JPS63107183A - Semiconductor laser device and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable a laser array to be manufactured with good reproducibility by providing dummy channels which do not become a semiconductor laser beam emitting section on both sides of the channels, thereby making uniform the thickness of each resonator and the characteristics of the laser beam emitted from each resonator. CONSTITUTION:On the principal surface of the substrate 2 of a semiconductor laser device 12, three channels 1 shaped in a reverse trapezoid is provided in parallel with each other, on both sides of which dummy channels 11 are provided. In the manufacture of the semiconductor laser device 12, a step easily develops in the parts of a lowermost clad 3 corresponding to the corners of each groove, but, since the distance between the respective grooves is several mum to several tens of mum, namely close to each other, a step develops only in the parts corresponding to the outer corners of dummy channels 8 and the surface of the clad layer 3 becomes a planar surface in the other channels 1 parts. As a result, the thickness of an active layer 4 corresponding to the three channels 1 parts dedicated to a laser array does not vary, becoming a homogeneous and uniform thickness. Therefore, the light emitting characteristics in each resonator 7 becomes uniform and stable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor laser device, for example, a multichannel semiconductor laser device having a plurality of resonators that emit laser light, and a method for manufacturing the same.

[Conventional technology]

Semiconductor lasers are widely used as light sources for information processing devices such as digital audio discs, video discs, optical disc files, and laser beam printers, and as light sources for optical communications.

Due to the demand for high-power semiconductor lasers, GaAlAs-based semiconductor laser devices in the 0 and 8 μm bands are limited by facet deterioration and operating life, so so-called multi-channel lasers (laser array)
is being developed.

Generally, when high power laser light is required, i.e.
When the near-field image is not a concern, laser arrays are used, which include multiple resonators on a single laser chip.

For laser arrays, see Nikkei Electronics 4, November 19, 1984, published by Nikkei McGraw-Hill.
It is written in the day number, P187 to P2O6. This document shows an example in which 5 to 40 resonators are arranged in parallel to increase the output of a semiconductor laser. Furthermore, this document describes that a channel is provided on the main surface of the substrate, and a cladding layer, an active layer, and a cladding layer are formed on the channel.

A structure in which multiple camp layers are epitaxially grown is shown.

[Problem that the invention seeks to solve]

Generally, when high-output laser light is required, a laser array as described above is used.

By the way, according to the analysis of the present inventor, as shown in FIG. 6, when a plurality of channels 1 are arranged parallel to the main surface of the substrate 2, a cladding layer 3. Active layer 4. Crat layer 5. In the multilayer growth layer consisting of the cap layer 6, a step is formed where the lowermost cladding layer 3 corresponds to the shoulder portion of the channel 1, and the thickness of the active layer 4 formed thereon is uneven (partially 9 or, as shown in FIG. It has been found that the characteristics of the laser beam emitted from No. 7 vary. It has also been found that when there are a large number of channels 1, the thickness of the active layer 4 is not non-uniform and the characteristics are stable, except for the channels on both sides. In addition, 8 shown in FIG. 6 is a diffusion layer for current confinement and ohmic contact, 9 is an anode electrode, and 10 is a cathode electrode.

An object of the present invention is to provide a semiconductor laser device having a plurality of resonators, in which the characteristics of each part of the resonator are uniform, and a method for manufacturing the same.

The above and other objects and novel features of the present invention include:
It will become clear from the description in this specification and the accompanying drawings.

[Means for solving problems]

A brief overview of typical inventions disclosed in this application is as follows.

That is, in the semiconductor laser device of the present invention, when a plurality of dummy channels forming a laser array are provided on the main surface of a GaAs substrate, one dummy channel is provided on each side of the channel group, and then a cladding layer is formed. , an active layer, a cladding layer, a cap layer, and a multilayer growth layer are formed by epitaxial growth layers. As a result, in the bottom cladding layer of the multilayer growth layer, a step is created on the dummy channels located at both ends of the channel group, so the cladding layer formed above may become partially thin. However, since the thickness of the cladding layer on the channel provided to the laser array is uniform, the thickness of the active layer formed thereon is uniform, and the laser light emission characteristics are uniform and stable. do.

[Effect]

According to the above means, the semiconductor laser device of the present invention is
Since dummy channels are provided on both sides of the channel group used for the laser array, when a multilayer growth layer is formed on the channel by epitaxial growth, even if the thickness of the bottom layer varies and a step occurs, this can be avoided. Since the stepped portion appears only on the dummy channel and does not appear on the channel provided to the laser array, the thickness of each resonator becomes uniform, and the characteristics of the laser light emitted from each resonator become uniform.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a semiconductor laser device according to an embodiment of the present invention, and FIGS. 2 to 5 are views showing a method of manufacturing the semiconductor laser device, and FIG. 2 shows a wafer having a channel. 3 is a cross-sectional view of a wafer with a multilayer growth layer formed on its main surface by epitaxial growth, FIG. 4 is a cross-sectional view of a wafer with a diffusion layer provided, and FIG. 5 is a cross-sectional view of a wafer with an electrode provided. FIG.

In this embodiment, an example in which a laser array is constructed using C8P type semiconductor lasers will be described.

The semiconductor laser device according to this embodiment has a structure as shown in FIG. That is, the semiconductor laser element (laser chip) 12 includes a cladding layer 3 made of n-type GaAfLAS formed on a substrate 2 made of n-type GaAs, and a cladding layer 3 made of GaAfLAS formed on the cladding layer 3.
an active layer 4 made of S, a cladding layer 5 made of p-type GaA and IAs formed on this active layer 4, and a camp layer 6 made of p-type GaAS formed on this cladding layer 5.
A multilayer growth layer consisting of and is provided. Further, on the main surface of the substrate 2, there are three parallel inverted trapezoidal channels (
Groove) 1 is provided. Furthermore, dummy channels 11 are provided as dummies on both sides of these channel groups. This dummy channel 11 has a cross-sectional shape similar to that of the channel 1 described above.

Further, the cap layer 6 is provided with p-type diffusion layers 8 for current confinement and ohmic contact, which are shown as dots that reach halfway into the cladding layer 5. These diffusions N8 are provided corresponding to the three channels 1 excluding the dummy channel 11.

On the other hand, an anode electrode 9 is provided on the top surface of the substrate 2, and a cathode electrode 10 is provided on the back surface.

Therefore, when a desired voltage is applied to the anode electrode 9 and the cathode electrode 10, the active layer 4 located above the three channels 1 forms a resonator 7 as shown by cross hunting. , laser light is emitted from both ends of these resonators 7.

In manufacturing such a semiconductor laser element (laser chip) 12, a cladding layer 3 is formed on the main surface of the substrate 2. Active layer 4. Cladding layer 5. A multilayer growth layer of camp layer 6 is formed. At this time, since there is a channel on the main surface of the substrate 2, generally, at least the bottom layer cladding N3 tends to have a step difference at a location corresponding to the shoulder portion of each groove, but in the case of this embodiment, Since the intervals between the grooves are close to each other, ranging from several μm to several tens of μm, a step appears only in the channels on both sides, that is, in the portion corresponding to the outer shoulder of the dummy channel 8, and the difference in level in the other channels 1. In some parts, the surface of the cladding layer 30 becomes a flat surface.

As a result, the thickness of the active layer 4 corresponding to the three channel 1 portions provided to the laser array becomes homogeneous and uniform without variation, and the light emission characteristics in each resonator 7 become uniform and stable. For reference, to introduce the thickness of the cladding layer 3, when the thickness a of the cladding layer 3 on the outside of the dummy channels 11 on both sides is about 0.4 μm to 0.5 μm, the thickness of the cladding layer 3 on the channel 1 is b is 0.2μm
It becomes about 0.3 μm.

Next, a method for manufacturing the semiconductor laser device will be described with reference to FIGS. 2 to 5.

When manufacturing the semiconductor laser element (laser chip) 12, first, as shown in FIG. 2, a compound semiconductor thin plate (wafer) 13 made of GaA,s is prepared. This wafer 13 consists of a rectangular n-type GaAs substrate (substrate) 2, and already has three channels (?a
) 1, and one dummy channel 11 provided on each side of these channels 1.

The channel 1 and the dummy channel 11 are identical in cross section and have an inverted trapezoidal shape.

Next, as shown in FIG.
On the main surface of No. 3, n-type G was formed by liquid phase epitaxial method.
Cladding layer made of aAlAs 3° Active layer made of GaAlAs 4. Cladding layer made of p-type GaAlAs5.
A cap layer 6 of p-type GaAs is sequentially formed to form a multilayer growth layer.

At this time, a step appears only in the portions corresponding to the outer shoulders of the dummy channels 11 on both sides, but in other portions of the channel 1, the surface of the cladding layer 3 becomes a flat surface. As a result, the active layer 4 formed on the cladding layer 3 also has a portion corresponding to the stepped portion of the cladding layer 3.
The thickness of the cladding layer 3 changes to produce a thin portion 15, but since the surface of the cladding layer 3 extending in the area corresponding to the portion of the three channels 1 provided to the laser array is flat, The thickness of the active layer 4 provided is homogeneous and uniform. Therefore, the light emission characteristics in the resonator 7 (see FIG. 4) shown by the cross-hunting of the active layer 4 corresponding to each channel 1 are constant.

The thickness of each layer constituting the multilayer growth layer is, for example, n
The p-type cladding layer 3 has a thickness of approximately 0.15 to 0.2 μm, the active layer 4 has a thickness of approximately 0.05 μm, and the p-type cladding layer 5 has a thickness of 2 μm.
The camp layer 6 has a thickness of about 1 μm. The active layer 4 forms a heterojunction between the upper and lower cladding layers 3 and 5, forming a double heterojunction structure.

Next, as shown in FIG. 4, an insulating film 14 such as StO□ is partially formed on the main surface of the wafer 13 by a CVD (chemical vapor deposition) method.
Using Zn as a mask, zinc (Zn) is implanted into the surface of the wafer 13 corresponding to each resonator 7, and a diffusion layer 84 is formed that reaches halfway into the cladding layer 5, as shown by dots. This diffusion layer 8 serves as an ohmic layer for current confinement and a contact electrode.

Next, as shown in FIG. 5, such a wafer 13 is provided with an anode electrode 9 on its main surface and a cathode electrode 10 on its back surface. 7 Node electrode 9 is made of Cr/Au, cathode electrode 10 is made of AuGe
N i / P d / A u, all of which are formed by vapor deposition alloy.

Next, such a wafer 13 is divided vertically and horizontally at locations indicated by two-dot chain lines in FIG. 5, etc., and a large number of laser chips 12 as shown in FIG. 1 are manufactured.

According to such an embodiment, the following effects can be obtained.

(1) According to the present invention, a dummy channel is arranged outside a group of channels for forming a laser array, and a portion where the thickness of the active layer changes is generated in the dummy channel portion, and a resonator that emits laser light is formed. Since the thickness of the active layer is configured so as not to change in the portion corresponding to the channel for configuring the resonator, it is possible to obtain the effect that the light emitting characteristics in each resonator are constant.

(2) According to the above (1), according to the present invention, in manufacturing a semiconductor laser device, it is possible to manufacture a semiconductor laser device in which each resonator has constant light emission characteristics with good reproducibility.

(3) According to the above (1), according to the present invention, it is possible to provide a high-performance laser array.

(4) According to the above (1) to (3), according to the present invention, a high-output laser array can be manufactured with high yield;
A synergistic effect is obtained in that the manufacturing cost of the laser array can be reduced.

Although the invention made by the present inventor has been specifically explained based on Examples above, the present invention is not limited to the above Examples (although it is possible to make various changes without departing from the gist of the invention). Not even.

In the above explanation, the invention made by the present inventor was mainly applied to the manufacturing technology of a laser array having a csP type semiconductor laser structure, which is the background field of application, but the invention is not limited thereto. For example, it can be applied to a technology for manufacturing a laser array using a buried heterostructure semiconductor laser.

The present invention is applicable to at least a substrate having a structure in which there is a step on the main surface.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

Since the semiconductor laser device of the present invention has dummy channels arranged on both sides of the channel group used in the laser array, when a multilayer growth layer is formed on the channel by epitaxial growth, the thickness of the bottom layer will vary. Even if a step occurs, this step only appears on the dummy channel and does not appear on the channel provided to the laser array, so the thickness of each resonator is uniform and the laser light emitted from each resonator is characteristics become uniform. Therefore, a laser array can be manufactured with good reproducibility.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing a semiconductor laser device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a wafer having a channel in the same method for manufacturing a semi-quadram laser device, and FIG. 3 is a multilayer growth using epitaxial growth. Figure 4 is a cross-sectional view of a wafer with a diffusion layer provided on its main surface, Figure 5 is a cross-sectional view of a wafer with electrodes provided, and Figure 6 is a conventional laser. A schematic diagram showing the main parts of the array. FIG. 7 is a schematic diagram showing the same conventional laser array. 1... Channel, 2... Substrate, 3... Clad layer,
4... Active layer, 5... Craft layer, 6... Cap layer, 7... Resonator, 8... Diffusion layer, 9... Anode electrode, 10... Cathode electrode, 11 ... Dummy channel, 12... Semiconductor laser element (laser chip), 13... Wafer, 14... Insulating film, 15...
Thin wall portion, 16.17...thickness of the crat layer. Figure 1 Figure 3

Claims (1)

[Claims] 1. In a semiconductor laser device in which a channel for forming a semiconductor laser light emitting section is provided on the main surface of the substrate, dummy channels that do not become the semiconductor laser light emitting section are provided on both sides of the channel. Features of semiconductor laser device. 2. A method for manufacturing a semiconductor laser device, characterized in that a channel is provided on the main surface of the substrate and an epitaxial layer is formed on the channel, the method comprising: forming the channel on the main surface of the substrate; 1. A method of manufacturing a semiconductor laser device, comprising providing dummy channels on both sides of a channel, and then forming an epitaxial layer.