JPH04314375A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To improve heat dissipation effect of a semiconductor laser element, to realize compactness of a light emission part and to improve freedom of packaging. CONSTITUTION:A pair of Cu electrodes which supply a current to a semiconductor laser element 6 are made to also function as a conventional heat sink. That is, cross sectional contour of a P-side electrode 1 and an N-side electrode 2 which hold the semiconductor laser element 6 between is made hollow brush type, and through-holes 1a, 2a are provided to one thick end part which contact- supports the semiconductor laser element 6 to circulate cooling medium such as air and water. The other end part is formed thin as elastic supporting parts 1b, 2b and it is insulation-supported mutually by an insulating spacer 7 and relaxes a stress caused by heat generation. The P-type electrode alone can be made hollow brush type and an N-type electrode can be made Cu block, etc., as before. In this case, an active region 4 can be faced to any electrode side.

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 more particularly to a semiconductor laser device that has excellent heat dissipation effects, has a large degree of freedom in mounting, and allows for miniaturization of the light emitting section.

0002

2. Description of the Related Art In semiconductor laser device mounting technology, absorption and release of Joule heat generated during operation, and temperature control of a light emitting section based on these factors are extremely important issues. This is because if the temperature rise at the pn junction when the semiconductor laser element is energized exceeds a predetermined allowable range, characteristics such as optical output and oscillation wavelength will change, and the life of the element will be shortened.

Since a semiconductor laser device emits optical power from the cleavage plane, which is the side surface of the chip, heat absorption and heat radiation are performed through the upper and lower surfaces (hereinafter referred to as principal surfaces) sandwiching the cleavage plane. For this purpose, the main surface of the chip may be directly connected to the package body, but generally speaking, it has excellent thermal conductivity.
A heat sink is formed using a submount material whose coefficient of thermal expansion is close to that of the chip and has excellent workability, and the main surface of the chip is connected to the heat sink via a solder material that enables ohmic connection. are doing. The connection method used in this case is junction down, in which the active region where the current concentrates is placed close to the heat sink.
n down method and junction up method where the active region is located remotely from the heat sink.
n up) method. Of these, junction
Although the down method requires soldering near the pn junction, making assembly difficult, it has excellent heat dissipation characteristics. Therefore, when mounting a semiconductor laser device having high output such as an array type laser used as a head of a laser printer, the junction down method is an essential requirement.

[0004] Furthermore, various attempts have been made to improve the heat dissipation effect of the heat sink, such as connecting water-cooled or air-cooled fins to the heat sink, and Techniques such as arranging a water cooling tube inside or performing cooling and temperature control using a Peltier element are known.

[0005] Alternatively, the applicant of the present application may have previously applied for
As disclosed in Publication No. 3356, a semiconductor laser element is sandwiched between two heat sinks on both main surfaces thereof, and these heat sinks are both supported on the same substrate, thereby significantly increasing the heat dissipation effect. There is also a laser device. This has the configuration shown in FIG. 4, for example, in which a semiconductor laser element 29 is soldered to a first heat sink 26 and a second heat sink 32, each of which has metallized layers 27 and 33 deposited on its surface in advance. The first heat sink 26 is sandwiched between layers 30 and 34, and the first heat sink 26 is sandwiched between a conductive material layer 35 and a solder layer 36. It is connected and fixed to a substrate 21 consisting of. The substrate 21 is provided with a ground pin 23 and a conductive pin 25. The conductive pin 22 is
It is inserted into a conductive pin holding hole 22 bored in the substrate 21,
It is fixed via an insulating spacer 24. The conductive pin 25 and the metallized layer 33 on the surface of the second heat sink 32 are connected to the connection line 3 by wire bonding.
7, and thereby the semiconductor laser element 29 can be energized. The active layer 31 of the semiconductor laser element 29 is arranged close to the first heat sink 26, which has a large volume and a high cooling capacity. According to this configuration, the Joule heat generated from the semiconductor laser element 29 is transferred from both principal surfaces to the two heat sinks 2.
6, 32 to the substrate 21, and further the substrate 2
Since the heat is radiated from 1 to the atmosphere, an excellent heat radiating effect can be obtained. Furthermore, since wire bonding is not performed directly to the chip of the semiconductor laser element 29,
No local stress is applied to the element.

[0006]

[Problems to be Solved by the Invention] However, in semiconductor laser devices that have a high output of 10 W class, which have been developed in recent years, the amount of heat generated during operation has increased dramatically, and the conventional heat - There is a limit to the cooling capacity of sink cooling methods. Furthermore, although the junction-down method is essential in mounting high-power semiconductor laser devices, there are cases where the degree of freedom in electrode configuration is impaired. According to the technology previously proposed by the applicant of the present application, the heat dissipation effect has been significantly improved and the original objective has been achieved, but further miniaturization is desired in order to increase the degree of freedom in packaging. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor laser device that has excellent heat dissipation effects, has a large degree of freedom in assembly, and can be miniaturized.

[0007]

[Means for Solving the Problems] A semiconductor laser device of the present invention is proposed to achieve the above-mentioned object, and consists of a pair of semiconductor laser devices that sandwich a semiconductor laser device in order to supply current to the semiconductor laser device. A semiconductor laser device is provided with an electrode, wherein at least one of the pair of electrodes has a relatively large thickness at one end portion that contacts and supports the semiconductor laser element. A through hole is drilled to enable cooling of the
Moreover, the thickness is relatively small at the other end.

[0008]

In the semiconductor laser device of the present invention, by devising the shape of the current-carrying electrode, it is possible to impart a cooling function to the electrode itself and to alleviate stress caused by heat generation. That is, one end of the electrode has a relatively large thickness, thereby providing sufficient mechanical strength to support the semiconductor laser element. In addition, a through hole is bored in this part, and by circulating an appropriate cooling medium such as water or air through the through hole, it is possible to cool the semiconductor laser element placed close to this hole. There is. Further, the other end of the electrode has a relatively small thickness, so that it is given appropriate elasticity, and stress generated by heat generation can be alleviated. Hereinafter, in this specification, the configuration of this electrode will be expressed as a "hollow brush type" due to the characteristics of its cross-sectional shape.

The object of the present invention can be achieved if such a configuration is adopted for at least one of the pair of electrodes that sandwich the semiconductor laser element, that is, the p-side electrode and the n-side electrode. That is, if only one electrode has a hollow brush type configuration, the other electrode may be a conventional heat sink, but if both main surfaces of the semiconductor laser element are Compared to the case where the light emitting part is held between heat sinks, the size of the light emitting part is significantly reduced. In this case, the cooling by the electrodes may be considered to supplement the cooling capacity of the heat sink. Also,
When both electrodes have a hollow brush type configuration, not only an excellent cooling effect can be obtained, but also a significant reduction in size compared to any conventional technology is possible. In any case, according to the present invention, the degree of freedom in implementation is improved because it does not matter whether the junction down method or the junction up method is used. Further, since wire bonding is not performed directly to the chip of the semiconductor laser element, no local stress is applied to the active region, and bulk deterioration such as dark line defects can be avoided.

0010

[Examples] Specific examples of the present invention will be described below.

Example 1 In this example, the present invention is applied to a collectively driven array type semiconductor laser device used in a laser printer head, etc., and both of a pair of electrodes that sandwich a semiconductor laser element are hollow. This is an example of a brush type configuration. This semiconductor laser device will be explained with reference to FIG. In this device, a long semiconductor laser element 6 has a pair of copper (
Cu) electrode, that is, the p-side electrode 1 and the n-side electrode 2 are sandwiched at one end. The cross-sectional shapes of the p-side electrode 1 and the n-side electrode 2 are similar to each other in the form of a hollow brush, and the thickness is increased at the portion that contacts and supports the semiconductor laser element 6, and through holes 1a and 2a are formed therein, respectively. ing. The contact surface between the p-type cladding layer 5 of the semiconductor laser element 6 and the p-side electrode 1, and the contact surface between the n-type cladding layer 3 and the n
A solder layer (not shown) is formed on each contact surface with the side electrode 2 to enable ohmic connection between metal and semiconductor. In the example shown in FIG. 1, the solder layer is formed in stripes at least on the surface of the p-side electrode 1 in order to limit the laser oscillation site in the active region 4. The through holes 1a and 2a contain water,
A suitable cooling medium such as air is
circulated in the direction. The other ends of both electrodes 1 and 2 are thin elastic support parts 1b and 2b, respectively, which are electrically insulated from each other by insulating spacers 7 and are mechanically held together. Further, a photodetector 8 for output monitoring is provided on the surface of the insulating spacer 7 facing the cleavage surface of the semiconductor laser element 6.

In the semiconductor laser device constructed as described above, the heat dissipation effect is significantly improved compared to the conventional device, and the light emitting section is also miniaturized. That is, since the p-type electrode 1 and the n-side electrode 2 are electrodes that supply current to the semiconductor laser element 6 and are also good conductors of heat, a cooling medium is circulated inside both electrodes 1 and 2. With this configuration, Joule heat generated as the semiconductor laser element 6 operates is rapidly exchanged. In addition, by reducing the thickness of the other end of both electrodes 1 and 2, the electrode 1
, 2 has a larger surface area, and the heat dissipation effect from its own surface is improved. Moreover, since the other end is made thinner and has appropriate elasticity, the stress generated due to heat generation is alleviated in this thinner portion, that is, the elastic support portions 1b and 2b. Therefore, deterioration of the controllability, response speed, life span, etc. of the semiconductor laser element 6 can be prevented. Furthermore, in the configuration in which the p-side electrode 1 and the n-side electrode 2 are directly connected to the semiconductor laser device 6, there is no need to perform wire bonding to the cladding layer that constitutes the semiconductor laser device 6, so that the active region No local stress is applied to 4, and there is no concern that defects will be induced. For example, if a thermistor is provided on the outer surface of the p-side electrode 1, temperature monitoring becomes possible.

Embodiment 2 This embodiment is an example in which the present invention is applied to a selective drive type array type semiconductor laser device, and both of a pair of electrodes that sandwich a semiconductor laser element have a hollow brush type structure. It is. This semiconductor laser device will be explained with reference to FIG. Note that in FIG. 2, parts common to those in FIG. 1 are given the same numbers and will be explained. In this example, in order to enable selective driving, the active regions of the semiconductor laser element are separated by grooves, and in order to make the p-side electrode correspond to these active regions, Cu electrode layers and insulating layers are alternately formed. It has a laminated cladding structure. That is, the p-side electrode 1 of Example 1
In this embodiment, a portion corresponding to the p-side electrode structure 12 is defined as the p-side electrode structure 12. This p-side electrode structure 12 includes a plurality of Cu electrode layers 10 for supplying current to the semiconductor laser element 16.
A laminate in which a plurality of Cu electrode layers 10 and an insulating layer 11 for insulating each other from each other are laminated alternately is processed so that the cross-sectional shape becomes a hollow brush type. The insulating layer 11 is made of a material that is a good thermal conductor and has a coefficient of thermal expansion similar to the constituent materials of the Cu electrode layer 10 and the semiconductor laser element 16. The above p-side electrode structure 1
A through hole 12a is formed at one end of the semiconductor laser element 2 that contacts and supports the semiconductor laser element 16, and a cooling medium is circulated through the hole 12a in the direction of arrow C in the figure. Also,
The other end, which does not contact and support the semiconductor laser element 16, is formed thin and serves as an elastic support portion 12b. On the other hand, grooves 17 are formed in the semiconductor laser element 16 in order to limit individual laser oscillation regions in the active region 14 . When connecting the semiconductor laser element 16 and the p-side electrode structure 12, a solder layer is formed on the surface of the Cu electrode layer 10 to achieve an ohmic connection, and the Cu electrode 10
and p-type cladding layer 15 are placed in contact with each other, and groove 17 and insulating layer 11 are placed in contact with each other. The n-side electrode 2 is a common electrode. In this example, as in Example 1, excellent heat dissipation effects and miniaturization were achieved.

Embodiment 3 In this embodiment, the present invention is applied to a selective drive type array type semiconductor laser device, and of a pair of electrodes that sandwich a semiconductor laser element, only the p-side electrode is of a hollow brush type. In this example, the side electrodes are constructed from conventionally used block-shaped heat sinks. This semiconductor laser device will be explained with reference to FIG. In addition, in Figure 3, Figure 2
The same parts are given the same numbers and explained. The configurations of the semiconductor laser element 16 and the p-side electrode structure 12 in this embodiment are the same as those described in the second embodiment. In this embodiment, a heat sink 18 made of a Cu block was used as the n-side common electrode. As is conventionally done, the heat sink 18 is provided with a through hole 18a just below the portion that contacts and supports the semiconductor laser element 16, and a cooling medium is inserted into the hole 18a in the direction of arrow D in the figure. The semiconductor laser element 16 is cooled by circulating the semiconductor laser element 16. Conventionally, when a high-output semiconductor laser device is supported in contact with a block-shaped heat sink, mounting using the junction-down method has been essential. However, as in this example, p
If cooling is also possible from the side electrode structure 12, mounting by the junction-up method as shown in FIG. 3 becomes possible, and the degree of freedom in mounting increases. In the case of this embodiment, as a method of cooling the heat sink 18, a Peltier element or the like may be used instead of circulating a cooling medium.

[0015]

As is clear from the above description, the semiconductor laser device of the present invention has a structure in which at least one of the current-carrying electrodes is of a hollow brush type, and cooling is performed from both principal surfaces of the semiconductor laser element. It is said that Therefore, the heat dissipation effect is significantly improved compared to conventional semiconductor laser devices, and the controllability, high-speed response, lifespan, etc. of the semiconductor laser device are significantly improved. Furthermore, the light emitting section is miniaturized and the degree of freedom in mounting is improved. Therefore, the present invention is extremely effective particularly in mounting array-type semiconductor laser devices and the like having high output.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing a configuration example of a collectively driven array type semiconductor laser device to which the present invention is applied.

FIG. 2 is a schematic perspective view showing a configuration example of a selectively driven array type semiconductor laser device to which the present invention is applied.

FIG. 3 is a schematic perspective view showing another configuration example of a selectively driven array type semiconductor laser device to which the present invention is applied.

FIG. 4 is a schematic cross-sectional view showing a configuration example of a conventional semiconductor laser device.

[Explanation of symbols]

Claims (1)

[Claims] 1. A semiconductor laser device comprising a pair of electrodes sandwiching a semiconductor laser element in order to supply current to the semiconductor laser element, wherein at least one of the pair of electrodes is connected to the semiconductor laser element. The thickness is relatively large at one end that contacts and supports the laser element, and a through hole is formed to allow cooling of the semiconductor laser element, and the thickness is relatively small at the other end. A semiconductor laser device characterized by: