JPH04293287A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To improve heat dissipation and productivity by composing a heat sink provided between a semiconductor laser element and a metal block of Si or Mo series, and forming a thin film on a surface of the block or the element. CONSTITUTION:Since a heat sink 11 made of a thin film is formed on a surface 12 of a metal block 7 or a surface 19 of a semiconductor laser element 1 thereby to form the sink 11 thin, its heat resistance value is reduced, and a temperature rise of the element 1 is reduced. Further, since a material of Si or Mo series of the material of the sink 11 has substantially the same thermal expansion coefficient as that of the element 1, its thermal stress distortion is small, and a material of Si series and particularly an amorphous Si is easily formed as a film at a relatively low temperature. Thus, heat dissipating and productivity are improved.

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 with good heat dissipation and productivity.

0002

2. Description of the Related Art In recent years, many improvements have been made to semiconductor laser devices having good heat dissipation properties. Among them, for example,
A semiconductor laser device disclosed in Japanese Unexamined Patent Publication No. 1-138777 is shown in FIG. In this figure, 41 is the stem 42
This is a metal block made of Cu fixed to the surface of the metal via Ag paste. Reference numeral 43 denotes a submount consisting of a Si block with a layer thickness of 300 μm, and bonding electrodes 44 were formed on both sides of the submount. 45 is a semiconductor laser element fixed to the surface of the bonding electrode 44. By selecting the material for the bonding electrode 44, the heat dissipation performance has been improved.

0003

However, the thermal resistance value of the above-mentioned semiconductor laser device was 50°C/watt, and the temperature rise value of the semiconductor laser element 45 was 10°C. Due to this high temperature increase value, the semiconductor laser element 45 began to deteriorate after 3000 hours of continuous testing at room temperature and rated output. In order to cope with this problem, a semiconductor laser device in which the submount 43 was experimentally made thinner had a smaller thermal resistance value and better heat dissipation. However, since the thin submount 43 is handled during manufacturing, it is easily broken, and it has been impossible to mass-produce the submount 43 with a thickness of 250 μm or less. The present invention has been made in view of the above-mentioned drawbacks, and is intended to provide a semiconductor laser device with good heat dissipation and high productivity.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention fixes a metal block to the surface of the stem,
A heat sink is provided between the metal block and the semiconductor laser element. The heat sink is made of a Si-based or Mo-based material and is a thin film formed on the surface of the metal block or the surface of the semiconductor laser element.

[0005]

[Operation] Since the present invention forms a thin film on the surface of the metal block or the surface of the semiconductor laser element, the thickness of the film can be reduced, resulting in a small thermal resistance value. Furthermore, since a thin film is formed, the thin film is not handled during manufacturing, so there is no cracking and productivity is good.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to a sectional view of FIG. 1, a sectional view of a main part of FIG. 2, and an exploded perspective view of FIG. 1 is a semiconductor laser element, and from the outside, a back electrode 2
, a first layer 3, an active layer 4, a second layer 5, and an electrode 6. Both the back electrode 2 and the electrode 6 are made of Au or the like, and have a layer thickness of 1 μm. The first layer 3 is composed of, in order from the outside, a semiconductor substrate, a current injection layer, and a first cladding layer, and has a total layer thickness of 80 μm. Active layer 4 is Ga0.95Al0
．． The layer thickness is 0.1 μm. The second layer 5 consists of a second cladding layer and a cap layer, and has a layer thickness of 11 μm. A metal block 7 is composed of a Cu block 8 made of Cu, and a Sn layer 9 and an Au layer 10 successively formed on the surface thereof by plating.

Reference numeral 11 denotes a heat sink consisting of a thin film formed on the surface 12 of a metal block by vapor phase growth. The material of the thin film of this heat sink 11 is selected from materials with high thermal conductivity. In other words, the thermal conductivity is 1.45 of Si.
watt/cm・℃ is preferably equal to or higher than that, and materials that satisfy this condition include polycrystalline Si, amorphous Si,
There are Mo etc. In this example, amorphous Si was used as the material for the thin film. A specific method for manufacturing the heat sink 11 will be described below. After installing the metal block 7 in the reactor and evacuating the reactor, the raw material gas Si
H4 is introduced into the reactor. In this state, high-frequency waves are applied to the electrodes in the reactor to generate high-frequency discharge. This allows SiH
4 is decomposed and amorphous Si is deposited on the surface of the metal block 7. The temperature of Cu block 7 at this time is 20
The temperature is maintained between 0 and 300°C. In this embodiment, the above-mentioned plasma CVD method is used, but other methods include sputtering, photo-CVD, and thermal CVD, and the vapor phase growth method is selected from among these methods.

Reference numeral 13 denotes a bonding electrode provided on the surface 14 of the heat sink by sputtering or the like. The bonding electrode 13 includes, in order from the side closest to the surface 14 of the heat sink, a first Au layer 15 with a layer thickness of 0.03 μm;
A Pt layer 16 with a layer thickness of 0.03 μm, a second layer with a layer thickness of 1.5 μm
It is composed of an Au layer 17 and an In layer 18 with a thickness of 3 μm. The surface 19 of the semiconductor laser element is placed and fixed on the surface of the bonding electrode 13. A stem 20 is made of a metal material, and has a first lead 22 and a second lead 23 with an insulator 21 in between, and a third lead 24. A photodiode 25 for monitoring the laser beam and a metal block 7 are fixed to the surface 26 of the stem via Ag paste 27, respectively. After the wiring process is completed, the cap 28 is fixed to the stem 20.

Next, referring to FIG. 4, the relationship between the layer thickness of the heat sink or submount and the thermal resistance value in the semiconductor laser device according to this embodiment and the prior art is shown. In this figure, the horizontal axis indicates the layer thickness on a logarithmic scale, and the unit is μm. The vertical axis indicates the thermal resistance value, and the unit is °C/watt. The circles indicate the measured thermal resistance values for the heat sink layer thicknesses of 1, 5, 10, and 20 μm in the semiconductor laser device according to this example. The △ mark is the method described in the prior art, that is, various layer thicknesses of amorphous Si (30, 100, 300
The measured thermal resistance values of semiconductor laser devices using block-shaped submounts (μm) are shown. The experimental results revealed that the slope of the thermal resistance value is gentle when the submount layer thickness is 10 μm or less, and becomes steep when the layer thickness exceeds 10 μm. Therefore, the conventional device uses a silicon submount with a layer thickness of 300 μm, so the thermal resistance value is 50 μm.
℃/watt, but if an amorphous Si thin film with a layer thickness of 10 μm is used in this example, the thermal resistance value will be 18℃/watt.
It becomes watt. Therefore, the temperature increase value of the semiconductor laser device 1 according to this embodiment is 10° C.×18/50=3.6° C., which can be reduced to 36% of the conventional temperature. Further, in this embodiment, the heat sink 11 is connected to the surface 12 of the metal block.
However, even if it is formed on the surface 19 of the semiconductor laser element, the thermal resistance value will be similarly small, and the heat dissipation will be similarly good. Furthermore, although amorphous Si is used as the material for the heat sink 11 in this embodiment, polycrystalline Si may also be used. However, in order to form a thin film made of polycrystalline Si by vapor phase growth, it is necessary to grow the metal block 7 in an atmosphere of about 900°C in the above manufacturing method.
As a result, productivity is slightly lower than that of amorphous Si.

Next, a second embodiment of the present invention will be described with reference to a cross-sectional view of the main part of FIG. In this figure, parts that are the same as those in the first embodiment are designated by the same numbers. 29 is the surface 1 of the metal block
2 is a bonding electrode formed by a sputtering method or the like. The bonding electrode 29 is composed of an In layer 30 with a thickness of 3 μm and an Au layer 31 with a thickness of 0.2 μm, in order from the side closer to the surface 12 of the metal block. A heat sink 32 is a thin film formed on the surface 19 of the semiconductor laser element by sputtering. The material of this heat sink 32 is Mo. The semiconductor laser element 1 having the heat sink 32 has a bonding electrode 2.
It is placed and fixed on the surface of 9. The thermal conductivity of Mo is S
Since it was approximately equal to i, the thermal resistance value and heat dissipation showed good values that were approximately equivalent to those of the first embodiment described above. This embodiment also has good productivity because the thin film is not handled during manufacturing. In addition, the thermal expansion coefficient of Mo is similar to that of Si-based materials in the semiconductor laser device 1.
Since the coefficient of thermal expansion is approximately the same as that of , thermal stress distortion is unlikely to occur like Si-based materials. For example, M with a layer thickness of 0.5 μm
In the semiconductor laser device of this example using the thin film of 0.0, the semiconductor laser element 1 did not deteriorate after 7500 hours at room temperature and rated output. This experimental result proved that no thermal stress distortion occurred. Furthermore, in this embodiment, the In layer 3 in the semiconductor laser element 1 and the bonding electrode 29 is
A heat sink 32 made of Mo is provided between the two. Therefore, the semiconductor laser device 1 due to the precipitation of the In layer 30
Defect induction is prevented by Mo.

[0011]

According to the present invention, heat sinks 11 and 32 made of thin films are formed on the surface 12 of a metal block or the surface 19 of a semiconductor laser element. As a result, the heat sink 11,
32 can be formed thinly, the thermal resistance value is reduced, heat dissipation is improved, and the temperature rise value of the semiconductor laser element 1 is reduced. Also, since it forms a thin film, it is not handled during manufacturing, so there is no cracking and productivity is improved. Furthermore, since the Mo or Si-based material of the heat sinks 11 and 32 has substantially the same coefficient of thermal expansion as the semiconductor laser element 1, thermal stress distortion is small and the life span is extended to 7,500 hours or more. Furthermore, Si-based materials, particularly amorphous Si, can be easily formed into a film at a relatively low temperature, so productivity is improved. By providing a heat sink 32 made of Mo between the semiconductor laser element 1 and the In layer 30, it is possible to prevent defects in the semiconductor laser element 1 due to precipitation of the In layer 30.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 3 is an exploded perspective view of a semiconductor laser device according to a first embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the layer thickness of the heat sink or submount and the thermal resistance value in the semiconductor laser device according to the first embodiment of the present invention and the conventional technology.

FIG. 5 is a sectional view of a main part of a semiconductor laser device according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view of a conventional semiconductor laser device.

[Explanation of symbols]

1 Semiconductor laser element 7 Metal block 11 Heat sink 32 Heat sink 12 Surface of metal block 19 Surface of semiconductor laser element 20 Stem

Claims (1)

[Claims] 1. A semiconductor laser device comprising a stem, a metal block fixed to the surface of the stem, a semiconductor laser element, and a heat sink provided between the semiconductor laser element and the metal block. The semiconductor laser device is characterized in that the heat sink is made of a Si-based or Mo-based material and is a thin film formed on the surface of the metal block or the surface of the semiconductor laser element.