JPS6052079A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To lessen rise of the heat resistance and the series resistance as well as to upgrade the processing precision by a method wherein a semiconductor laser chip is bonded to a Cu heat sink through an Si submount. CONSTITUTION:Sn 7 is evaporated on the surface of an Si wafer 1 after Ni/Ag were evaporated thereon, and following that, Au 8 is evaporated. A semiconductor laser chip 12 is bonded on each of individual submounts obtained by performing a dicing processing on the wafer 1 and the submount is bonded on a Cu heat sink 9 performed a gold plating of Au. According to such as way, rise of the heat resistance and the series resistance can be lessened, and at the same time, the processing precision can be upgraded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a semiconductor laser device used in optical communication, optical information processing, etc.

Conventional Structure and Point I In recent years, semiconductor lasers have reached the level of practical use and are being applied to various fields due to their small size, light weight, and high efficiency.

By the way, the size of a semiconductor laser is 0.3×O
, 3X O, 1wn, and although it has higher efficiency than other lasers, unless the heat generated during laser oscillation is efficiently dissipated, the heat generation will significantly impair reliability. Therefore, it is necessary to bond to the heat sink so that the thermal resistance is as small as possible. For this purpose, bonding is usually performed with the substrate side facing up and the epitaxial growth side facing down. To minimize thermal resistance, solder the semiconductor laser chip directly to C.
u It is best to bond to the heat sink, but
This is disadvantageous for mass production.

Therefore, in the past, Cuf was used for the submount. C
If u submount) k is used, the increase in thermal resistance will be small, but the machining accuracy will not improve and the coefficient of thermal expansion is higher than that of GaAs.
(6,9X 10-6/'C) and Cu (1,4X1
0-5/°C), so a hard solder such as Sn cannot be used, and a soft solder such as In must be used. However, when used as Inf solder, the chip may move due to its low melting point (156° C.), resulting in a lack of reliability.

Purpose of the Invention In view of the above drawbacks, the present invention provides a submount material that is easier to process than a Cu submount, has better processing accuracy, has a coefficient of thermal expansion close to that of GaAs, and has a thermal conductivity that is not so bad as compared to Cu. It is.

Structure of the Invention In order to achieve all of these objects, the submount of the present invention is made of Si.
f is used, and Si has a thermal expansion coefficient of 2.4X10
/rr, so the GaAs laser chip can be bonded using Sn f, improving reliability.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a Si wafer used for a submount. sb Doped n-type with (1ω) plane, thickness 200-500 μm 1 Specific resistance (ρ) 0.7-1.8
On both sides of the X10-2 Ωcm wafer, the substrate heating temperature was 20
Cr3'160 at 0℃, vacuum level 2X10 Torr or less
0 people, Ni - Cr 4 f 500 people, followed by 3000 people NiS, 3000 people vaporizing Ag6.

In order to use Sn for bonding with the semiconductor laser chip, Sn 7 f was evaporated to a thickness of 1.871 m on the surface of the Si wafer 1 after Ni/Ag evaporation, and then A
u8f: Deposit 0.2 μm (Au flash).

The purpose of Au 8 is to prevent oxidation of the Sn 7 surface. The deposition conditions were a substrate temperature of room temperature and a degree of vacuum of 5 x 10-6To.
rr or less.

This Si wafer i1. Dice it into OX1.2mm square pieces to make individual submounts. FIG. 2 shows how the semiconductor laser chip 12 is bonded to the submount and then dented onto the Au-plated Cu heat sink 9 using the submount iIn solder.

The thinner the Si submount is, the better it is in terms of thermal resistance, but it becomes more difficult to handle. Therefore, the thickness of the submount must be determined based on thermal resistance and electrical resistance. Figure 3 shows the size of 1.0 mm Xl, 2M, and the specific resistance is 0.01.
Figure 4 shows the relationship between the submount thickness and the electrical resistance (R). From Figure 3, even if a 500 μm thick submount is used, the temperature will reach 50'C/
It can be used with a thermal resistance on the order of W, and it can be seen from FIG. 4 that the increase in series resistance can be suppressed to 0.16Ω or less, so that the St 2 submount of the present invention can be fully put to practical use.

Effects of the Invention As described above, the present invention uses a Si submount to bond the semiconductor laser chip upside down, thereby reducing the increase in thermal resistance and series resistance, and alleviating the problem of thermal stress applied to the semiconductor laser chip due to hard solder. It can be done, and its practical effects are great.

It also has the advantage of good processing accuracy and is suitable for mass production.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an St submount in an embodiment of the present invention, FIG. 2 is a diagram showing a semiconductor laser device in which a semiconductor laser chip is bonded onto a heat sink using the above submount, and FIG. FIG. 4 is a diagram showing the submount thickness dependence of the resistance of the submount. 1...sb Doped n-type 5t (100) wafer, 2...St Wafer surface (side to which the laser chip is bonded), 3...500 thickness C
r, 4...500 thickness Ni-Or, 5
・-・・300OA thickness Ni, 6・・・・・3oo
O thickness Ag, T...1.8 μm thickness Sn
, 8...0.2 μm 1lAu, 9...
...Cu heat sink, 10...Au plating layer, 11...In solder layer, 12...
・Semiconductor laser chip. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 4 Scale fL1'' / 6. /near·! 7', / 413

Claims (2)

[Claims] (1) Semiconductor laser chip Si submount [1-
A semiconductor laser device characterized in that it is bonded to a Cu heat sink through a Cu heat sink. (2) St submount has a thickness of 1oo to 5ooμ
m. St submount made by vapor-depositing Cr/Ni/Agf on both sides of an St wafer doped with n-type SB and having a resistivity of 2×10-0-2Q or less, and vapor-depositing Sn and Auf on the side to which a semiconductor laser chip is bonded. A semiconductor laser device according to claim 1, characterized in that: