JPH06169134A - Semiconductor laser and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a semiconductor laser provided with stripe grooves for current paths, wherein the semiconductor laser can be lessened in numbers of manufacturing processes and enhanced in yield dispensing a grooving process used for ascertaining a stripe groove pattern. CONSTITUTION:A current blocking layer 2 is grown on an inclined substrate 1, then stripe grooves 10 are provided, and furthermore a double hetero-structure composed of a P-clad layer 3, an active layer 4, an N-clad layer 5, and a cap layer 6 is made to grow, wherein a surface morphology which indicates the pattern of the stripe grooves 10 is observed on a growth surface, so that an N-side electrode 7 pattern is easily formed conforming to the surface morphology.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser having an inner stripe structure having a stripe groove for a current path and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a semiconductor laser having an inner stripe structure, it is necessary to form electrodes in accordance with the pattern of stripe grooves, and in the conventional manufacturing method, a so-called groove forming step is essential. 6 and 7
FIG. 6 is a perspective view showing a conventional method for manufacturing a semiconductor laser of this type including this groove forming step. Hereinafter, FIG. 6 and FIG.
A conventional manufacturing method will be described with reference to FIG.

First, after forming the current blocking layer 12 on the substrate 11, a plurality of stripe grooves 20 are formed at equal pitches in the mesa direction (FIG. 6A). Then, on the current blocking layer 12, p−
A double hetero structure is formed by laminating a clad layer 13, an active layer 14, an n-clad layer 15, and a cap layer 16 (FIG. 6).
(B)). Since the entire surface is covered with the double hetero structure and the pattern of the stripe groove 20 is unknown, the p-clad layer 13, active layer 14, n-
A so-called grooving step is carried out in which a part of the double hetero structure composed of the clad layer 15 and the cap layer 16 is removed to expose the stripe groove 20 in that part (FIG. 7C). Referring to the pattern of the exposed stripe groove 20, the stripe groove embedded on the remaining double hetero structure
A plurality of one electrodes 17 are patterned at an equal pitch according to 20, and the other electrode 18 is formed over the entire back surface of the substrate 11 (FIG. 7D).

[0004]

In the above-mentioned conventional manufacturing method, for example, a grooving step is indispensable, and this grooving step requires several kinds of etching solutions containing an ammonia-based etchant, and the total number of steps is In many cases, there is a problem that it takes a long time to manufacture. Also, since etching is performed after the growth of the double hetero structure, if there are pinholes on the surface of the double hetero structure or if the masking during etching is inadequate, the portion of the double hetero structure that should remain will also be exposed to the etching solution over a wide range. Being invaded,
There is also a problem that the characteristics of the manufactured semiconductor laser are poor and the yield is low.

The present invention has been made in view of such circumstances, and the number of steps can be reduced by eliminating the groove forming step, and the yield can be improved by eliminating the above-described etching. An object of the present invention is to provide a semiconductor laser and a manufacturing method thereof.

[0006]

A semiconductor laser according to the present invention is an inner stripe structure semiconductor laser having a stripe groove for a current passage on a substrate, wherein the substrate is an inclined substrate. .

A method of manufacturing a semiconductor laser according to the present invention is
In a method for manufacturing a semiconductor laser having an inner stripe structure having a stripe groove for a current path, a step of forming a current blocking layer on a tilted substrate, a step of forming the stripe groove in the current blocking layer, The method is characterized by including a step of forming a double hetero structure on the current blocking layer and a step of forming a pattern electrode in accordance with the surface morphology of the formed double hetero structure.

[0008]

In the present invention, a tilted substrate is used as the substrate.
When a double hetero structure is laminated by, for example, liquid phase growth after forming a stripe groove using an inclined substrate, surface morphology clearly showing the pattern (position) of the stripe groove appears on the surface. Then, a pattern electrode is formed according to the surface morphology. Since the pattern of the stripe groove can be recognized from the surface morphology without removing the double hetero structure by etching, the pattern electrode can be easily aligned with the stripe groove.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments.

FIG. 1 is a perspective view showing the structure of a semiconductor laser according to the present invention. In FIG. 1, 1 is Ga that is inclined from the (001) plane by more than 0 degree and 10 degrees or less.
It is an As tilted substrate. In this embodiment, from the (001) plane
It is a GaAs tilted substrate tilted by 0.5 degree. N-Ga in which stripe grooves 10 are provided at equal pitches on the inclined substrate 1
A current blocking layer 2 made of an As layer (film thickness: 1.2 μm) is laminated. On the current blocking layer 2, p-Al _0.4 Ga is formed.
_0.6- As layer (film thickness: 0.35 μm) p-cladding layer 3, undoped Al _0.06 Ga _0.94 As layer (film thickness: 0.05 μm) active layer 4, n-Al _0.4 Ga _0.6 As layer (film thickness: 2.5 μ)
m) n-clad layer 5, n-GaAs layer (film thickness: 3.5
μm) of the double heterostructure including the cap layer 6 is laminated. An n-side electrode 7, which is a pattern electrode, is formed on the cap layer 6 according to the pattern of the stripe groove 10, while a p-side electrode 8 is formed on the entire back surface of the tilted substrate 1. .

Next, a manufacturing method according to the present invention for manufacturing a semiconductor laser having a structure as shown in FIG. 1 will be described. 2 and 3 are perspective views showing steps of this manufacturing method.

First, a current blocking layer (n-GaAs layer) 2 is grown to a thickness of 1.2 μm on a GaAs inclined substrate 1 of 0.5 ° or more by a vapor phase growth method (FIG. 2A). Since the surface morphology showing the pattern of the stripe groove 10 can be seen in any direction, the GaAs tilted substrate 1 tilted in any direction from the (001) plane can be used. In the present embodiment, it is tilted in the <011> crystal axis direction. Next, a plurality of stripe grooves 10 (depth: 1.4 μm, width: 2.8 μm) are formed in the mesa direction at an equal pitch of 100 μm (FIG. 2B).

Then, a p-clad layer (p-Al _0.4 Ga _0.6 As) is formed on the current blocking layer 2 by a liquid phase growth method.
Layer) 3, active layer (u-Al _0.06 Ga _0.94 As layer) 4, n
- cladding layer (n-Al _0.4 Ga _0.6 As layer) 5, a cap layer (n-GaAs layer) 6, is grown by the film thickness, is stacked double heterostructure (Figure 3 (c)).
The growth temperature is 820 ℃ and the cooling rate is 0.5 ℃.
/ Min, and the growth time of each layer is 80 seconds, 1 second, 10
20 seconds and 900 seconds. Then, the pattern line A matching the stripe groove 10 can be seen in the surface morphology of the double hetero structure. FIG. 4 is a surface photograph after forming a stripe groove on an inclined substrate and growing a double hetero structure by a liquid phase growth method as in the present invention, which was affected by the stripe groove. The surface morphology is clearly observed, clearly indicating the position of the stripe groove. In FIG. 4, a whitish line-like portion is a portion affected by the stripe groove (corresponding to A in FIG. 3C). FIG. 5 is a photograph of the surface of a non-tilted ordinary substrate which has been subjected to the same treatment, and the surface morphology shows no influence of stripe grooves.

Pattern line A on the surface of the double hetero structure
To form a semiconductor laser as shown in FIG. 1 by patterning the n-side electrode 7 along the line and forming the other p-side electrode 8 over the entire rear surface of the tilted substrate 1 (FIG. 3D). ).

If the tilt angle of the tilted substrate used is large, or if the double hetero structure to be grown has a large film thickness, the stripe groove is affected not at a position directly above the stripe groove but at a position slightly displaced from the stripe groove. Although the surface morphology is observed, the regularity of the surface morphology due to the influence of the stripe groove is maintained in this case as well, so that the pattern electrode can be easily formed as in the above-described embodiments.

Although the semiconductor laser having a single stripe structure has been described in the above embodiments, the present invention can be applied to a semiconductor laser having an array structure, a broad area semiconductor laser, a multi-beam semiconductor laser and the like. .

[0017]

As described above in detail, in the present invention, since the pattern of the stripe groove can be easily confirmed by using the inclined substrate, the number of steps can be reduced by eliminating the groove forming step and the manufacturing time can be shortened. In addition, the present invention has excellent effects such that the yield is improved without being affected by the etching process in the groove forming process.

[Brief description of drawings]

FIG. 1 is a perspective view showing a structure of a semiconductor laser according to the present invention.

FIG. 2 is a perspective view showing steps of a method for manufacturing a semiconductor laser according to the present invention.

FIG. 3 is a perspective view showing a step of a method for manufacturing a semiconductor laser according to the present invention.

FIG. 4 is a surface photograph of a double hetero layer grown on a tilted substrate.

FIG. 5 is a surface photograph of a double hetero layer grown on a conventional non-tilted substrate.

FIG. 6 is a perspective view showing steps of a conventional method for manufacturing a semiconductor laser.

FIG. 7 is a perspective view showing steps of a conventional method for manufacturing a semiconductor laser.

[Explanation of symbols]

1 GaAs inclined substrate 2 current blocking layer (n-GaAs layer) 3 p-clad layer (p-Al _0.4 Ga _0.6 As layer) 4 active layer (u-Al _0.06 Ga _0.94 As layer) 5 n-clad layer (n- Al _0.4 Ga _0.6 As layer 6 Cap layer (n-GaAs layer) 7 n-side electrode 8 p-side electrode 10 Stripe groove A Pattern line that looks like surface morphology

Claims (2)

[Claims] 1. A semiconductor laser having an inner stripe structure having a stripe groove for a current path on a substrate, wherein the substrate is an inclined substrate. 2. A method of manufacturing a semiconductor laser having an inner stripe structure having a stripe groove for a current path, the method comprising forming a current blocking layer on a tilted substrate,
Forming the stripe groove in the current blocking layer, forming a double heterostructure on the current blocking layer,
And a step of forming a pattern electrode according to the surface morphology of the formed double hetero structure.