JPH02159082A - Manufacture of semiconductor laser - Google Patents

Abstract

PURPOSE:To reduce astigmatism and threshold current value and shorten the time required to manufacture by controlling the lengths of disordered regions to be not larger than several mum's. CONSTITUTION:Successively formed on a substrate 1 consisting of an n-type GaAs are a first clad layer 2 consisting of an n-type AlxGa1-xAs, a superlattice layer 3 consisting of AlyGa1-yAs-GaAs, a second clad layer 4 consisting of p-type AlxGa1-xAs, and a contact layer 5 consisting of p-type GaAs. A resist film 11 is formed on the contact layer 5, and a stripe-shaped opening 13 is provided. Then, dry etching out using the resist film 11 as a mask to form an etched mirror surface 10. A film 9 consisting of an impurity is formed on a wafer. Then, the resist film 11 is removed. At that time, the film 9 is also peeled off. The impurity is diffused through the etched mirror surface 10 into the element by thermal diffusion using the film 9 as a diffusion source. At that time, the superlattice layer 3 is disordered by the impurity and a region 6 having so called window structure is formed. The length of the region 6 is easily controlled by the condition during the thermal diffusion.

Description

[Detailed Description of the Invention] [Industrial Application Field] The invention of B relates to a method of manufacturing a semiconductor laser with a window structure that enables higher performance and higher output.

(Prior Art) Fig. 2 is a cross-sectional view showing the structure of a conventional semiconductor laser disclosed in, for example, Japanese Unexamined Patent Publication No. 60-101989. In this figure, 1 is a substrate made of n-type GaAs; 2 is a first cladding layer made of n-type A I
A superlattice layer composed of aAs, 4 is a p-type Aj.

Second cladding layer made of Go, □As, 5 is p-type GaA
6 is a region in which the superlattice is disordered, 7 is an impurity diffusion region, 8a is a p electrode, 8bt, t
nfI pole, 15 is the interfold plane.

Next, the operation will be explained.

When a voltage is applied to the pn junction between the ppn electric currents eN+88 and 8b in the forward direction relative to the C, a current is injected into the superlattice layer 3 and light is emitted. The laser beam is guided by the difference in refractive index between the superlattice layer 3 and the first cladding layer 2 and second cladding layer 4, and is oscillated by a resonator formed by opposing or apertured surfaces 15. Koru.

In this configuration, the forbidden band width of the region 6 disordered by impurity diffusion is larger than the effective forbidden band width of the superlattice layer 3, and the laser beam emitted from the superlattice layer 3
The disordered region 6 has a so-called window structure in which almost no absorption occurs. A short wavelength band semiconductor laser mainly made of At1GaAs having such a window structure determines the maximum optical output and lifetime, prevents deterioration even at the aperture 15, and is capable of high output operation.

3(a) to 3(e) are cross-sectional views for explaining a conventional method of manufacturing the semiconductor laser shown in FIG. 2. In these figures, the same reference numerals as in FIG. 2 indicate the same parts, 12 is a Si, N4 film, and 13 is a striped opening.

Next, the manufacturing process will be explained. .

First, as shown in FIG. 3(a), layers from the first cladding N2 to the contact layer 5 are sequentially formed on the substrate 1 by, for example, a vapor phase growth method such as an MO-CVD method, or an MBE method. Next, as shown in FIG. 3(b), a Si, N, film 12 is formed on the contact layer 5, and a striped area 1-1 is etched using photolithography and etching techniques.
Further, Zn is diffused through this opening 13 to form an impurity diffusion region 7.
The superlattice jM3 within is assumed to be a uniformly disordered region 6.

Next, after removing the Si, N, and film 12 as shown in FIG. 8a
, 8b. Then, after forming a multilayer surface 15 that functions as a resonator by opening the chip, it is separated into each chip.

[Problems that the invention attempts to solve]

In the conventional semiconductor laser as described above, since a resonator is formed by a gap, the length t of the disordered region 6 is
1 defined by the mechanical precision of the zBg opening, whereas this method by opening the disordered region 6
It is usually necessary to set the length l to 10 μm or more, and it is difficult to precisely control this length. For this reason, there have been problems such as an increase in astigmatism and an increase in oscillation threshold voltage. In addition, in the manufacturing process, the diffusion distance from the surface to the active layer is long, 3 μm or more, so there was a problem with controllability in the depth direction1.Therefore, in order to solve these problems, a patent application filed in Sho 61 In Japanese Patent No. 315097, after etching from the contact layer to the lower cladding layer or the vicinity of the active layer, impurity diffusion is performed from this etched surface.
ion? - A method for performing F person etc. has also been proposed. However, this method has a problem in that it takes a long time to manufacture. .

This invention was made to solve this problem, and by controlling the length of the disordered region by several μmm, it is possible to reduce aste and fgmatism.
Another object of the present invention is to provide a method for manufacturing a semiconductor laser that can reduce the threshold voltage and shorten the time required for manufacturing.

[Top means to solve problems]

A method for manufacturing a semiconductor laser according to the present invention includes the steps of growing a first cladding layer, a superlattice layer or a bulge well layer, and a second cladding layer on a semiconductor substrate, and growing a first cladding layer from above the second cladding layer. A step of forming a groove by etching up to the layer and forming an etched mirror surface that will serve as a resonance suppressing end surface, and forming a film made of impurities on this etched mirror surface.
This process includes a step of disordering a part of the superlattice +1 or quantum well layer using this film as a diffusion source, and a step of separating each chip. .

[Effect]

In this invention, impurities diffused from the film formed on the etched mirror surface form a superlattice layer or a quantum layer.
A portion of the layer is disordered to form a window structure region, and the length of the window structure region is controlled by diffusion humidity, time, etc. 1 [Example] FIG. 1 is a sectional view for explaining an example of the method for manufacturing a semiconductor laser of the present invention.

In these figures, the same reference numerals as in FIG.
4 is a deposition beam.

Next, the manufacturing process will be explained.

First, as shown in FIG. 1(a), an n-type A! , Gn+-As
The first '/;77 F layer 2. At'V a
Composed of l-yAs-GaAs, t = superlattice layer 3゜p
A second Cla-Rad layer 4 consisting of A1wGa, As,
Each layer of the contact layer 5 made of p-type GaAs is sequentially formed 1. After the growth, a resist film 11 (or an insulating film) is formed on the contact layer 5 as shown in FIG. - Provide a striped opening 13 in the shaft 11.

Next, register the 8L sea urchin shown in FIG.
Dry etching is performed using FtlE) as a mask to form the surface 10.

After the edging, as shown in FIG.
is 1, which becomes a diffusion source of impurities in the next diffusion process, and y! During A deposition, when the focused beam 14 hits the wafer from the vertical direction, the film 9 is formed only on the wafer curve, that is, on the top of the Renost film 11, and is hardly formed on the etched mirror surface 10. Therefore, by applying the vapor deposition beam 14 to the wafer from an oblique direction, the wafer-formed IjFJII portion 13 is coated with a wafer.
A film 9 is formed on 0.

Thereafter, as shown in FIG. 1(e), the resist film 11 is removed. At this time, the film 9 formed on the resist film 11
The resist film 11 is also peeled off together with the resist film 11. .

As shown in FIG. 1(f), after the resist film 11 is peeled off, impurities are diffused into the device through the etched mirror surface 10 by thermal diffusion using the film 9 as a diffusion source. At this time, the superlattice layer 3 becomes disordered due to impurities, and a so-called window structure region 6 is formed. The length I of the region 6 of this window structure can be easily controlled by the conditions during heat diffusion, that is, the diffusion temperature and diffusion time. Desirable impurities include Sl, Zn, etc., which can easily disorder the superlattice layer 3 by thermal diffusion.

Finally, a p-electrode 8a1 is placed on the contact layer 5 on the substrate 1 side.
The electrode is formed by steaming, sorrel, ivy, etc.
By separating the wafer into seeds along the striped openings 13, a device as shown in FIG. 1(g) is completed.

The operation of the semiconductor laser obtained by this invention is similar to that of the conventional one. However, the length l of the disordered region 6 of the superlattice, which is determined in the manufacturing process, can be determined by the depth of diffusion by the impurity from the sotido mirror direction 10, and the length e is It can be easily controlled to 1 μm or less depending on the conditions.

Therefore, it is possible to easily obtain a semiconductor laser which has characteristics such as low astigmatism and low oscillation threshold current, and which is capable of high output operation due to the window structure.

In particular, the LS5μm and low astigma differential f-ism,
A semiconductor laser with a low threshold current can be obtained.

In addition, unlike conventional semiconductor L/-Zers, it does not require technology to accurately diffuse into an area of several μm from the surface.
The device yield will also be dramatically improved. .

In particular, since the vapor-deposited film 9 is used as a diffusion source,
It is suggested that this film 9 can also be used as an end face protection film as it is.
The end face protection film forming process can be simplified.

In addition, in the above example, A I G a A s -G
Although only the superlattice layer composed of aAs has been explained, Ae, Ga, -XAs-AJlyGal-
The same can be applied to a superlattice layer composed of yAs (x'f-y) superlattice layers.

It goes without saying that the present invention can also be applied to semiconductor lasers having superlattice layers or multiple quantum well layers made of materials other than those mentioned above.

〔Effect of the invention〕

As explained above, Party B's invention includes a first semiconductor substrate on a semiconductor substrate.
cladding layer, superlattice layer or quantum well layer.

A step of growing a second cladding layer, a step of forming a groove by etching from the second cladding layer A to the first cladding layer to form an etched mirror surface that will become a resonator end face, and a step of forming an etched mirror surface on the etched mirror surface. The process includes forming a film consisting of a film of In addition to being able to easily control the length of the region depending on the conditions during thermal diffusion, a film made of impurities can be used as an end face protection film, which has the effect of shortening the manufacturing process.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the semiconductor laser manufacturing method of the present invention, FIG. 2 is a cross-sectional view showing the structure of a conventional semiconductor laser, and FIG. 3 is a cross-sectional view showing the structure of a conventional semiconductor laser. FIG. 2 is a cross-sectional view showing a manufacturing method. In the figure, 1 is an n-type GaAs substrate, 2 is a II-type At)
, Gn, -xAs first cladding layer, 3 is AIIVGa,
-Superlattice layer composed of As-GaAs, 4-bar ρ type A/
, Ga, -, As second cladding layer, 5 p-type GaAs concrete layer 1, 6 is a region in which the superlattice is disordered, 7 is an impurity diffusion region, 8a is a p-type electrode, 8b is an n-type electrode, 9
10 is a film made of impurities, 10 is an etched mirror surface, 11 is a resist l-film, 13 is a striped opening, and 14 is a vapor deposition beam. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] a step of growing a first cladding layer, a superlattice layer or a quantum well layer, and a second cladding layer on the semiconductor substrate;
A step of forming a groove by etching from the top of the cladding layer to the first cladding layer to form an etched mirror surface that will become the end face of the cavity, and forming a film made of impurities on this etched mirror surface and diffusing this film. 1. A method for manufacturing a semiconductor laser, comprising the steps of: disordering part of the superlattice layer or quantum well layer as a source; and separating each chip.