JPH0821752B2 - Method for manufacturing semiconductor laser device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor laser device.

Conventional technology With the practical use of semiconductor lasers, compact disks,
Optical information processing equipment such as video discs has been realized and is in the stage of widespread use. By concentrating the current flowing in the vicinity of the active region of the semiconductor laser, it is possible to obtain characteristics such as low current operation that are easy to use in the information processing equipment. A typical structure for concentrating current in the active region is called an internal stripe type laser, and its sectional view is shown in FIG.

Hereinafter, a conventional internal stripe laser will be described with reference to the drawings. In FIG. 3, 12 is an n-type GaAs substrate, 13 is an n ⁺ -GaAs buffer layer, 14 is an n-Al _y Ga _1-y As clad layer, 15 is an Al _x Ga _1-x As active layer, 16 is a p- An Al _y Ga _1-y As clad layer, 17 is an n ⁺ -GaAs block layer, 19 is a p ⁺ -GaAs cap layer, 11 is an n-side electrode, and 21 is a p-side electrode.

The internal stripe type laser configured as described above is usually formed by crystal growth twice. That is, n-type
N ⁺ type GaAs buffer layer 13 and n type Al _y Ga _1-y As on GaAs substrate 12
The clad layer 14, the Al _x Ga _1-x As active layer 15, the p-type Al _y Ga _1-y As clad layer 16, and the n ⁺ -type GaAs block layer 17 are sequentially grown in the first growth. A stripe is formed by chemical etching using the n ⁺ type GaAs block layer 17 as a mask to expose the p type AlyGa _1-y As clad layer 16.
Next, as a second growth, a p-type Al _y Ga _1-y As clad layer 19,
A p ⁺ type GaAs cap layer 20 is grown, and ohmic electrodes 21 and 11 are formed on the p side and the n side. (+) on p-side, (-) on n-side
Voltage is applied, n ⁺ type GaAs block layer 17 and p type Al _y Ga
_A voltage is applied in the reverse direction only to the pn junction at the interface of the _1-y As clad layer 16 and to the other direction in the forward direction.
The current concentrates on the device, resulting in low current operation.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the internal stripe laser configured as described above, the formation of the internal stripe includes the steps of chemical etching, water washing, resist removal, and drying. Problems such as oxidation and contamination of the Al _y Ga _1-y As clad layer 16 surface occur. Oxidation of the regrowth interface and contamination with impurities bring about adverse effects such as a decrease in differential efficiency, an increase in forward voltage, and the appearance of negative resistance when a device is manufactured by performing the second growth thereafter.

In view of the above drawbacks, the present invention provides a method of manufacturing a semiconductor laser device using the RIE method or the RIBE method, which can suppress the oxidation at the regrowth interface and perform the second growth.

Means for Solving the Problems In order to solve the above problems, a method for manufacturing a semiconductor laser device according to the present invention is a method of manufacturing a single conductivity type Al _y Ga _1-y As on a _single conductivity type GaAs substrate by an epitaxial growth method. (0 <y ≦ 1)
A first cladding layer made of Al _x Ga _1-x As (0 ≦ x <1,
x <y) active layer, opposite conductivity type Al _y Ga _1-y As (0
<Y ≦ 1) second clad layer, one conductivity type GaAs
Sequentially forming a block layer made of Al _z Ga _1-z As (0 <z ≦ 1), and forming a resist mask having stripe-shaped openings on the mask layer, A step of removing at least the mask layer by etching to form a stripe-shaped groove; a step of removing the resist mask; a step of selectively etching the block layer by dry etching using the mask layer as a mask; A step of forming a groove reaching the clad layer, and a method of covering at least the stripe-shaped groove by an epitaxial growth method to form Al _y Ga _1-y As (0
<Y ≦ 1) and a step of sequentially forming a third clad layer made of <y ≦ 1) and a cap layer made of GaAs of the opposite conductivity type.

Operation With the above-mentioned configuration, the stripes are formed after the first growth, and when performing the second growth, the water washing process after the conventional chemical etching is not included, so that the oxidation and contamination of the regrowth interface can be suppressed. A good regrowth interface can be prepared.

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

FIG. 1 is a sectional view of a semiconductor laser device according to an embodiment of the present invention. In FIG. 1, 11 is an n-side electrode, 12 is an n-type GaAs substrate, 13 is an n-type GaAs buffer layer, 14 is an n-type Al _y Ga _1-y As clad layer, and 15 is an Al _x Ga _1-x As active layer. , 16
Is a p-type Al _y Ga _1-y As clad layer, 17 is an n-type GaAs block layer, 18 is an Al _z Ga _1-z As mask layer, 19 is a p-type Al _y Ga _1-y As clad layer, and 20 is p The GaAs cap layer 21 is a p-side electrode.

Next, a specific manufacturing method of the present invention will be described with reference to FIGS.
It will be described with reference to the drawings. First, MOCVD is performed on the n-type GaAs substrate 12.
Method is used to grow an n-type GaAs buffer layer 13 (thickness 0.5 μm), and then an n-type Al _y Ga _1-y As clad layer 14 (y = 0.3, thickness 1.0 μm), Al _x Ga _{1- x} As active layer 15 (x = thickness 0.1μ
m), p-type Al _y Ga _1-y As cladding layer 16 (y = 0.3, thickness 0.3)
μm), n-type GaAs block layer 17 (thickness 0.8 μm), Al _z Ga
_{A 1-z} As mask layer 18 (z = 0.3, thickness 0.2 μm) is sequentially grown. Next, a mask 22 having a width of 5 μm is applied on the mask layer 18 (FIG. 2 (a)). Then chemical etching (e.g. H ₂ SO _4:
The Al _z Ga _1-z As mask layer 18 is completely removed by H ₂ O ₂ : H ₂ O = 1: 8: 1) to form stripe-shaped grooves (FIG. 2 (b)). After that, the mask 22 is removed, and the GaAs block layer 17 is dry-etched by the RIE method or the RIBE method using the Al _z Ga _1-z As mask layer 18 from which the 5 μm-wide stripe portion is removed as a new mask. Gas used is CCl ₂ F ₂ 10sccm, gas pressure 0.06
Torr, RF power is 100W. Under these conditions, GaAs-Al
Since selective etching of GaAs is possible, it is shown in Fig. 2 (c).
As described above, the n-type GaAs block layer 17 is selectively etched and internal stripes can be formed. Finally, as shown in FIG. 1, the p-type Al _y Ga _1-y As cladding layer 1 was again formed by the MOCVD method.
9 (y = 0.3, thickness 1.2 μm) and p-type GaAs cap layer 20
(Thickness 1.0 μm) is grown to form n-side and p-side ohmic electrodes 11 and 21.

As described above, according to this embodiment, the AlGaAs
A mask is formed by the mask layer 18, and dry etching is performed under the selective etching conditions of the RIE method to grow the Al _y Ga _1-y As clad layer 16 from the exposed state for the second time. The second growth can be performed without the need for the resist removal and water washing steps while performing, and a good regrowth interface can be obtained.

Although the RIE method is used in this embodiment, the RIBE method may be used.

Further, in the present embodiment, the double heterostructure is followed by two layers of the opposite conductivity type and the uppermost layer, but there is no problem even if the multilayer structure is different in conductivity type and mixed crystal. .

EFFECTS OF THE INVENTION As described above, the present invention forms a current stripe by using dry etching with the uppermost layer of the first growth including a double hetero structure as a mask, thereby removing the resist required in the conventional chemical etching. The second growth can be performed without washing and drying steps. The fact that each of the above steps is unnecessary means that the AlGaAs surface exposed by etching is free from the conventional defects such as contamination by impurities during resist removal and oxidation in the water washing step, and a good regrowth interface is obtained. can get.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor laser device in one embodiment completed by the manufacturing method of the present invention, and FIGS. 2 (a) to 2 (c).
FIG. 3 is a manufacturing procedure diagram of a semiconductor laser device in an embodiment of the present invention, and FIG. 3 is a sectional view of a conventional internal stripe laser. 11 ... n-side electrode, 12 ... n-type GaAs substrate, 13 ... n-type GaAs
Buffer layer, 14 …… n-type Al _y Ga _1-y As cladding layer, 15 ……
Al _x Ga _1-x As active layer, 16-type p-type Al _y Ga _1-y As clad layer,
17 ... n-type GaAs block layer, 18 ... Al _z Ga _1-z As mask layer, 19 ... p-type Al _y Ga _1-y As clad layer, 20 ... p-type GaAs
Cap layer, 21 …… P-side electrode, 22 …… Mask.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Yoshikawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP 62-20323 (JP, A) JP 61-121487 (JP, A)

Claims (2)

[Claims] 1. A first clad layer made of Al _y Ga _1-y As (0 <y ≦ 1) of one conductivity type, Al _x Ga _1-x As (on an GaAs substrate of one conductivity type, by an epitaxial growth method. 0 ≦ x <1, x <
y) active layer of opposite conductivity type Al _y Ga _1-y As (0 <y
≤1), a second clad layer, a block layer made of GaAs of one conductivity type, and a mask layer made of Al _z Ga _1-z As (0 <z≤1), which are formed on the mask layer. Forming a resist mask having a stripe-shaped opening on the substrate, removing at least the mask layer by etching to form a stripe-shaped groove, removing the resist mask, and using the mask layer as a mask. A step of selectively etching the block layer by dry etching to form a groove reaching the second clad layer; and a step of covering at least the stripe-shaped groove with Al _y Ga _1-y As of opposite conductivity type by an epitaxial growth method. (0 <y
≦ 1) third clad layer and opposite conductivity type GaAs
And a step of sequentially forming a cap layer made of the same. 2. An MBE method or a MOCVD method for the epitaxial growth method.
The method of manufacturing a semiconductor laser device according to claim 1, wherein the method is used.