of metal films, and at least one of the plurality of metal films. One of the metal films is mainly composed of Au, and the thickness of the metal film is larger than the total thickness of the other metal films.

According to a fourteenth aspect of the present invention, in the above-mentioned invention, the semiconductor laser device is characterized in that the submount is made of diamond.

According to a fifteenth aspect of the present invention, in the semiconductor laser device according to the above invention, the cavity length is 800 μm.
It is characterized by the above.

A semiconductor laser module according to a sixteenth aspect is the semiconductor laser device according to any one of the first to fifteenth aspects, a temperature measuring element for measuring a driving temperature of the semiconductor laser element, and the temperature. A temperature control element for controlling the temperature of the semiconductor laser device based on the temperature output from the measurement element, wherein the submount is bonded above the temperature control element, and the semiconductor is mounted via the submount. The laser device is characterized in that its temperature is controlled.

A method of manufacturing a semiconductor laser device according to a seventeenth aspect of the present invention includes a step of forming a semiconductor laser element,
A step of forming a metal thin film on the surface of the semiconductor laser element and on a side where the semiconductor laser element is fixed to a support, and a step of subjecting the metal thin film to a heat treatment. I am trying.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a semiconductor laser device and a semiconductor laser module according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited to this embodiment.

(First Embodiment) First, a semiconductor laser device according to the first embodiment will be described. Embodiment 1
In the semiconductor laser device according to the present invention, the electrodes of the semiconductor laser element, the metal thin film serving as the buffer layer, the solder layer serving as the conductive adhesive, and the metal thin film on the submount serving as the wiring drawing layer are made of Au-based materials. It is characterized in that it is formed to include and is arranged so as to be positioned in the above-mentioned order.

FIG. 1 is an explanatory diagram for explaining the configuration of the semiconductor laser device according to the first embodiment. In particular, FIG. 1A shows a sectional view of the semiconductor laser device, and the direction perpendicular to the plane of the drawing coincides with the laser emission direction. Also, FIG.
(B) shows the AA sectional view of FIG. Further, FIG. 2 is a perspective view of FIG. In FIG. 1, a semiconductor laser device 10 includes a carrier 1 formed of AlN or the like.
A submount 12 made of diamond having an insulating property and a high thermal conductivity is provided on the submount 1, and a semiconductor laser element 9 for outputting a laser beam having a predetermined wavelength is provided on the submount 12.

As shown in FIG. 1A, a p-side electrode layer 16 is formed on one surface side of the semiconductor laser device 9, and an n-side electrode layer 18 is formed on the other surface side opposite thereto. Also, p
The metal thin film 15 is formed on the surface of the side electrode layer 16.
As the semiconductor laser element 9, for example, an InP-based 1.48 μm band oscillation semiconductor laser element can be used, and its cavity length is 8 to realize high output.
It is preferably at least 00 μm.

On the other hand, the metal thin film 1 is placed on the submount 12.
3 is formed. Then, a solder layer 14 is applied on the metal thin film 13, and the above-mentioned metal thin film 15 is bonded via the solder layer 14. As a result, the semiconductor laser element 9 is fixed, and the electrode wiring can be pulled out from the p-side electrode layer 16 via the metal thin film 13. In the semiconductor laser device 9, the active layer 3 is located closer to the p-side electrode layer 16 and is fixed in the above-mentioned junction-down form.

Here, the shape of the above-mentioned metal thin film 15 will be described. The metal thin film 15 is shown in FIG.
As shown in FIG. 5, the layer is not formed on the entire surface of the p-side electrode layer 16, but is formed in an inner region separated from the end of the p-side electrode layer 16 by predetermined widths d1 and d2. The vertical width d1 and the horizontal width d2 in the figure may be the same or different. When the lengths are the same, the length is, for example, 25 μm. Further, when the semiconductor laser element 9 integrated with the metal thin film 15 is fixed on the solder layer 14, the metal thin film 1 can be easily confirmed on the emitting end face side.
The tip portion in the longitudinal direction of 5 may have a convex shape 19.

As described above, by forming a region where the metal thin film 15 does not exist on the outer edge of the surface of the p-side electrode layer 16, it is possible to eliminate the strain of the metal thin film 15 which tends to concentrate at the end, and as a result Therefore, the stress due to the difference in linear expansion coefficient can be relaxed. That is, it is possible to protect the end face of the semiconductor laser device 9 which is relatively weak. Furthermore, since the metal thin film 15 does not contact the emitting end face of the semiconductor laser device 9, the emitting end face can be cleaved easily and reliably.

Next, each material and thickness for forming the p-side electrode layer 16, the metal thin film 15, the solder layer 14 and the metal thin film 13 will be described. FIG. 2 is an enlarged view of a joint portion between the semiconductor laser device 9 and the submount 12. In FIG. 2, the same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted here.

In FIG. 2, the p-side electrode layer 16 has a multi-layer structure in which a plurality of metal films are laminated, and at least the metal film which is in contact with the metal thin film 15 is formed containing Au. The p-side electrode layer 16 shown in the figure is, for example, five metal films a.
1 to a5. Note that these metal films may use the same material for other metal films as long as the materials of the adjacent metal films are different. For example, both the metal films a1 and a5 can be formed of Au.

The plurality of metal films are a combination of compositions capable of preventing deterioration due to electromigration between the metal films, and the total thickness thereof, that is, the thickness h4 of the p-side electrode layer 16 is the thermal resistance or the electrical resistance. It is preferable to form it so as to have a value that minimizes resistance. For example, the thickness h4 of the p-side electrode layer 16 is 0.5 μm or less.

The metal thin film 15 is formed by electrolytic plating using Au. In this way, the metal thin film 15 is
By forming the same metal as the outermost metal layer of the p-side electrode layer 16 from Au, it is possible to stably maintain the bonding state with the p-side electrode layer 16. Further, Au (particularly pure gold) is soft and has low electric resistance, and the film obtained by the electrolytic plating method has a rougher texture than that by the sputtering or vapor deposition method. You can make it work. That is, when fixing the semiconductor laser element 9 integrated with the metal thin film 15 onto the submount 12 via the solder layer 14,
It is possible to disperse the load of the semiconductor laser device 9 that is applied by the pressure applied to the submount 12 side. As a result, it is possible to prevent the semiconductor laser element 9 from being damaged when it is fixed. The thickness h3 of the metal thin film 15 is preferably set to a value that does not significantly increase thermal resistance or electric resistance while ensuring the cushioning function described above. Specifically, the thickness h3 of the metal thin film 15 is preferably at least 1 μm or more, and particularly preferably in the range of 2 to 9 μm. Further, the inventor has found that the optimum value of the thickness h3 of the metal thin film 15 is 6 μm in this range.

Here, as a method of manufacturing this semiconductor laser device, a step of forming a metal thin film 15 by electrolytic plating and then subjecting the metal thin film 15 to a heat treatment is included. By this heat treatment step, the grain size of Au forming the metal thin film 15 is increased, and the cushioning effect described above is enhanced.

The solder layer 14 serving as a conductive adhesive material is formed of Au-based material such as AuSn. In particular, since the Au-based material is soft and has a low electric resistance as described above, it can be thickened to have the same cushioning function as the metal thin film 15, and is suitable for strain relaxation. Also, the solder layer 14 is
Although the eutectic temperature changes depending on the composition of the material, if the eutectic temperature increases, that is, if the temperature difference up to cooling (normal temperature) is large, the difference in thermal expansion between the semiconductor laser element 9 and the submount 12 also becomes large, and the semiconductor The strain given to the laser element 9 also becomes large. Therefore, it is preferable to determine the composition of the solder layer 14 so that the eutectic temperature becomes low. For example, when AuSn is used as the solder layer 14,
It is preferable to set the ratio of Au: Sn = 74 to 80:26 to 20.

It is preferable that the thickness of the solder layer 14 is such that electric resistance and thermal resistance are minimized and a sufficient conductive function and adhesive function are fulfilled. For example, the solder layer 14
When AuSn is used as the material, 3.5 μm ± 20% in the coating state immediately before fixing the semiconductor laser element 9
(2.8 to 4.2 μm), and the thickness h2 after fixation is 1 μm.
It is about m.

The metal thin film 13 has a multi-layer structure in which a plurality of metal films are laminated, and is formed by including a metal film containing Au. The metal thin film 13 shown in the figure is constituted by four metal films c1 to c4, for example, and the metal film c3 is Au, for example. Note that these metal films may use the same material for other metal films as long as the materials of the adjacent metal films are different. For example, if the metal films c2 and c4 are both P
can be formed at t.

The plurality of metal films are a combination of compositions capable of preventing deterioration due to electromigration between the metal films, and the thickness of the metal film containing Au is calculated from the total thickness of the other metal films. Is also preferably formed so as to be large. For example, in the above example, the thickness of the metal film c3 is set to 2 μm, and the other metal films c1, c2 and c4 are used.
The total thickness is about 0.5 μm. As described above, also in the metal thin film 13, by using Au as the main material, it is possible to enjoy the advantages of the low electric resistance and the cushion function described above.

Although the thicknesses of the p-side electrode layer 16, the metal thin film 15, the solder layer 14 and the metal thin film 13 have been described above, the thicknesses of the p-side electrode layer 16, the metal thin film 15, the solder layer 14 and the metal thin film 13 are described. For the total hh of
The thickness is preferably in the range of 5 to 25 μm so that the heat dissipation effect of the submount 12 can be sufficiently brought out. In addition,
The n-side electrode layer 18 is also preferably configured by laminating a plurality of different metal films.

Further, in the junction down as shown in FIG. 2, the width h between the active layer 3 and the p-side electrode layer 16 is increased.
It is preferable that the number 5 is such that the effect of junction down, that is, the heat dissipation effect of the submount 12 is enjoyed and the influence of thermal strain is not exerted. Specifically, the inventor has found that the width h between the active layer 3 and the p-side electrode layer 16 is h.
It was found that the optimum value of 5 was 4 μm.

As described above, one of the parameters that affects the cushioning function of the metal thin film 15 is the grain size of the metal, and the cushioning function and the heat radiation effect between the semiconductor laser device 9 and the submount 12 are provided. In order to increase, the larger grain size is desirable.

FIG. 4 is a microscopic image of the metal thin film 15 when not subjected to any heat treatment (no sintering). Figure 4
As seen in, the grain size of the thin metal layer 15 is 2
It is much smaller than 0 μm. The present inventors conducted an experiment in the heat treatment step in order to know the relationship between the sintering temperature and the grain size of the metal thin film 15.

5 to 9 show the sintering temperature at 100 ° C.,
6 is a microscopic image showing the grain size of the metal thin film 15 at 200 ° C., 300 ° C., 360 ° C., and 420 ° C. Here, the grain size can be measured by drawing one straight line in a certain direction on the image. For example, in FIG. 9, a grain size can be obtained by drawing a straight line in the horizontal direction, counting the grains that intersect the straight line, and then dividing the length of the straight line by the number of grains.

As shown in FIGS. 5-9, as the sintering temperature increases, so does the grain size. Especially, when the sintering temperature is between 100 ° C. and 200 ° C., as shown in FIGS. 5 and 6, it can be clearly seen that the edge that determines the grain size is increased. In particular, as shown in FIG. 7, when the sintering temperature is 300 ° C., early crystallization is observed at the boundary of the metal thin film, and a larger grain size can be obtained. Further recrystallization is observed in FIGS. 8 and 9. From these results, the inventors have found that the metal thin film 1
To make the cushion function of 5 effective, 300 ° C
It has been found that heat treatment at the above sintering temperature is preferable.

10 and 11 are graphs for illustrating the sintering effect by the thermal stress of the semiconductor laser device.
In particular, FIG. 10 shows the relationship between the distance from the region of the active layer and the stress when the semiconductor laser device 10 is cooled from 325 ° C. to 25 ° C. without sintering the metal thin film 15. Further, FIG. 11 shows the relationship between the distance from the region of the active layer and the stress when the metal thin film 15 is sintered at 400 ° C. for 1 minute and then cooled under the same conditions as in FIG.

Further, FIGS. 10 and 11 include stress data when the thickness h3 of the metal thin film 15 is 1 μm and 6 μm, respectively. As shown in FIG. 10, without sintering, in the case of a semiconductor laser device in which the thickness h3 of the metal thin film 15 is 1 μm, the stress in its active region is 58.
212 MPa and the thickness h3 of the metal thin film 15 is 6 μm
In the case of the semiconductor laser device of, the stress in the active region is 5
It was 4.684 MPa. On the other hand, as shown in FIG. 11, with sintering, the thickness h3 of the metal thin film 15 is 1 μm.
In the case of the semiconductor laser device of, the stress in the active region is 5
5.55 MPa, the thickness h3 of the metal thin film 15 is 6μ
In the case of a semiconductor laser device of m, the stress in its active region is 4
It was 6.37 MPa. From these results, it was found that the stress at the center of the active region was reduced by the sintering treatment both when the thickness h3 of the metal thin film 15 was 1 μm and when it was 6 μm. This means that the grain size of the metal thin film 15 is brought into the state as shown in FIG. 9 by the sintering process, and the cushion function is more effectively exhibited.

Further, FIG. 10 shows the thickness h3 of the metal thin film 15.
Shows a simulation result of elastic deformation in the case of 1 μm and a case of 6 μm, and FIG. 11 also shows a simulation result of plastic deformation. That is, when the grain size is larger, the contribution of plastic deformation is larger and the stress is further reduced, but when the grain size is small, the stress is not reduced because the contribution of elastic deformation is large. When the thickness h3 of the metal thin film 15 is sufficiently large as 6 μm as in the present invention, the stress is 54.6884 MPa due to the sintering treatment.
To 46.27 MPa.

FIG. 12 is a graph showing the relationship between Vickers hardness and sintering temperature for gold materials. Note that FIG.
To obtain 2, each sample was measured at two points under the condition of holding a 10 gram load for 15 seconds. As seen in FIG. 12, the hardness decreases with increasing sintering temperature. From this result, above 300 ℃
It can be seen that at the above sintering temperature, the hardness of the metal thin film 15 becomes 65 HV or less.

FIG. 13 is a diagram showing the results of thermal shock tests of the semiconductor laser device according to the present embodiment and the conventional semiconductor laser device. Specifically, FIG.
3 (a), the thickness h3 of the metal thin film 15 is 6 μm 1
-40 ° C for 0 semiconductor laser device samples
It is a result of performing heating and cooling for 100 cycles between and 85 ° C. Further, FIG. 13B shows a metal thin film 15
The results are obtained by applying the same heat shock as in FIG. 13A to five samples of the semiconductor laser device having no.

As shown in FIGS. 13A and 13B, a semiconductor laser device having a metal thin film 15 containing a gold material is a semiconductor laser device having no such metal thin film 15. By comparison, it can be seen that the change width of the light output after the heat shock test is small. This means that the presence of the metal thin film 15 containing the gold material reduces the characteristic deterioration of the semiconductor laser device. That is, the semiconductor laser device according to the present embodiment has stable light output characteristics even after long-term use.

FIG. 14 is a flow chart showing the heat treatment (sintering) for the metal thin film 15. In FIG. 14, first, a semiconductor laser device is prepared after the formation of a p-side electrode layer, substrate polishing, and formation of an n-side electrode layer (step S1).
01). Then, on the p-side electrode layer of the semiconductor laser device, the metal thin film 15 as shown in FIG. 1B and FIG.
Are formed by electrolytic plating (step S102). In particular, the metal thin film 15 has a thickness of at least 1 μm, preferably 2 μm to 9 μm. Further, as described above, the metal thin film 15 may be composed of a plurality of metal thin films as long as at least one thin film contains a gold material.

Next, the semiconductor laser device having the metal thin film 15 formed thereon is heat-treated at a predetermined temperature for a predetermined time (step S103). This heat treatment is performed in a heating furnace that gradually heats from room temperature to a specific temperature, and is held at the specific temperature for several tens of seconds, for example. After being heated for a specific time in the heating furnace, it is cooled to room temperature (step S104). An apparatus other than the heating furnace may be used as long as the semiconductor laser apparatus can be heated.

After cooling, the metal thin film is formed with a large grain size and has an effective cushioning function as described above. Here, in the conventional method, the p-side electrode layer is formed and then sintered alone, and then the substrate is polished. Similarly, the n-side electrode layer is also independently sintered after being formed. And finally, all the elements are glued together to form a semiconductor laser device. On the other hand, in the present semiconductor laser device manufacturing method, since the metal thin film is sintered together with the p-side electrode layer and the n-side electrode layer which have not been sintered, the steps after the polishing of the substrate are performed. The number is decreasing than before. In other words, this method makes it possible to eliminate the step of sintering the p-side electrode layer and the n-side electrode layer independently.

As described above, according to the semiconductor laser device of the first embodiment, between the p-side electrode layer 16 of the semiconductor laser element 9 and the submount 12,
Since the metal thin film 15 is provided in the inner region separated from the end of the side electrode layer 16 by a predetermined width, it is possible to reduce the influence of thermal stress exerted on the end portion of the semiconductor laser device 9, and the active layer 3
It is possible to prevent the deterioration and damage of the semiconductor laser element 9 due to the heat generated in step 1 and the heat generated when the semiconductor laser element 9 is fixed on the submount 12.

The p-side electrode layer 1 of the semiconductor laser device 9
6, the metal thin film 15, the solder layer 14, and the metal thin film 13 on the submount 12 are arranged in that order, and each is formed by including an Au-based material, it is possible to give a cushioning effect to them. Therefore, the semiconductor laser element 9 can be protected when the semiconductor laser element 9 is pressed and fixed onto the submount 12. Also, A
Since the u-based material has low electric resistance and low thermal resistance, as a result, heat conduction from the semiconductor laser element 9 to the submount 12 can be improved, that is, the heat dissipation effect of the submount 12 can be maximized. It is possible to provide a stable and long-life semiconductor laser device.

In the first embodiment described above,
Although the junction down is shown as an example, the present invention can be similarly applied to a case where a so-called junction up structure is adopted in which the active layer 3 is provided on the upper electrode side by changing the polarity of the electrode. .

(Second Embodiment) Next, a semiconductor laser module according to a second embodiment will be described. The semiconductor laser module according to the second embodiment is a module of the semiconductor laser device shown in the first embodiment. FIG. 3 is a sectional view showing the structure of the semiconductor laser module according to the second embodiment. In FIG. 3, the semiconductor laser module 20 has a package 29 formed of a copper-tungsten alloy or the like as a housing. On the inner bottom surface of the package 29, the Peltier module 28 functioning as a temperature control device is arranged. A base 27 is arranged on the Peltier module 28, and a carrier 34 is arranged on the base 27.

In particular, in FIG. 3, the semiconductor laser device 31 corresponds to the semiconductor laser device shown in the first embodiment, and the carrier 34 corresponds to the carrier 11 shown in FIG. Therefore, the semiconductor laser device 31 is arranged on the carrier 34, but the thermistor 3 is further provided.
2 and the optical monitor 33 are arranged. Also, the base 27
The first lens 22 is arranged above. The laser light emitted from the semiconductor laser device 31 is guided into the optical fiber 25 via the first lens 22, the isolator 23, and the second lens 24. The second lens 24 is provided in the package 29 located on the optical axis of the laser light, and is optically coupled to the externally connected optical fiber 25. The optical monitor 33 monitors and detects the light leaked from the reflective film side of the semiconductor laser device 31.

Here, the semiconductor laser module 20
Then, the isolator 23 is interposed between the semiconductor laser device 31 and the optical fiber 25 so that the reflected return light from other optical components or the like is not re-entered into the resonator.

In the second embodiment described above, the semiconductor laser module has a configuration in which the laser light emitted from the semiconductor laser device 31 is output as it is, but it is provided near the end of the optical fiber 25 on the second lens 24 side. The present invention can also be applied to a semiconductor laser module with an optical fiber grating in which an optical fiber grating is formed and the laser light emitted from the semiconductor laser device 31 is wavelength-selected by this optical fiber grating and output. Especially in this case,
The isolator 23 is not provided.

As described above, according to the semiconductor laser module of the second embodiment, the semiconductor laser device shown in the first embodiment is mounted, so that the effects shown in the first embodiment are obtained. A semiconductor laser module can be provided.

[0071]

As described above, according to the semiconductor laser device of the present invention, the lower electrode layer of the semiconductor laser element, the metal thin film, the solder layer, and the metal thin film on the submount are arranged in that order. In addition, since each of them is formed by including an Au-based material, it is possible to provide a cushioning action, a low electric resistance and a low thermal resistance between the semiconductor laser device and the submount, thereby protecting the semiconductor laser device and radiating heat by the submount. It is possible to enjoy the effect and to provide a stable and long-life semiconductor laser device.

Further, according to the semiconductor laser device of the present invention, the metal thin film is formed in the inner region between the lower electrode of the semiconductor laser element and the submount, which is separated from the edge of the lower electrode layer by a predetermined width. Since it is provided, it is possible to reduce the effect of thermal strain on the end portion of the semiconductor laser device,
It is possible to prevent the deterioration of the semiconductor laser device and the damage due to the heat generated when the semiconductor laser device is fixed on the submount and the heat generated in the active layer.

Further, according to the semiconductor laser module of the present invention, since the above-mentioned semiconductor laser device is mounted, the effect of the above-described semiconductor laser device can be obtained.

Further, according to the method of manufacturing a semiconductor laser device of the present invention, after the metal thin film to be the buffer layer is formed on the semiconductor laser element, the metal thin film is subjected to heat treatment. The grain size of the constituent material can be increased, and the cushioning effect described above can be enhanced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a semiconductor laser device according to a first embodiment.

FIG. 2 is a perspective view of FIG. 1 (b).

FIG. 3 is an enlarged view of a joint portion between a semiconductor laser device and a submount.

FIG. 4 is a view showing a microscopic image of a metal thin film without sintering.

FIG. 5 is a view showing a microscopic image of a metal thin film when a sintering temperature is 100 ° C.

FIG. 6 is a view showing a microscopic image of a metal thin film when the sintering temperature is 200 ° C.

FIG. 7 is a view showing a microscopic image of a metal thin film when the sintering temperature is 300 ° C.

FIG. 8 is a view showing a microscopic image of a metal thin film when a sintering temperature is 360 ° C.

FIG. 9 is a view showing a microscopic image of a metal thin film when a sintering temperature is 420 ° C.

FIG. 10 is a graph showing the relationship between the distance from the region of the active layer and the stress for a metal thin film without sintering.

FIG. 11 is a graph showing a relationship between stress and a distance from a region of an active layer for a metal thin film with sintering.

FIG. 12 is a graph showing the relationship between Vickers hardness and sintering temperature for gold materials.

FIG. 13 is a graph showing a result of a thermal shock test of the semiconductor laser device according to the present embodiment and a conventional semiconductor laser device.

FIG. 14 is a flowchart showing heat treatment (sintering) for a metal thin film.

FIG. 15 is a sectional view showing a configuration of a semiconductor laser module according to a second embodiment.

FIG. 16 is a perspective view showing a schematic configuration of a conventional semiconductor laser device.

[Explanation of symbols]

3 Active layer 9,22,103 Semiconductor laser device 10, 31 Semiconductor laser device 11,34,101 carriers 12, 102, 104 submount 13, 15, 102a, 104a Metal thin film 14 Solder layer 16 p-side electrode layer 18 n-side electrode layer 20 Semiconductor laser module 22 First lens 23 Isolator 24 Second lens 25 optical fiber 27 base 28 Peltier module 29 packages 32,105 thermistor 33 Optical monitor 106a, 106b wire

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masayoshi Seki             2-6-1, Marunouchi, Chiyoda-ku, Tokyo             Kawa Electric Industry Co., Ltd. (72) Inventor Junji Yoshida             2-6-1, Marunouchi, Chiyoda-ku, Tokyo             Kawa Electric Industry Co., Ltd. F term (reference) 5F036 AA01 BA23 BB01 BB21 BC06                 5F073 BA02 BA03 CB23 EA24 EA28                       EA29 FA15 FA18 FA22

Claims (17)

[Claims] 1. A semiconductor laser device sandwiched by a first electrode layer and a second electrode layer for injecting a current into an active layer, a first metal thin film layer formed on a surface of the second electrode layer, A submount having insulation and high thermal conductivity and having a second metal thin film layer formed on the surface thereof; and a solder layer for joining the first metal thin film layer and the second metal thin film layer together. The second electrode layer, the first metal thin film layer, the solder layer, and the second metal thin film layer each contain Au as a main component, and the total thickness is 5 to 25 μm. apparatus. 2. A semiconductor laser device sandwiched between a first electrode layer and a second electrode layer for injecting a current into an active layer, a first metal thin film layer formed on a surface of the second electrode layer, A submount having insulation and high thermal conductivity and having a second metal thin film layer formed on the surface thereof; and a solder layer for joining the first metal thin film layer and the second metal thin film layer together. The semiconductor laser device, wherein the first metal thin film layer is formed in an inner region having an outer edge at a position inside a predetermined width from an end of the second electrode layer. 3. A semiconductor laser device sandwiched between a first electrode layer and a second electrode layer for injecting a current into an active layer, a first metal thin film layer formed on a surface of the second electrode layer, A submount having insulation and high thermal conductivity and having a second metal thin film layer formed on the surface thereof; and a solder layer for joining the first metal thin film layer and the second metal thin film layer together. A distance between the active layer and the second electrode layer is smaller than a distance between the active layer and the first electrode layer, and a distance that minimizes stress applied to the active layer due to thermal expansion. A semiconductor laser device characterized in that 4. A semiconductor laser device sandwiched between a first electrode layer and a second electrode layer for injecting a current into an active layer, a first metal thin film layer formed on a surface of the second electrode layer, A submount having insulation and high thermal conductivity and having a second metal thin film layer formed on the surface thereof; and a solder layer for joining the first metal thin film layer and the second metal thin film layer together. The second electrode layer, the first metal thin film layer, the solder layer, and the second metal thin film layer each have Au as a main component, and the total thickness is 5 to 25 μm. Is formed in an inner region having an outer edge at a position inside a predetermined width from the end of the second electrode layer. 5. A semiconductor laser device sandwiched between a first electrode layer and a second electrode layer for injecting a current into the active layer, a first metal thin film layer formed on the surface of the second electrode layer, A submount having insulation and high thermal conductivity and having a second metal thin film layer formed on the surface thereof; and a solder layer for joining the first metal thin film layer and the second metal thin film layer together. The second electrode layer, the first metal thin film layer, the solder layer, and the second metal thin film layer each contain Au as a main component, and the total thickness is 5 to 25 μm. The distance between the two electrode layers is smaller than the distance between the active layer and the first electrode layer and is a distance that minimizes the stress applied to the semiconductor laser element due to thermal expansion. Semiconductor laser device. 6. A semiconductor laser device sandwiched between a first electrode layer and a second electrode layer for injecting a current into an active layer, a first metal thin film layer formed on a surface of the second electrode layer, A submount having insulation and high thermal conductivity and having a second metal thin film layer formed on the surface thereof; and a solder layer for joining the first metal thin film layer and the second metal thin film layer together. The second electrode layer, the first metal thin film layer, the solder layer, and the second metal thin film layer each have Au as a main component, and the total thickness is 5 to 25 μm. Is formed in an inner region having an outer edge at a position inside a predetermined width from the end of the second electrode layer, and a distance between the active layer and the second electrode layer is equal to that of the active layer and the first electrode layer. The semiconductor laser is smaller than the distance between the electrode layer and the thermal expansion. A semiconductor laser device characterized by a distance that minimizes the stress applied to the element. 7. The second electrode layer is a multi-layer film composed of a plurality of metal films, and a metal film in contact with at least the first metal thin film layer of the plurality of metal films contains Au as a main component. The semiconductor laser device according to claim 1, wherein: 8. The semiconductor according to claim 1, wherein the first metal thin film layer is formed by an electrolytic plating method using Au as a main component and has a thickness of at least 1 μm. Laser device. 9. The first metal thin film layer is formed by an electrolytic plating method using Au as a main component and has a Vickers hardness of less than 65 at least.
7. The semiconductor laser device according to any one of 7. 10. The semiconductor laser device according to claim 1, wherein the first metal thin film layer has a planar shape having a convex portion at one of longitudinal end portions. . 11. The solder layer is a composition containing Au as a main component and having a eutectic temperature that minimizes strain applied to the semiconductor laser element due to thermal expansion. 10. The semiconductor laser device according to any one of items 10 to 10. 12. The solder layer comprises Au: Sn = 74-
The semiconductor laser device according to claim 11, wherein the semiconductor laser device is formed of AuSn having a composition ratio of 80:26 to 20. 13. The second metal thin film layer is a multi-layer film composed of a plurality of metal films, and at least one metal film of the plurality of metal films contains Au as a main component and the metal film. 13. The semiconductor laser device according to claim 1, wherein the semiconductor laser device has a thickness greater than a total thickness of other metal films. 14. The semiconductor laser device according to claim 1, wherein the submount is made of diamond. 15. The semiconductor laser device according to claim 1, wherein the cavity length is 800 μm or more. 16. A semiconductor laser device according to claim 1, a temperature measuring element for measuring a driving temperature of the semiconductor laser element, and a temperature output from the temperature measuring element. A temperature control element for controlling the temperature of the semiconductor laser device, wherein the submount is bonded above the temperature control element, and the temperature of the semiconductor laser device is controlled via the submount. Semiconductor laser module. 17. A step of forming a semiconductor laser element, a step of forming a metal thin film on a surface of the semiconductor laser element and on a side where the semiconductor laser element is fixed to a support, A method of manufacturing a semiconductor laser device, comprising: