JPH03194989A - Manufacture of semiconductor laser - Google Patents

Abstract

PURPOSE:To allow a film thickness for obtaining a semiconductor laser to remain with excellent controllability by etching a wafer of a laser having no etching stop signal layer together with a dummy wafer in which an etching stop signal layer is mounted, and stopping etching by etching information of the dummy wafer having the signal layer. CONSTITUTION:A dummy wafer 21 with an etching stop signal layer 11 is mounted at a position (at the center) partly shown in a perspective state with a semiconductor wafer 20 having no etching stop signal layer 11 as a main body at an etching tool 23 dipped in an etchant tank 22. The etching is stopped when the interference color of the layer 11 of the wafer 21 is vanished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a self-oscillation type semiconductor laser with small variations in characteristics.

[Conventional technology]

FIG. 3 is a cross-sectional view of a conventional self-oscillation type semiconductor laser.

In the figure, (1) is n-type Atg, 5Gag, 5Aa
The lower quad layer (2) is p-type Ato, 15Ga (1,
85Aa active layer, (a) t'ip type At(1,50&
o, 5A8 top cladding, OQa with al = 0.35 μm is p-type At (1,5Gao, 5As
In the upper cladding layer, d3=1.0 μm. (4) is a striped mask. In addition, aυ is AtO of thickness d2 formed on the upper cladding thickness d1 to be left, 15
Etching stop signal layer of GaQ, [15A8, d2 = 0.05 μm.

The state in which a semiconductor laser having such a structure is being etched is shown in FIGS. 4 and 6. The upper cladding layer 4 is etched by the etching solution (7), and due to the optical path difference between the light reflected by the etching stop signal layer (6) and the upper cladding layer (2), the d4 film thickness is 0.4 μm or less. When this happens, interference stripes gradually appear.

This interference light gradually becomes stronger and disappears once the etching stop signal layer (6) is etched. Also, at this time, interference light (5) is generated by the surface of the upper cladding layer (3) and the active layer (2) that should be left, but the interference light (5) is generated between the etching stop signal layer (b) and the etching stop signal layer (b). Since the interference light (g) generated by the upper cladding layer (to) on the top of the etching is stronger, the disappearance of the etching stop signal layer (b) can be clearly determined, and if etching is stopped at this point, the upper cladding layer As a result, only a portion with a thickness of 9a and d1 remains due to crystal growth.

Thereafter, 2nd and 3rd growth is performed to form a semiconductor laser. In this configuration, since the etching stop signal layer (b) remains in the light emitting region, there is a drawback that the shape of the far-field pattern of the laser characteristics becomes abrupt.

[Problem to be solved by the invention]

Since the conventional method for manufacturing a semiconductor laser is configured and manufactured as described above, there has been a problem in that its characteristics become abrupt.

This invention was made to solve the above problems, and the film thickness d for obtaining a self-oscillation type semiconductor laser was
The aim is to maintain good controllability.

[Means to solve the problem]

The method for manufacturing a semiconductor laser according to the present invention does not provide an etching stop signal layer on the laser element itself, but etches a laser wafer without an etching stop signal layer together with a dummy wafer provided with an etching stop signal layer, and etches the etching stop signal layer. Etching is stopped based on etching information of a dummy wafer having a signal layer.

[Effect]

In the method for manufacturing a semiconductor laser according to the present invention, since an etching stop signal layer having a different refractive index is not formed within the emission region of the laser to be finally constructed, there is no problem with the characteristics of the laser device.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a perspective view showing a semiconductor laser etching method according to an embodiment of the present invention. In the figure, (7) is an etching solution, a dummy wafer is used to stop etching with an etching stop signal layer, and (1) is an etching stopper. A wafer without a signal layer, (A) is an etching liquid tank 0 Next, we will explain the previous work 0 An etching tool (2) immersed in an etching liquid tank (2)
2) includes an etching stop signal layer (
Mainly consists of a semiconductor wafer (E) without an etching stop signal layer (B), and a dummy wafer (B) with an etching stop signal layer (B) at t111 (the central part in the case shown), which is partially shown in perspective.
2) is attached, and the etching process is stopped when the interference color of the etching stop signal layer (b) of the dummy wafer disappears.

By doing this, a regular semiconductor chip having no etching stop signal layer can be etched well, and since it does not have an etching stop signal layer, no characteristic defects will occur.

FIG. 2 Fi shows a cross-sectional view of the semiconductor laser obtained by the etching process of FIG. 1. In the above embodiment, one dummy wafer (2) having an etching stop signal layer (b) was provided at the center of the etching tool 4, but it is not limited to the center and the interference color can be easily seen. It may be provided at any location. Also, dummy wafer (2)
is not limited to one, but may be more than one.

〔Effect of the invention〕

As described above, according to the present invention, the etching stop signal layer is provided only on the dummy wafer, and the etching of the entire dummy wafer is stopped depending on the etching state of the dummy wafer. This has the effect that the upper cladding thickness can be manufactured with good controllability.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a method of etching a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a semiconductor laser obtained by the method of manufacturing a semiconductor laser shown in FIG.
Figure 3 is a cross-sectional view of a conventional semiconductor laser, and Figures 4 and 5 are cross-sectional views showing a conventional etching method for a semiconductor laser. (1) is n Ato, 5Gao, 5Ae bottom cladding (2) #ip Ato, xsGJLo, 85A8 active layer, (3) is p At (1,5GJ'0.5Ae top cladding (4) is a striped mask, ( 7) is etching liquid, (b) is I) At0, 15GJLO, 85A
8-piece cutting stock V-signal layer, (Ll is p Ato
, 5Gag, BAs upper cladding layer, So is semiconductor wafer,
Ql) A dummy wafer with Fi etching stop signal fi/NI, (2) is an etching liquid tank, and (2) is an etching processing tool. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A GaAs semiconductor substrate having a first conductivity type, and an Al_ having a first conductivity type sequentially laminated on this semiconductor substrate.
xGa_1_-_xAs lower cladding layer, Al_yGa_
1_-_yAs active layer, film thickness d_ having second conductivity type
In the manufacturing method, the upper cladding layer has an Al_zGa_1_-_zAs upper cladding layer of 1, and the upper cladding layer is selectively etched leaving a stripe-shaped convex portion and leaving a film thickness of d_1. Al_z_'Ga_1_-_z of d_2 thickness on the remaining thickness d_1
Film with composition of __'As (etching stop signal layer)
At the same time, a dummy wafer with a film thickness of d_4 is etched.
A method for manufacturing a semiconductor laser, characterized in that etching is stopped when the interference color caused by the Al_z_'Ga_1_-_z_'As etching stop signal layer disappears.