JPS61115364A - Manufacture of semiconductor laser - Google Patents

Abstract

PURPOSE:To improve yield by cutting out a semiconductor laser without cleavage through etching. CONSTITUTION:A hydrochloric acid-resistant film 300 is formed onto the surface of a semiconductor crystal 200, which uses a (111) face as the surface and has double hetero-structure containing an active layer, in a striped manner in the direction parallel with a (011) face, and etched by hydrochloric acid gas, etc. A reflective surface 40 prepared at that time is made perpendicular, and forms a laser resonator. The reflective surface is flattened extremely by the characteristics of etching, and shapes an excellent surface as a laser reflective surface. The shape of the etching surface is not affected by the edge of a mask, and is determined only by a crystal face.

Description

[Detailed description of the invention] (Field of the invention) The present invention relates to a method for manufacturing a semiconductor laser.

(Prior art and its problems) Most conventional semiconductor lasers, except in the early stages of development,
), and currently they are manufactured on semiconductor substrates that have a (100) plane as a surface. The method of manufacturing a reflective surface by cleavage, which normally uses a cleavage plane of a crystal, has a very low yield (yield) for forming a laser resonator. Cleaving is a method of scratching and breaking the crystal, which does not always result in good cleavage planes and is not suitable for mass production. Semiconductor laser whose cavity surface is formed by etching (hereinafter referred to as etching laser)
Because the reflective surface is created by etching, it can be mass-produced and the resonator can be made short. However, conventionally, the reflective surface formed by etching has a curtain-like fine unevenness that reflects the edge condition of the IC etching mask, as shown in Fig. 4, and it does not provide a good reflective surface for a laser resonator. The increase and dispersion of the oscillation threshold current density causes problems with etching lasers, and the yield is actually very poor.

(Object of the present invention) An object of the present invention is to eliminate the above-mentioned problems and provide a method for manufacturing a semiconductor laser that is excellent in mass production and has a high yield. (Configuration of the present invention) Manufacturing of the present invention The method includes the step of forming a semiconductor laminated structure having a double heterostructure including an active layer on a semiconductor substrate with a (111) plane as the surface, and a step of forming a reflective surface constituting a laser resonator on the semiconductor layer with hydrochloric acid resistance. An etching pattern consisting of a film is formed and the film is exposed to an etching gas atmosphere to show the hydrochloric acid resistance. FIG. 1 is a perspective view of a semiconductor laser manufactured by the manufacturing method of the present invention. An active layer 10 and a cladding layer 2 are formed on a semiconductor substrate 100 having a (111) plane as a surface.
0 and a cladding layer 30. The etched reflective surface 40 forming the laser cavity is (
01i > plane or an equivalent crystal plane. This etching surface uses an etching pattern made of a hydrochloric acid-resistant film, and is etched using hydrochloric acid gas.

It is formed by exposing to an atmosphere of chloride gas of HBr, C1*-Brl-V group element, etc., and etching the crystals other than the area covered with the hydrochloric acid-resistant film. The crystal shape at that time will be explained in detail in FIG.

FIG. 2(a) shows a crystal whose surface is the (111) plane and its cleavage plane. As shown in (b), a hydrochloric acid-resistant coating 300 is formed in stripes in a direction parallel to the (oxi) plane on the surface of a semiconductor crystal 200 having an IC (111) plane as the surface and a double heterostructure including an active layer. Etching with gas etc. At that time, the cross section of A-A' is the etched reflective surface 4 made by etching, as shown in (c).
0 is vertical and forms a laser resonator. As shown in FIG. 3, the reflective surface is determined by engineering. still,
Etching gases include hydrochloric acid gas, HBr, A4
Chlorides of group V elements, etc. are effective.

Al7. JGaoyAs cladding layer 20. Thickness 1.2
A semiconductor crystal having a double heterostructure with a diameter of .mu.m was formed.

A stripe mask was formed thereon using StO.

Thereafter, the material was introduced into an etching apparatus, and the temperature was raised to 900.degree. C. while flowing AsHl, and in this state, hydrochloric acid gas was introduced to perform etching. The gas flow rate at that time is 1.5 sec
mA sH618sec and H as carrier gas
The total flow rate was set to LSlm. The etching atmosphere is 7 QTorr. The hydrochloric acid gas was stopped, and the temperature was lowered while AsH was flowing, and the AsH was stopped to complete the etching.

The etching depth was 20 μm. Thereafter, an electrode (indicated by ! in FIG. 1) was formed by vapor deposition using a metal mask, and it was divided into individual chips to form a laser.

(Effects of the invention) Since the laser resonator is formed by etching,
No cleavage is required, and the etching surface can be inspected using a scanning electron microscope in the same way as a normal IC. When observed under magnification, it is indistinguishable from the surface of a commercially available crystal substrate normally used for crystal growth. Since gas phase etching is used, a large number of laser reflecting surfaces can be fabricated at one time, resulting in excellent mass productivity.

As described above, the present invention is a method for manufacturing a semiconductor laser that is excellent in mass productivity and has a high yield.

In the present invention, the double heterostructure may include a buried structure or the like. In addition, the example is AlGaAs/GaA
Although this is an example of s mixed crystal, other mixed crystal systems may be used.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of a semiconductor laser manufactured by the method of the present invention, FIGS. 2(a) to (c) are diagrams showing etched shapes, and FIG. FIG. 4 is a diagram showing an example of the shape of a conventional etching reflective surface. In the figure, 100 is a semiconductor substrate, 10 is an active layer, 20, 3
0 is a cladding layer, 200 is a semiconductor crystal having a double heterostructure, and 300 is a hydrochloric acid-resistant coating. Director of Industrial Technology Agency

Claims (1)

[Claims] forming a stacked structure having a double heterostructure including an active layer on a semiconductor substrate having a (111) plane as a surface;
forming an etching pattern made of a hydrochloric acid-resistant film on the semiconductor laminated structure and exposing it to an etching gas atmosphere;
A method of manufacturing a semiconductor laser, comprising at least the step of forming a reflective surface constituting a laser resonator by performing vapor phase etching on the crystal other than the region covered with the hydrochloric acid-resistant film.