JPH06140364A - Etching of semiconductor - Google Patents

Abstract

PURPOSE:To perform the high-quality etching of compound semiconductor without causing the overetching based on the relatively simple reactive ion etching method. CONSTITUTION:In the reactive ion etching method of the compound semiconductor, the etching is performed at a gas pressure under 1 Pa.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for etching a semiconductor by a reactive ion etching method (RIE method).

[0002]

2. Description of the Related Art Conventionally, in the case of etching a compound semiconductor such as GaAs, the RIE method is used to perform etching under a gas pressure of about 10 Pa in order to obtain anisotropy.

In such a conventional semiconductor etching method, even if the anisotropy is high, there is a limit, and a difference from a target pattern is generated to lower the etching pattern accuracy, or the etching end surface is roughened. In addition, undercut occurs and a vertical surface cannot be obtained.

Recently, laser light has been propagated in different directions in the ring laser section, and when an angular velocity acts on the ring laser section, the phase difference of the laser light in each direction changes accordingly. Focusing attention, the laser light in each direction is extracted from the ring laser unit and given to the light receiving unit to obtain an electrical signal corresponding to the phase difference of the laser light in each direction, so that the angular velocity acting on the ring laser unit is detected. Has been developed.

In such an optical angular velocity detector, the ring laser portion is formed by etching an epitaxial layer having a semiconductor laser structure into a rectangular ring shape or a triangular ring shape by the RIE method. I have to.

Then, the ring laser portion having the rectangular shape or the triangular shape is caused to satisfactorily propagate the laser light,
Further, in order to reduce the light loss, a mirror surface is formed by etching at the corner portion.

However, if such a ring laser portion is formed by the conventional etching method by RIE, the etching pattern accuracy is lowered, and the etching end surface is roughened or undercut occurs to obtain a vertical surface. It's gone, and you can't get good quality products.

Conventionally, there are RIBE method, ion milling method, CAIBE method and the like as a method for performing etching which can obtain anisotropy higher than that of RIE, but each of them requires a complicated apparatus structure for implementation. Therefore, it requires labor to maintain it.

[0009]

The problem to be solved is that if a relatively simple RIE method is used to perform anisotropic etching of a compound semiconductor such as GaAs under a gas pressure of about 10 Pa, Overetching causes a problem that the pattern accuracy of the etching is lowered, the end face of the etching is roughened, and undercutting occurs to make it impossible to obtain a vertical surface.

Further, the use of a special highly anisotropic etching method in which overetching does not pose a problem requires a complicated apparatus structure for its implementation.

[0011]

The present invention provides a RIE method under a low gas pressure of 1 Pa or less without causing overetching in order to perform high-quality etching of a compound semiconductor by a relatively simple RIE method. The etching of the compound semiconductor is optimized.

Further, in the present invention, in order to obtain a stable gas pressure of 1 Pa or less, SiC _{14 is used} as an etching gas.
It is characterized by using.

[0013]

1 and 2 show an example of the structure of a ring laser section in an optical angular velocity detector, which is formed in a rectangular ring shape by etching an epitaxial layer having a semiconductor laser structure. It is shown.

Laser light LB1 propagating in the clockwise direction and the counterclockwise direction generated inside the ring laser unit 1 by controlling the oscillation of the ring laser unit 1 at the outer portions of the respective corners of the ring laser unit 1 respectively. A mirror surface 2 is formed for favorably propagating LB2 and for reducing loss of laser light propagating in each direction.

When forming such a ring laser portion 1, as shown in FIG. 3, a buffer layer n (+) GaAs and an N layer nAlGaA are formed on a base substrate n (+) GaAs.
s, a light emitting layer AlGaAs, a P layer pAlGaAs, and a contact layer p (+) GaAs having a semiconductor laser structure in which they are sequentially laminated by epitaxial growth.
A ring-shaped etching is performed by anisotropic etching by the E method.

In the present invention, when the epitaxial layer having such a semiconductor laser structure is etched by the RIE method, the etching is carried out at a gas pressure of 1 Pa (7.5 mTorr) or less.

A plasma generator (RF application) driven at 13.56 MHz, which is usually used for carrying out the RIE method.
However, when the pressure of the etching gas is 1 Pa or less, the oscillation state becomes unstable and it is difficult to use it.

In this respect, if an appropriate etching gas is selected, a stable oscillation state can be obtained at a gas pressure of 1 Pa or less even in a normal plasma generator. In particular, SiCl ₄ is used as the etching gas. It turned out to be optimal.

However, according to the present invention, since the etching by the RIE method is performed under a low gas pressure, almost no over-etching occurs, and there is no difference from the target pattern, and the pattern accuracy of the etching is eliminated. Is improved, the etching end surface is not roughened, and a vertical surface can be obtained without undercut.

Therefore, when the epitaxial layer having the semiconductor laser structure is etched by the RIE method, SiC ₁₄ is used as an etching gas and the pressure is 1 Pa.
High anisotropy can be obtained by performing etching with the following low gas pressure, and as the ring laser portion 1, a ring having a vertical etching surface with no roughness and a rectangular ring with good pattern accuracy can be obtained. .

At this time, in particular, the mirror surface 2 formed on the outer side of each corner of the ring laser section 1 becomes favorable, which allows the laser light to propagate optimally in the length laser section 1 and also causes optical loss. Can be effectively reduced.

[0022]

As described above, in the semiconductor etching method according to the present invention, the compound semiconductor is optimally etched by the RIE method at a low gas pressure of 1 Pa or less without causing undercut or surface roughness. It is said that the etching of the compound semiconductor can be performed with high quality by a relatively simple RIE method without requiring a complicated apparatus configuration for implementation as in the case of the highly anisotropic etching method. Have advantages.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration example of a ring laser section in an optical angular velocity detector.

FIG. 2 is a perspective view showing a configuration example of a ring laser section in an optical angular velocity detector.

FIG. 3 is a sectional view showing an example of an epitaxial layer having a semiconductor laser structure.

[Explanation of symbols]

 1 Ring laser part 2 Mirror surface

Claims (2)

[Claims] 1. A reactive ion of a compound semiconductor
In the etching method, etching is performed at a gas pressure of 1 Pa or less, which is a semiconductor etching method. 2. The method for etching a semiconductor according to claim 1, wherein SiCl ₄ is used as an etching gas.