JPH08172238A - Manufacturing method of semiconductor laser device - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing a semiconductor laser element which is mounted on a sub-mount in a junction down without reliability deterioration due to electric short-circuit with high yield. CONSTITUTION: An n-type GaAs buffer layer 2, an n-type AlGaAs clad layer 3, an AlGaAs guide layer 4, an AlGaAs SCH layer 5, an InGaAs strained quantum wall active layer 6, an AlGaAs SCH layer 7, an AlGaAs SCH layer 8, an AlGaAs guide layer 8, a p-type AlGaAs clad layer 9, and a p<+> type GaAs contact layer are sequentially epitaxially grown on an n<+> type GaAs substrate 1, etched to reach the layer 9 by photolithography to form a ridge 11. Chipping cleavage grooves 12 are formed in a resonator direction at both sides, etched to the depth of about 3μm, an insulating film (SiO2 ) 13 is formed by sputtering on the entire surface, a p-type electrode 14 is provided thereon, and an n-type electrode is provided on the opposite surface of the substrate. An element is formed by cleaving along the grooves 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor laser device, and more particularly to a method for manufacturing a semiconductor laser device mounted by junction down.

[0002]

2. Description of the Related Art Heretofore, various semiconductor laser devices having a semiconductor laser element mounted on a submount by junction down have been proposed.

According to such a semiconductor laser device, the thermal resistance to heat generated from the active layer during laser operation can be reduced, so that the temperature rise of the active layer during high power operation can be suppressed. Since the temperature rise of the laser active layer induces dark line deterioration due to the growth of dislocations, suppressing the dark line is an important issue for the semiconductor laser device. Therefore, a stable and highly reliable semiconductor laser device can be realized by adopting a structure having a semiconductor laser element mounted on the submount in a junction-down manner.

By the way, in the conventional method of manufacturing a semiconductor laser device mounted on a submount by junction down, when the semiconductor laser device is separated from the laser array bar shape into individual laser chips, a semiconductor layer close to the junction is formed. The edge of the surface to be mounted was cleaved by applying a sharp cleavage blade at the tip. Next, in order to mount this semiconductor laser device on a submount, the semiconductor device is placed in a junction-down state on a preform material thin film formed on the submount in advance, and heat is applied to the preform material thin film. It was mounted.

[0005]

In the method of manufacturing the semiconductor laser device mounted on the above-mentioned conventional submount by junction down, in separating the semiconductor laser device from the laser array bar shape into individual laser chips,
The edge of the mounted surface near the junction was cleaved by applying a sharp cleavage blade at the tip. However, since the cutting edge of an actual cleavage blade has a finite thickness that is extremely large with respect to the crystal plane spacing to be cleaved, damage by the cleavage blade is caused near the edge of the mounted surface where the cleavage blade is applied and pressure is applied. It was a problem that the remaining part was generated. Also, in this state, when mounting by junction down on the submount, by placing the semiconductor laser element on the preform thin film formed on the submount in the junction down state and applying heat to the preform thin film, When mounted, it has a drawback that the preform material wraps around the cleavage damage portion and is electrically short-circuited. Therefore, the yield of semiconductor laser devices mounted by junction down is low,
Degradation of reliability due to electrical short circuit has been a problem.

An object of the present invention is to provide a method of manufacturing a semiconductor laser device mounted on a new submount by junction down without the above-mentioned drawbacks.

[0007]

According to the method of manufacturing a semiconductor laser device mounted on a submount by a junction down method according to the present invention, a preform material covered with an insulating film is wrapped around a mounted surface of the semiconductor laser device. The main feature is to have a step of forming a cleavage groove for chipping formed by etching to a depth that does not exist.

That is, the method for manufacturing a semiconductor laser device according to the first solution of the present invention is a semiconductor laser device mounted on a submount in a junction-down mode, in which a resonator is formed by etching the surface to be mounted of the semiconductor laser device by etching. The method is characterized by including a step of forming a groove parallel to the direction, a step of covering the etching groove with an insulating film, and a step of cleaving the etching groove portion.

A method of manufacturing a semiconductor laser device according to the second solution of the present invention is characterized in that the depth of the etching groove is 2 μm or more in the method of manufacturing according to the first solution.

[0010]

In the method of manufacturing a semiconductor laser device according to the present invention, for chipping to a depth such that the preform material covered with the insulating film does not go around the mounted surface of the semiconductor laser device mounted on the submount by junction down. A cleavage groove is formed by etching, and the cleavage groove portion is cleaved to separate each laser element. An ordinary laser uses an Au—Sn alloy with a thickness of about 3 μm as a preform material. Further, a gold electrode having a thickness of about 1 μm is formed on the mounted surface of the semiconductor laser device. Therefore, the chipping cleavage groove has a depth of 2 μm or more, so that even when this semiconductor laser device is mounted on the submount by junction down, the preform material wraps around the cleavage damage portion and is electrically short-circuited. It is possible to mount without doing. For this reason,
A semiconductor laser device mounted by junction down can be manufactured with high yield, and a highly reliable high output semiconductor laser device can be provided.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a process drawing showing a method for manufacturing a semiconductor laser device of an embodiment of the present invention, and (A) to (E) are cross-sectional views of a product being manufactured in each process.

In FIG. 1A, 1 is n ⁺ -GaAs
Substrate 2, n-GaAs buffer layer, 3 n-AlGa
As cladding layers, 4 and 8 are AlGaAs guide layers,
5 and 7 are AlGaAs SCH layers, 6 is InGaAs
Strained quantum well active layer, 9 p-AlGaAs cladding layer,
10 is a p ⁺ -GaAs contact layer, 11 is a ridge, 1
2 is a cleavage groove for chipping, 13 is an insulating film, 14 is a p-electrode, and 15 is an n-electrode.

In order to realize this structure, first, the epitaxial layers 2 to 10 are grown by an epitaxial crystal growth apparatus (MOCVD method: metal organic chemical vapor deposition apparatus or MBE method: molecular beam epitaxy method). In the MOCVD method, trimethylindium (TMI), triethylgallium (TEG), trimethylaluminum (TMA), arsine (AsH ₃ ) are used as raw materials for semiconductor thin film growth.
As an n-type dopant, selenium sulfide (H ₂ Se), p
Diethyl zinc (DEZn) was used as the type dopant. The epitaxial growth temperature is about 700 ° C., the growth pressure is about 0.1 atm, and the carrier gas is hydrogen. In the MBE method, metallic gallium (Ga), metallic indium (In), metallic aluminum (Al), and arsenic (As solid) were used as raw materials, silicon (Si) was used as an n-type dopant, and zinc (Zn) was used as a p-type dopant. . Epitaxial growth temperature is about 650 ° C, growth pressure is about 10 ^-5 Tor
r.

Next, as shown in FIG. 1B, the contact layer 10 and the cladding layer 9 are processed to have a width of 1.5 to 3
A ridge 11 of about μm is formed. For that purpose, patterning is performed by photolithography, and the contact layer 10 and the cladding layer 9 are etched by wet etching or dry etching using this as a mask. Since the semiconductor laser device that is the target of the manufacturing method of the present invention is mounted by junction down, it has a bank structure in which only the vicinity of the ridge portion is etched in order to maintain the flatness of the mounted surface. The etching depth is determined in consideration of the transverse mode, and the guide layer 8 may be etched in some cases. next,
As shown in FIG. 1C, a chipping cleavage groove 12 used when cutting a laser chip from the shape of a laser array bar is formed by etching. For that purpose, patterning is performed by photolithography, and using this pattern as a mask, wet etching or dry etching is performed to a depth of about 3 μm. After that, the mask is removed, and the insulating film 13 (SiO ₂
Etc.) is formed on the entire surface, and the insulating film such as SiO ₂ on the ridge is etched off (FIG. 1D), and then the p electrode 14 such as Cr / Au or Ti / Pt / Au or the n electrode such as AuGeNi is formed. Then, ohmic sintering is performed to form the electrode portion (FIG. 1 (E)), where the thickness of the p electrode is about 1 μm, after which cleavage is performed in the shape of a laser array bar. Al ₂ O ₃ on the light output end face in the state
An antireflection film formed by the end layer, and SiO ₂ / α on the other end surface
A high reflection film made of -Si is formed. Next, chipping is performed along the chipping cleavage groove 12 into the shape of the laser chip.

FIG. 2 is a sectional view showing a semiconductor laser device manufactured by mounting a semiconductor laser device obtained by the method of manufacturing a semiconductor laser device according to the embodiment of the present invention. In the figure, 16 is an Au / Sn preform material, and 17 is a diamond submount as a heat sink.

The mounting of the semiconductor laser device according to the process of FIG. 1 is carried out by mounting the manufactured semiconductor laser device on the diamond submount by junction down. For this purpose, a semiconductor laser element is placed on a diamond submount 17 on which an Au (80%) Sn (20%) thin film of about 3 μm is preliminarily formed on the mounted surface as the preform material 16 and heated to about 300 ° C. Stick to it.

[0018]

The semiconductor laser device obtained by the method for manufacturing a semiconductor laser device of the present invention and mounted on the submount by junction down is a preform in which the mounted surface of the semiconductor laser device is covered with an insulating film. By forming a cleavage groove for chipping formed by etching to a depth that does not wrap around the material, and cleaving this cleavage groove part and separating it into individual laser elements, this semiconductor laser element can be junction down on the submount. Even when mounted, the preform material can be mounted without wrapping around in the cleavage damage area and electrically short-circuiting, making it possible to fabricate semiconductor laser devices mounted with junction down with high yield, and It is possible to provide a high-power semiconductor laser device.

[Brief description of drawings]

1A to 1E are process diagrams showing a method for manufacturing a semiconductor laser device according to the present invention, and FIGS. 1A to 1E are cross-sectional views of a product in each process.

FIG. 2 is a cross-sectional view showing a semiconductor laser device mounted with a semiconductor laser element obtained by a method of manufacturing a semiconductor laser element according to an embodiment of the present invention.

[Explanation of symbols]

1 n ⁺ -GaAs substrate 2 n-GaAs buffer layer 3 n-AlGaAs clad layer 4 AlGaAs guide layer 5 AlGaAsSCH layer 6 InGaAs strained quantum well active layer 7 AlGaAsSCH layer 8 AlGaAs guide layer 9 p-AlGaAs clad layer 10 p ⁺ -GaAs Contact layer 11 Ridge 12 Cleaving groove for chipping 13 Insulating film 14 p electrode 15 n electrode 16 Au / Sn preform material 17 diamond submount (heat sink)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Eiichi Kuramochi 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (2)

[Claims] 1. In a semiconductor laser device mounted on a submount in a junction-down form, a step of forming a groove parallel to a cavity direction by etching on a mounted surface of the semiconductor laser device, and insulating the etching groove. A method of manufacturing a semiconductor laser device, comprising: a step of covering with a film; and a step of cleaving the etching groove portion. 2. The method of manufacturing a semiconductor laser device according to claim 1, wherein the depth of the etching groove is 2 μm or more.