JP3377553B2 - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To prevent die bonded solder from coming into contact with a junction exposed to a chip side especially when assembling J/D required for low temperature characteristics. CONSTITUTION:Barrier layers 7a and 7b are formed on both surfaces of a sub-mount board 10. Furthermore, an AuSn eutectic solder layer 8 is partially formed on the barrier layer 7b where an AuSn eutectic solder layer 9 is installed to the whole surface of the barrier layer 7b. This construction makes it possible to inhibit the amount of solder which swells out to a chip side to a satisfactory extent, thereby providing a high reliability laser element which reduces an initial failure attributable to soldering short to a junction and which is virtually immune to the effect of solder in an environmental test.

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a semiconductor laser device.
Relates, in particular, those which relate to those with sub-mount for an optical semiconductor used to implement the optical semiconductor element. FIG. 3 is a cross-sectional view of a die-bonded submount of a conventional semiconductor laser device. In the figure, 1
Is a laser chip, 2 is a surface metallization provided on the bonding surface of the laser chip 1, 3 is a light emitting point of the laser chip 1 at which laser light is emitted, 4 is a submount for mounting the laser chip 1, and 5 is the above. A metal block 6 on which the submount 4 is mounted is a solder for bonding the laser chip 1 to the submount 4. Next, an assembling method will be described. In FIG. 3, a laser chip 1 has a solder metallization for bonding (not shown) on a surface metallization 2 of the laser chip. In assembling a laser, generally, a metal block 5 having good heat radiation is provided via a submount 4. Chip 1 using solder 6
Are adhered. Further, when used in an ODD (magneto-optical disk driver) or a printer, a J / D (junction down) assembly is required in which the light emitting point 3 is assembled close to the submount 4 in order to obtain low thermal resistance and low thermal characteristics. It is essential. In this case, the solder 6 in the die bond melts between the chip 1 and the submount 4 and spreads to the peripheral portion of the chip 1 to be finally fixed. μm
The fixed solder 6 may come into contact with the PN junction exposed on the side of the chip 1. [0004] Since the conventional semiconductor laser device having the submount for an optical semiconductor element is configured as described above, the solder that has protruded to the surface of the submount during die bonding is removed. Contact with the junction exposed on the chip side near the light emitting point, causing an initial short-circuit failure and a reduction in yield, and even if the initial failure can be avoided, the micro-discharge phenomenon occurs during user use. Therefore, there is a problem that a short circuit may occur in which the solder intermittently contacts the junction. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and prevents a solder at the time of die bonding from coming into contact with a junction exposed on the chip side to cause a short-circuit failure, thereby reducing the yield. is high and the characteristics vary in environmental resistance test is small, and an object that you obtain a highly reliable semiconductor laser device. [0006] A semiconductor laser device according to the present invention includes a submount provided on a heat-dissipating metal block via a solder layer, and a submount provided on the submount. In order from the submount side, a first Ti layer,
A barrier metal layer formed of a second layer of Ni or Pt and a third layer of Au, and a main surface disposed on the barrier metal layer and opposed to each other across the active layer; One main surface of the main surface close to the active layer is interposed between the semiconductor laser chip facing the barrier metal layer and the semiconductor laser chip and the barrier metal layer, and is arranged in a width corresponding to the semiconductor laser chip. The thickness of the Sn laser chip is reduced smoothly from the side of the semiconductor laser chip toward the barrier metal layer.
Deposition or spa using a material with a degree of 99.9999% or more
And a eutectic solder layer made of AuSn formed by a cutter . In the present invention, since the eutectic solder formed on the side of the submount that contacts the laser chip is limited to a size corresponding to the chip size, the solder at the time of die bonding is formed. , Which protrudes greatly to the chip side and comes into contact with the junction part, and even if it does, it is formed of eutectic solder, so it fits well with the barrier layer and forms a solder fillet with good surface condition And almost no contact with the junction. [0008] [Embodiment 1]. Hereinafter, a submount for an optical semiconductor element of a semiconductor laser device according to an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 40 denotes a submount made of silicon, silicon carbide, or aluminum nitride, and a submount base 1 constituting the submount 40.
The barrier metal layers 7a and 7b each including a first layer Ti layer 71, a second layer Ni layer or a Pt layer 72, and a third layer Au layer 73 are formed on both surfaces of the first barrier metal layer 7, respectively.
An AuSn solder layer (Sn wt% = 20 to 40%) 8 having a size corresponding to the size of the laser chip 1 is provided on the surface of a, and an AuSn solder layer 9 is formed on the surface of the other barrier metal 7b. FIG. 2 is a cross-sectional view showing a state where a laser chip is die-bonded using the submount 40. The same reference numerals as those in FIG. 3 denote the same or corresponding parts. Next, the operation and effect will be described. An AuSn solder layer 8 corresponding to the size of the laser chip 1 is formed on the surface of the submount substrate 10 on which the barrier metal 7a is formed by vapor deposition or sputtering.
AuS is entirely formed on the surface on which the barrier metal 7b is formed.
The n solder layer 9 is formed by vapor deposition or sputtering.
In this case, the purity of Sn is 6 as an evaporation source or a sputtering source.
By using more than N (99.9999%),
In solder melting at the time of die bonding, the underlying barrier layer 7a
And the AuSn eutectic solder layer having a smooth surface shape is formed. As shown in FIG. 2, when the J / D (junction down) assembly is performed using such a submount 40, the solder 8 protruding to the side of the laser chip 1 is sufficiently suppressed. There is almost no solder short to the junction. Further, even in an environmental test such as a heat cycle or high-temperature storage, a highly reliable laser device with little fluctuation in laser characteristics can be obtained. As described above, according to the semiconductor laser device of the present invention, the barrier layers are provided on both surfaces of the submount substrate, and the size of the laser chip is further provided on the main surface side of the substrate. Considerable size, the purity of Sn is 99.999.
Formed by vapor deposition or sputtering using a material of 9% or more
Since the eutectic solder layer made of AuSn is provided and the eutectic solder layer is formed on the entire back surface of the substrate, the amount of solder that protrudes to the chip side during die bonding can be sufficiently suppressed, and the exposure to the chip side can be achieved. In addition to being able to improve the yield by sufficiently suppressing the short-circuit of the solder to the junction, the solder is hardly affected by environmental tests such as heat cycle and high-temperature storage, and has high reliability with little characteristic fluctuation. There is an effect that a semiconductor laser device can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a submount for an optical semiconductor element of a semiconductor laser device according to an embodiment of the present invention. FIG. 2 is an apparatus cross-sectional view when a semiconductor laser element is mounted using the submount. FIG. 3 is an apparatus cross-sectional view showing a state when a conventional semiconductor laser device is die-bonded. [Description of Signs] 1 Laser chip 2 Surface metallization 3 Light emitting point 4 Submount 5 Metal block 7a Barrier metal 7b Barrier metal 8 Partial AuSn solder layer 9 Full AuSn solder layer 10 Submount base

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Claims (1)

(57) [Claims] [Claim 1] A submount disposed on a heat-dissipating metal block via a solder layer, and a submount disposed on the submount and arranged in order from the submount side. One Ti layer, second Ni layer or Pt
A barrier metal layer formed of an Au layer as a third layer, and a main surface disposed on the barrier metal layer and facing each other with the active layer interposed therebetween. A semiconductor laser chip having one main surface facing the barrier metal layer, a semiconductor laser chip interposed between the semiconductor laser chip and the barrier metal layer, arranged in a width corresponding to the semiconductor laser chip, and The film thickness decreased smoothly from the side toward the barrier metal layer, Sn
Using a material having a purity of 99.9999% or more
And a eutectic solder layer made of AuSn formed by sputtering .