JPH07312456A - Quantum wire fabrication method - Google Patents

Abstract

(57) [Summary] [Objective] To provide a method for producing a quantum wire, which can improve the yield in producing a quantum wire. According to a method of manufacturing a quantum wire, {10 is formed on a surface of a semiconductor substrate having a quantum well structure formed of a multilayer film.
A 0} plane and a {111} plane are formed adjacent to each other, and dry etching is performed simultaneously in a state including both the {100} plane and the {111} plane. Further, in the above-mentioned method for producing a quantum wire, a taper-shaped mask having an end face that widens at the end is formed on the surface of a semiconductor substrate on which a quantum well structure is formed with the surface being a {100} plane, and dry etching is performed. Then, the {100} plane and the {111} plane are formed adjacent to each other on the surface of the semiconductor substrate. or,
In the above method for producing a quantum wire, a mask is formed on the surface of a semiconductor substrate on which a quantum well structure is formed in a state where the surface is a {100} plane, and wet etching treatment is performed,
A {100} plane and a {111} plane are formed adjacent to each other on the surface of the semiconductor substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing quantum wires.

[0002]

2. Description of the Related Art A method of manufacturing such a quantum wire is conventionally applied to a method of manufacturing a semiconductor laser device in which a groove having a V-shaped cross section is formed in a semiconductor substrate and a quantum well structure made of a multilayer film is formed on the groove. There was something I did. When a multilayer film is laminated on a semiconductor substrate having a groove having a V-shaped cross section in this way, the layer thickness of the multilayer film changes at a position above the tip of the V-shaped groove in the laminated multilayer film. However, because of the change in the layer thickness and the multilayer film being bent according to the V-shaped groove shape, the semiconductor laser device manufactured as described above has a quantum effect even in the direction parallel to the stacking plane. The light is confined in an extremely narrow area, forming a so-called quantum wire.

[0003]

However, in the above-mentioned conventional structure, since the variation in the layer thickness at the upper side of the tip of the V-shaped groove in the multilayer film has a great influence on the characteristics of the quantum wire, the multilayer film has Although it is necessary to suppress the variation in the laminated layer thickness, it is difficult to control with sufficient accuracy to suppress the variation in the characteristics of the quantum wires, and the production yield of the quantum wires is reduced. The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a method for manufacturing quantum wires, which can improve the manufacturing yield of quantum wires. The second purpose is to achieve the above-mentioned first purpose while simplifying the method for producing quantum wires.

[0004]

The first feature of the method for producing a quantum wire of the present invention is that the {100} plane and the {111} plane are formed on the surface of a semiconductor substrate having a quantum well structure formed of a multilayer film. The point is that they are formed adjacent to each other and are simultaneously dry-etched in a state including both the {100} plane and the {111} plane. The second feature is the above first feature,
A taper-shaped mask whose end face is widened is formed on the surface of a semiconductor substrate having a quantum well structure formed of a multilayer film in a state where the surface is a {100} surface, and the mask is applied after dry etching treatment. The point is that the {100} plane and the {111} plane are formed adjacent to each other on the surface of the semiconductor substrate after removal. The third feature is that in the first feature, the mask is formed on the surface of the semiconductor substrate having the quantum well structure formed of the multilayer film in the state where the surface is the {100} plane, and the wet etching treatment is performed. The point is that the mask is removed and the {100} plane and the {111} plane are formed adjacent to each other on the surface of the semiconductor substrate.

[0005]

According to the first feature of the present invention, when the {100} plane and the {111} plane formed adjacent to the surface of the semiconductor substrate are simultaneously dry-etched, the etching rate of the {100} plane becomes Since the etching rate of the {111} plane is higher than that of the {111} plane, the surface of the {100} plane is rapidly removed by etching, but the surface of the {111} plane is slower than the {100} plane. It is removed by etching. As a result, in the boundary portion between the {100} plane and the {111} plane, the {111} plane side remains relatively,
The {100} plane will be removed downward,
A wedge-shaped protrusion in a cross-sectional view is formed along the boundary line between the {100} plane and the {111} plane. The quantum well structure previously formed on the semiconductor substrate remains in the narrow portion near the tip of the protrusion, and the quantum well structure has a narrow width in the direction parallel to the stacking surface of the multilayer film forming the quantum well structure. It becomes a quantum wire. This wedge-shaped protrusion is {100}
Since it is formed by utilizing the difference in etching rate between the {111} plane and the {111} plane, the etching shape can be controlled with high accuracy.

According to the second feature of the present invention, when a dry etching process is performed by forming a tapered mask whose end face is wide on the {100} face, the mask itself is gradually removed by etching. During the etching process, the end face of the mask gradually recedes. A {111} plane appears in the recessed portion of the mask during etching, and since the etching rate of the {111} plane is small, once the {111} plane appears, it appears even if the etching process is continued. } The face is saved. If the mask is removed after this etching process,
A {100} plane and a {111} plane are formed adjacent to each other on the surface of the semiconductor substrate. Therefore, since the difference in etching rate between the {100} plane and the {111} plane is utilized, the {100} plane and the {111} plane can be in a state of being adjacent to each other with good controllability.

According to the third feature of the present invention, when a mask is formed on the {100} plane and wet etching is performed, the isotropic etching characteristic of the wet etching causes the lower portion of the edge of the mask on the semiconductor substrate to be removed. So-called side etching occurs in which the portion located on the side is removed by etching. As a result, a {111} plane is formed at the portion where the side etching occurs, and when the mask is removed after the wet etching treatment, {1} is formed on the surface of the semiconductor substrate.
The {00} plane and the {111} plane are formed adjacent to each other. Since the above mask does not need to be processed into a special shape, a simple process of forming a mask on the {100} plane and performing a wet etching process makes the {100} plane and the {111} plane mutually It can be in an adjacent state.

[0008]

According to the first feature described above, the etching shape affecting the characteristics of the quantum wire can be controlled with high precision,
Since it is possible to suppress the variation in the characteristics of the quantum wires, it has been possible to provide a method for manufacturing the quantum wires that can improve the production yield of the quantum wires. According to the second feature, {10
Since the 0} plane and the {111} plane can be in a state of being adjacent to each other, the present invention has provided a method for producing a quantum thin wire that can further improve the yield of quantum wire production. According to the third feature described above, a simple process of forming a mask on the {100} plane and performing a wet etching process can produce {10
Since the 0} plane and the {111} plane can be adjacent to each other, the effect of the first characteristic configuration can be obtained while simplifying the method of manufacturing the quantum wire.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a manufacturing process of a semiconductor laser device will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of a semiconductor laser element L manufactured by applying the method for manufacturing a quantum wire of the present invention, taken along a plane perpendicular to the cavity direction. In the semiconductor laser device L, a quantum well layer 3 having a quantum well structure including an n-type AlGaAs layer 2 and a multilayer film of an undoped GaAs layer and an undoped AlGaAs layer on an n-type GaAs substrate 1 has a substantially convex shape in cross section. Are formed on both sides of the protruding portion, and p-type AlGaAs
A buried layer 4 and an n-type GaAs buried layer 5 are formed, and a p-type AlGaAs layer 6 and a p-type GaAs layer 7 are formed on the upper side thereof.

When a current is injected from an electrode (not shown), the semiconductor laser device L oscillates in the quantum well layer 3 to emit laser light. That is, the structure shown in FIG. 1 emits two beams. The quantum well layer 3 is n
Formed on the AlGaAs layer 2 in a wedge shape in cross section,
Since it is narrow, it forms a so-called quantum wire.

The manufacturing process of the semiconductor laser device L having the above structure will be described below. First, as shown in FIG. 2, n-type AlG is formed on the {100} plane of a wafer-shaped n-type GaAs substrate 1.
The aAs layer 2 is laminated, and further, undoped AlGaAs
The quantum well layers 3 in which the layers 3a and the undoped GaAs layers 3b are alternately located are stacked. This stack is MBE, MO
The layers are stacked by a vapor phase growth method such as MBE or MOCVD. Next, as shown in the plan view of FIG. 3A and the cross-sectional view of FIG. 3B, on the surface of the semiconductor substrate S in which the quantum well layer 3 is laminated and the surface is the {100} plane, Longitudinal direction is <0 -1
1> (here, “−1” represents 1 bar in the Miller index), the stripe-shaped SiO ₂ mask 8 is subjected to photolithography and wet etching so that the end face becomes a tapered shape with a skirt extending. To form. As shown in FIG. 3B, there is one mask 8 with one element width in a sectional view perpendicular to the resonator direction.
As shown in FIG. 3, the elements are arranged at the same pitch as the width of one element in a sectional view perpendicular to the resonator direction.

When the mask 8 formed as shown in FIG. 3 is dry-etched on the mask 8 by a dry etching apparatus, a cross-sectional view shown in FIG. 4 is obtained.
The retreat of the mask 8 in the direction of arrow A and the {100} plane and {1}
Due to the difference in etching rate from the 11} plane, the slopes B of the {111} plane appear on both sides of the mask 8. When the dry etching process is continued from the state shown in FIG. 4 until the mask 8 disappears, as shown in FIG. 5, the upper surface portion C of the {100} plane appears from the position where the mask 8 is removed, and the surface of the semiconductor substrate S is exposed. The {100} plane and the {111} plane are adjacent to each other.

When the dry etching process is further continued from the state where the mask 8 shown in FIG. 5 has disappeared, the difference in etching rate between the {100} plane and the {111} plane causes {10}.
The 0} plane is rapidly etched, and the {111} plane is relatively gently etched, and as a result, the quantum well layer 3 is formed in a wedge shape in cross section as shown in FIG.
That is, the mask 8 is removed by a dry etching process so that the mask 8 shown in FIG.
That is, the etching process can be performed all at once without taking out from the dry etching apparatus until the time point when the quantum well layer 3 is formed into a wedge shape. As a result, the manufacturing process of the quantum wire can be simplified, and the wafer is not damaged by the processing outside the dry etching apparatus.

From the state shown in FIG. 6, the p-type AlGaAs burying layer 4 and the n-type GaAs burying layer 5 are laminated by liquid phase growth to a height corresponding to the top of the quantum well layer 3,
Further thereon, a p-type AlGaAs layer 6 and a p-type GaAs are formed.
Layer 7 is laminated. After that, electrodes are formed, and each element is separated from the wafer state to obtain a semiconductor laser element L.

[Other Embodiments] Other embodiments will be listed below. In the above-described embodiment, the SiO ₂ mask 8 is formed in a taper shape with the end face widened and a dry etching process is performed so that the {100} face and the {111} face are adjacent to each other. As shown in FIG. 8, a mask 20 of SiO ₂ is formed on the quantum well layer 3 in a stripe shape similar to that shown in FIG. 3A, and a wet etching process is applied to the mask 20 of the semiconductor substrate S shown in FIG. Mask 2 on the surface
The lower {100} plane and the {111} plane of 0 may be adjacent to each other. In this case, since the isotropic etching characteristic of the wet etching process is used, the mask 2
The shape of the end face of 0 does not need to be tapered, and the mask 2
It is easy to form 0.

In the above embodiment, the case where the present invention is applied to the manufacturing process of the semiconductor laser device is illustrated, but it can be applied to the manufacturing process of various semiconductor devices such as the manufacturing process of the optical integrated circuit.

In the above embodiment, SiO ₂ shown in FIG.
From the state in which the mask 8 is formed to the state shown in FIG.
Although the dry etching process is performed all at once, the mask 8 shown in FIG. 4 is taken out from the dry etching apparatus, the mask 8 is removed by etching, and then the mask 8 is returned to the dry etching apparatus to continue the dry etching. You can

Although two quantum wires are formed in the above embodiment, only one end face of the striped mask 8 shown in FIG. 3 is formed in a tapered shape, and then the same treatment as above is performed. You may make it form one quantum wire. From the state shown in FIG. 5, one of the two slopes B is removed by etching, and then dry etching is performed.
You may make it form one quantum wire.

In the above embodiment, the present invention is applied to AlGaA.
The case where it is applied to a semiconductor of an s-based material is illustrated, but
It can be applied to various semiconductor materials such as InGaAsP-based or InGaAlP-based materials.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the structure of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a sectional view of an element according to an embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing process according to an embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process according to an embodiment of the present invention.

FIG. 4 is a diagram showing a manufacturing process according to an embodiment of the present invention.

FIG. 5 is a diagram showing a manufacturing process according to an embodiment of the present invention.

FIG. 6 is a diagram showing a manufacturing process according to an embodiment of the present invention.

FIG. 7 is a diagram showing a manufacturing process according to another embodiment of the present invention.

FIG. 8 is a diagram showing a manufacturing process according to another embodiment of the present invention.

[Explanation of symbols]

 8 mask 20 mask S semiconductor substrate

Claims (3)

[Claims] 1. A {100} plane and a {111} plane are formed adjacent to each other on the surface of a semiconductor substrate (S) having a quantum well structure formed of a multilayer film, and the {100} plane and the {111} plane are formed. } A method of manufacturing a quantum wire in which dry etching is performed at the same time in a state including both surfaces. 2. A taper-shaped mask (8) whose end face is flared is formed on the surface of a semiconductor substrate (S) having a quantum well structure formed of a multilayer film with the surface being a {100} plane. After performing the dry etching treatment, the mask (8) is removed, and the surface of the semiconductor substrate (S) is {10
The method for producing a quantum wire according to claim 1, wherein the 0} plane and the {111} plane are formed adjacent to each other. 3. A mask (20) is formed on the surface of a semiconductor substrate (S) having a quantum well structure formed of a multilayer film in a state where the surface is a {100} plane, and a wet etching treatment is carried out. The method for producing a quantum wire according to claim 1, wherein the mask (20) is removed, and the {100} plane and the {111} plane are formed adjacent to each other on the surface of the semiconductor substrate (S).