JPH0582901A - Fabrication of semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain a method for easily fabricating a semiconductor laser device having window regions of same size on the opposite end faces. CONSTITUTION:A lower clad layer 2, an MQS active layer 3, an upper clad layer 4 and a contact layer 5 are formed in order on a semiconductor substrate 1 and a V-groove 6 is made from the contact layer 2 upto the upper clad layer 4. Zn is then diffused over the entire surface from the contact layer side toward the contact layer to disorder the MQW structure only in the vicinity of the V-groove 6. It is then cleaved with the end of the V-groove 6 as a positional reference thus obtaining a semiconductor laser device having window regions on the opposite end faces.

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 used for information equipment such as an optical disk device, and more particularly to improvement of an end face window forming technique.

[0002]

2. Description of the Related Art FIGS. 3A to 3C are cross-sectional views showing a method of forming an end face window region of a conventional semiconductor laser device shown in ELECTRONICS LETTERS 1984.
GaAs substrate, 2 is an n-AlGaAs cladding layer, 3 is an active layer having a quantum well structure (hereinafter referred to as MQW active layer),
4 is a p-AlGaAs cladding layer, 5 is a p-GaAs cap layer, 10 is a SiN mask, 11 is a Zn-diffusion region, 12 is a region in which a quantum well structure (hereinafter, referred to as MQW structure) is disordered, and 13 is The arrow indicates the Zn diffusion step, 21 is the p electrode, 22 is the n electrode, and 23 is the arrow indicating the cleavage direction.

The process of forming the end face window region of the semiconductor laser device will be described below. First, as shown in FIG. 3 (a),
The n-Al is formed on the n-GaAs substrate 1 by the MBE method or the like.
GaAs cladding layer 2, GaAs well layer and AlGaA
MQW active layer 3 composed of s barrier layer 3, p-AlGaA
The s-clad layer 4 and the p-GaAs cap layer 5 are sequentially crystal-grown.

Next, Si is formed on the p-GaAs cap layer 5.
The N film 10 is vapor-deposited, and the photolithography technique is used.
After forming a 30 μm stripe-shaped window, the n-GaAs substrate 1 having each of the above crystal layers is inserted together with ZnAs in a closed quartz tube, and heat-treated at 665 ° C. for 90 minutes, as shown in FIG. 3 (b). Zn is p-GaAs
The Zn-diffused region 11 is formed by selectively diffusing from the cap layer 5 side to only the region without the SiN film 10 (arrow 13). Then, at this time, the MQW active layer 3 in which Zn is diffused
In the disordered region 1 where the GaAs well layer and the AlGaAs barrier layer are disordered, the MQW structure is disordered compared to the original MQW active layer 3, and the band gap is wide.
2 is formed.

Next, AuG is formed on the lower surface of the n-GaAs substrate 1.
n-electrode 22 made of eNi, p-GaAs cap layer 5
After the p-electrodes 21 made of CrAu are formed on the upper surfaces of the respective layers, by cleaving in the direction of arrow 13 in the central portion of the Zn diffusion region 11, as shown in FIG. A window area is formed in the area.

[0006]

Since the step of forming the end face window region of the conventional semiconductor laser device has been performed as described above, it is necessary to form a mask (SiN film 10) for selective diffusion. , The number of steps is increased, and the cleavage must be performed at the center of the window portion with high precision at the time of cleavage, which sometimes results in forming a device in which the window region size is different between the front end face and the rear end face of the laser device. There are problems that the characteristics of the semiconductor laser device are not stable and the yield is reduced.

The present invention has been made to solve the above-mentioned problems, and it is possible to easily and accurately form window regions of the same size on the front end face and the rear end face of a laser device without using a selective diffusion mask. An object of the present invention is to obtain a method for manufacturing a semiconductor laser device in which end face window regions are formed on both end faces that can be formed.

[0008]

A method of manufacturing a semiconductor laser device according to the present invention is a multilayer semiconductor crystal layer including an active layer having a quantum well structure on a semiconductor substrate and two upper and lower clad layers sandwiching the active layer. Then, a V-shaped groove is formed from the semiconductor substrate side or the uppermost layer side of the multi-layer semiconductor crystal layer toward the inside of the multi-layer semiconductor crystal layer to disorder the quantum well structure in a subsequent step (displacement). The area to be ordered) and the cleavage position are determined in advance.

[0009]

In the method of manufacturing the semiconductor laser device according to the present invention, the V formed from the semiconductor substrate side or the uppermost surface of the multilayer semiconductor crystal layer toward the inside of the multilayer semiconductor crystal layer.
Since the V-shaped groove serves as a position reference between the disordered region of the quantum well layer and the region where the semiconductor substrate and the multilayer semiconductor crystal layer are cleaved, a disordered region of the same size is formed on each end face obtained after the cleavage. To be done.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view for each step showing a step of forming an end face window region in a manufacturing process of a semiconductor laser device according to an embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 6 is a V-shaped groove for cleavage, 13
Is an arrow indicating the diffusion step, and 23 is an arrow indicating the cleavage direction.

The process of forming the end face window region will be described below with reference to FIG. First, MOCVD is performed on the n-GaAs substrate 1.
N-AlGaAs cladding layer 2, GaAs
After the MQW active layer 3, the p-AlGaAs clad layer 4, and the p-GaAs contact layer 5 consisting of the well layer and the AlGaAs barrier layer are successively crystal-grown, as shown in FIG. 1 (a) by photolithography and wet etching. , V-shaped groove 6 for cleavage is formed. Here, the V-shaped groove 6 is formed such that the tip of the groove is in the p-AlGaAs cladding layer 4 and does not reach the MQW active layer 3. Next, a ZnO / SiO ₂ film (not shown) is deposited on the entire surface of the wafer including the p-GaAs contact layer 5 and the p-AlGaAs cladding layer 4 in the V-shaped groove 6 by using a sputtering apparatus, and then these layers are deposited on the upper surface. Formed n-GaAs substrate 1
1 is placed in an annealing furnace and heat-treated, Zn diffuses (arrow 13) as shown in FIG. 1 (b), and a Zn diffusion region 11 is formed. At this time, since the diffusion depth of the diffusion is uniform over the entire wafer, Zn is formed in the MQW active layer 3 only near the V-shaped groove 6.
In the MQW active layer 3 in which the diffusion region is formed and Zn is diffused, the GaAs well layer and the AlGaAs barrier layer are disordered, and the disorder region 12 having a wider band gap than the original MQW active layer 3 is formed.

Next, Au is formed on the lower surface of the n-GaAs substrate 1.
After forming the n-electrode 22 made of GeNi and the p-electrode 21 made of CrAu on the upper surface of the p-GaAs cap layer 5, respectively, cleavage is performed in the cleavage direction (direction of arrow 23) with reference to the tip of the V-shaped groove 6. By doing so, it is possible to form window regions of uniform size on both end faces of the laser. In such an end face window region forming step of this embodiment, p-GaA is used.
Since the Zn is diffused after the V-shaped groove 6 is formed from the s contact layer 5 toward the p-AlGaAs cladding layer 4, a part of the MQW active layer 3 (of the V-shaped groove 6 is formed without using a diffusion mask). Since the lower MQW active layer 3) can be modified into a disorder region 12 having a wide band gap, the crystal layer in which this disorder region 12 is formed can be cleaved with the tip of the V-shaped groove 6 as a reference. It is possible to easily form window regions of the same size on the front end face and the rear end face of the laser device.

FIG. 2 is a sectional view showing the steps of forming an end face window region in a manufacturing process of a semiconductor laser device according to a second embodiment of the present invention. In the figure, the same reference numerals as in FIG. 1 are the same or equivalent. 7 indicates p-GaAs.
A substrate, 8 is an n-GaAs contact layer. And
In the process of this embodiment, p-AlGa is formed on the p-GaAs substrate 7.
From the substrate 7 side to p-, a multi-layer crystal layer in which an MQW active layer 3 composed of an As clad layer 4, a GaAs well layer and an AlGaAs barrier layer 3, an n-AlGaAs clad layer 2 and an n-GaAs contact layer 8 are sequentially formed is provided. AlGaAs
A V-shaped groove 6 is formed toward the clad layer 4, and Zn is diffused (arrow 13) from the substrate 7 side in the same manner as in the above embodiment.
A part of the MQW active layer 3 is modified into a disorder region 12, and further, the cleavage direction 23 is based on the tip of the V-shaped groove 6.
It was cleaved along.

In the step of forming the end face window region of this embodiment, a mask for diffusing Zn is not required as in the above embodiment, and the cleavage is performed with the tip of the V-shaped groove 6 as a reference. Since it can be performed, it is possible to form the window regions of the same size on the front end face and the rear end face of the laser device which can be easily obtained as in the above embodiment.

In the above embodiment, the MQW near the V-shaped groove is used.
As a method of disordering the active layer 3, ZnO / SiO ₂
Although solid phase diffusion using a film is used, a disordered region may be formed by vapor phase diffusion in which a diffusion source such as ZnAs and a wafer are placed in a closed quartz tube and heat treatment is performed, or ion implantation and heat treatment are performed. Also in, it is possible to obtain the same effect as in the above embodiment.

[0016]

As described above, according to the present invention, a V-shaped groove is formed at a desired position on the uppermost layer of the semiconductor substrate or the multilayer semiconductor crystal layer, and the V-shaped groove is used as a position reference for activation. Since the layers are disordered and the substrate and the multilayer semiconductor crystal layer are cleaved, only the MQW active layer in a desired region can be disordered without using a mask, and the cleavage can be performed with high accuracy without requiring alignment. And as a result,
There is an effect that a semiconductor laser device having window regions of the same size formed on both end faces can be obtained with a high yield by a simple process.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of steps showing a manufacturing process of a semiconductor laser device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of process steps showing a manufacturing process of a semiconductor laser device according to another embodiment of the present invention.

3A to 3C are cross-sectional views for each manufacturing step showing a conventional manufacturing process of a semiconductor laser device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 n-GaAs substrate 2 n-AlGaAs clad layer 3 MQW active layer 4 p-AlGaAs clad layer 5 p-GaAs contact layer 6 Cleaved V-shaped groove 10 SiN mask 11 Diffusion region 12 MQW structure disordered region 13 Arrows showing diffusion process 21 p electrode 22 n electrode 23 Arrow showing cleavage direction

Claims (1)

[Claims] 1. A multilayer semiconductor crystal layer including an active layer having a quantum well structure and two upper and lower clad layers sandwiching the active layer is provided on a semiconductor substrate, and end faces are provided on both end faces of the multilayer semiconductor crystal layer. In a method of manufacturing a semiconductor laser having a window region formed, a step of sequentially performing crystal growth on a semiconductor substrate to form the multilayer semiconductor crystal layer, and a step of forming an active layer having a quantum well structure in the multilayer semiconductor crystal layer. Forming a V-shaped groove from the semiconductor substrate side or the uppermost layer side of the multilayer semiconductor crystal layer toward the clad layer so that the tip of the groove does not reach; A step of diffusing or injecting impurities into the entire surface of the multilayer semiconductor crystal layer from the upper layer side to disorder the quantum well structure of the active layer located in the vicinity of the V-shaped groove; A step of forming an electrode on the surface and the uppermost layer of the multilayer semiconductor crystal layer; and a step of cleaving the semiconductor substrate and the multilayer semiconductor crystal layer with the tip of the V-shaped groove as a reference. Laser device manufacturing method.