JPH04286177A - Sub-mount for semiconductor laser - Google Patents

Abstract

PURPOSE:To inhibit the deterioration in the reliability of a semiconductor laser resulting from the difference of the thermal expansion coefficients of a sub- mount and a semiconductor laser. CONSTITUTION:A sub-mount 1a for a semiconductor laser, which has a first tabular member 11a composed of a material having small thermal expansion coefficient difference with a semiconductor laser 2 and a second tabular member 11b constituted of a diamond having excellent thermal conductivity and in which said first tabular member 11a and said second tabular member 11b are laminated so that the semiconductor laser 2 is mounted onto said first tabular member 11a, is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submount for a semiconductor laser. More specifically, the present invention relates to a submount for mounting a semiconductor laser, and in particular to a novel structure of a submount for a semiconductor laser that reduces thermal mismatch with the semiconductor laser.

0002

2. Description of the Related Art A semiconductor laser made of a compound semiconductor such as GaAs, which is a group III-V compound, generates heat during operation. Therefore, the device is mounted on a member called a submount for the purpose of improving its own heat dissipation and reducing the influence of heat on other elements that make up the device.

FIG. 2 is a sectional view showing the structure of a conventional general submount 1 and a semiconductor laser 2 mounted on the submount 1.

As shown in the figure, the submount 1 is composed of a plate member 11 having Au plating layers 12 on both sides. Known materials for the plate member 11 include diamond, Cu-W alloy, silicon, and the like.

On the other hand, the semiconductor laser 2 has a p-side electrode 21,
p-GaAs contact layer 22, n-type block layer 23,
P-type cladding layer 24, active layer 25, n-type cladding layer 26
, an n-type GaAs substrate 27 and an n-side electrode layer 28 are sequentially laminated.

The semiconductor laser 2 constructed as described above is fixed onto the submount 1 by hot pressure bonding.

[0007]

In the submount 1 used as shown in FIG. 2, the material of the plate member 11, which is the main member thereof, has the following characteristics.

That is, diamond is an extremely excellent material in that it has particularly excellent thermal conductivity and quickly diffuses the heat generated by the semiconductor laser 2. However, the coefficient of thermal expansion of diamond is significantly different from that of GaAs, which is the main material of the semiconductor laser 2. Therefore, when the semiconductor laser 2 is mounted on the submount 1 by hot press bonding, stress is generated due to thermal mismatch between the two, resulting in a problem that the reliability of the semiconductor laser 2 is deteriorated.

On the other hand, the thermal expansion coefficient of Cu-W alloy can be adjusted by adjusting the blending ratio of Cu and W.
s can be substantially equal to s. Therefore, even if the semiconductor laser is hot-pressed, the semiconductor laser will not be distorted. However, the thermal conductivity of the Cu-W alloy is far from that of diamond, and it still does not contribute to the reliability of semiconductor lasers in terms of poor heat dissipation.

[0010] As described above, in the conventional submount, there is a trade-off between its properties as a heat dissipation path and thermal mismatch, and an ideal submount has not yet been realized.

SUMMARY OF THE INVENTION Therefore, the present invention aims to solve the above-mentioned problems of the prior art and provide a novel submount that has a high thermal expansion coefficient matching with GaAs and also has excellent thermal conductivity. The purpose is

0012

[Means for Solving the Problems] That is, according to the present invention,
A semiconductor laser submount for mounting a semiconductor laser, the first plate member being made of a material having a coefficient of thermal expansion substantially equal to that of the semiconductor laser, and a diamond having excellent thermal conductivity. a second plate-like member, the first plate-like member and the second plate-like member being stacked on each other so that a semiconductor laser is mounted on the first plate-like member; A submount for a semiconductor laser is provided.

[0013]

[Operation] The submount according to the present invention includes a first plate-like member having a coefficient of thermal expansion substantially equal to that of a compound semiconductor such as GaAs, and a second plate-like member made of diamond having excellent heat dissipation properties. Its main feature is that it has a laminated structure.

[0014] In conventional submounts, the plate-like member, which is the main part, is made of a single material, so problems inherent to the material remain as problems with the submount.

In contrast, the submount according to the present invention includes a first plate member made of a material having the same coefficient of thermal expansion as that of the semiconductor laser, and a second plate member made of diamond having excellent thermal conductivity. The semiconductor laser is mounted on the first plate-like member.

Therefore, no thermal stress is applied to the semiconductor laser during hot press bonding, and the heat generated by the semiconductor laser during operation is efficiently diffused through the second plate member. In addition, the mismatch in thermal expansion coefficient between the first plate member and the second plate member is absorbed within the submount, which has a large bonding area, resulting in a submount with ideal characteristics. be done.

The submount according to the present invention constructed as described above can be handled in exactly the same way as a conventional submount, except that the mounting surface of the semiconductor laser is predefined.

Further, in view of the functions of each layer described above, the thickness of the first plate-like member may be within the range affected by hot press bonding, and the remaining thickness may be made entirely of diamond. desirable. Further, the first plate-like member and the second plate-like member can be joined using a known joining material such as Au or an Au-Sn alloy.

[0019] The present invention will now be described in more detail with reference to Examples, but the following disclosure is merely an example of the present invention and is not intended to limit the technical scope of the present invention in any way.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing a specific example of the structure of a submount 1a according to the present invention, with a semiconductor laser 2 mounted thereon. Note that the semiconductor laser 2 used here is exactly the same as the conventional semiconductor laser 2 shown in FIG. 2, so each component is given the same reference number as in FIG. 2, and the explanation thereof will be omitted. are doing.

As shown in FIG. 1, the submount 1a used here includes first and second plate members 11a and 11b, which are bonded together by a bonding material 13.
It is composed of Au plating layers 12 formed on the front and back sides thereof.

Here, the first plate member 11a is made of either a GaAs substrate 27 which is the material of the semiconductor laser 2, or a Cu substrate whose thermal expansion coefficient matches that of the p-GaAs contact layer 21 directly bonded to the submount 1. - Made of W alloy. Further, the second plate member 11b is made of diamond, which has extremely high thermal conductivity. Note that the joining member 1 that joins the first and second plate-like members 11a and 11b
3, Au-Sn (containing about 70% Au) is used, and both are bonded by hot press bonding.

[0023] Submount 1a configured as above
As shown in FIG. 1, the semiconductor laser 2 is mounted on a first plate member 11a made of a Cu-W alloy. As for the mounting method, it can be mounted by hot press bonding with the p-GaAs contact layer 21 facing down, similar to conventional submounts.

In this embodiment, the semiconductor laser 2 mounted on the submount 1a has the following width x depth x height.
Each semiconductor laser was 0.4 mm x 0.25 mm x 0.07 mm, and the submount had a width x depth of 0.75 mm x 0.75 mm. Further, the thickness of the first plate member 11a was 0.15 mm, and the thickness of the second plate member 11b was 0.2 mm. Furthermore, the material of the first plate member 11a had a Cu:W ratio of 10:90.

[0025] Submount 1a configured as above
The mounting surface side is Cu-W, which has the same coefficient of thermal expansion as GaAs.
Since it is made of an alloy plate-like member, thermal stress is not generated in the semiconductor laser 2 when the semiconductor laser 2 is hot-pressed, and it acts on the active layer 25, which has the most profound effect on the characteristics of the semiconductor laser. It is possible to eliminate the thermal stress caused by Moreover, since most parts of the submount 1a are made of diamond, which has excellent thermal conductivity, the heat generated by the semiconductor laser 2 is quickly conducted to the stem via the submount 1a.

[0026]

As explained above, in the submount according to the present invention, the mounting surface side of the semiconductor laser is made of a material having the same coefficient of thermal expansion as that of the semiconductor laser, and thermal stress is applied to the semiconductor laser by hot pressure bonding. It never works. On the other hand, the side opposite to the mounting surface is made of diamond, which has excellent thermal conductivity, and has the function of quickly diffusing the heat generated by the semiconductor laser.

[0027] Therefore, the semiconductor laser is not distorted during bonding, and the heat dissipation property during high-output operation is excellent, so that the reliability of the semiconductor laser is significantly improved.

The semiconductor laser submount according to the present invention can be particularly advantageously used in fields where a semiconductor laser is used in a high output operating state and high reliability is required.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a specific configuration example of a submount according to the present invention in a state where a semiconductor laser is mounted.

FIG. 2 is a cross-sectional view showing a typical configuration of a conventional submount with a semiconductor laser mounted thereon.

[Explanation of symbols]

1 submount, 11 plate member, 11a plate member (Cu-W alloy), 11b
Plate member (diamond), 12 Au plating layer, 13 bonding material, 2 semiconductor laser, 21 p-side electrode, 22 p-GaAs contact layer, 23
n-type block layer, 24 p-type cladding layer, 25 active layer, 26 n-type cladding layer, 27 n-type GaAs substrate, 28 and n-side electrode layer

Claims (1)

[Claims] 1. A semiconductor laser submount for mounting a semiconductor laser, comprising: a first plate member made of a material having a coefficient of thermal expansion substantially equal to that of the semiconductor laser; and a first plate member having excellent thermal conductivity. a second plate-like member made of diamond; the first plate-like member and the second plate-like member are arranged such that a semiconductor laser is mounted on the first plate-like member; A submount for a semiconductor laser, characterized by being made by laminating two layers on each other.