JPH06104220A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a dry etching method of a compound semiconductor device excellent in controllability, the substrate of which is not damaged and the underside of which is hardly roughened. CONSTITUTION:In the dry etching of a semiconductor material using an etching gas containing at least the mixed gas of hydrocarbon and hydrogen and a metallic material for an electrode, oxygen is added to the etching gas, thus preventing the formation of a hydrocarbon high-molecular film on a surface to be etched with excellent controllability, then reducing the roughness of an etched underside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dry etching a compound semiconductor material such as InP, InGaAsP, InGaAs and GaAs used for a semiconductor device and a metal material for electrodes such as copper and aluminum.

[0002]

2. Description of the Related Art Conventionally, InP and InGaAs containing In
Reactive ion etching using hydrocarbon and mixed gas of hydrocarbon and hydrogen has been reported as a method of dry etching of compound semiconductor materials such as P and InGaAs. Inst.Phy.Conf.Se by U.Niggebrugge and others
r.79, 367 (1985), and the 1991 Spring Meeting of Japan Society of Applied Physics 31p-K-10 by Irita et al.

In conventional reactive ion etching using hydrocarbons, hydrocarbons and hydrogen are introduced into an etching chamber and discharged with high frequency power. Decomposition of the etching gas by electric discharge forms active species and ions of methyl group, ethyl group, and hydrogen. It is considered that InP placed in the etching chamber is etched when In reacts with a methyl group or an ethyl group to become an organic metal, and P reacts with hydrogen to become a phosphine and volatilize. During etching, a hydrocarbon polymer film is synthesized on the etching mask. On the other hand, a hydrocarbon polymer film is not synthesized on InP and etching proceeds. By adjusting the ratio of the partial pressure of hydrocarbon and hydrogen, the total pressure, the high frequency power, and the bias voltage, the conditions under which the polymer film is formed on the mask but not on InP can be selected.

[0004]

In the reactive ion etching as described above, even if the polymer film is not formed on InP, fluctuations in the polymer film formation rate and spatial variations cause InP to be temporarily or locally generated. A polymer film is also formed on the top. Therefore, there is a problem that unevenness is likely to occur on the bottom surface of the etched InP. By adjusting the above-mentioned partial pressure ratio, total pressure, high frequency power, and bias voltage, it is possible to select conditions under which a polymer film is not easily formed on InP, but it is difficult to adjust each parameter independently and reproducibility is also high. There was a problem that it was scarce and it was difficult to obtain a good bottom surface with less roughness.

Further, for example, in Irita et al., Spring Meeting 31p-K-10 of the Japan Society of Applied Physics, it was reported that the addition of Ar to the etching gas improves the roughness of the bottom surface due to the sputtering effect. However Ar
The addition of Al is not always sufficient to reduce roughness, and there is a problem in that damage is newly added to the substrate by the impact of Ar ions.

The present invention has been made in order to solve the above-mentioned difficulties and problems, and it is possible to obtain a bottom surface which has good controllability and reproducibility and is sufficiently rough without damaging the substrate. An object of the present invention is to obtain a dry etching method for a semiconductor device.

[0007]

In a method of manufacturing a semiconductor device according to the present invention, in a dry etching of a semiconductor material and an electrode metal material using an etching gas containing at least hydrocarbon or a mixed gas of hydrocarbon and hydrogen. By adding oxygen to the etching gas, the roughness of the etching bottom surface is reduced.

[0008]

By adding oxygen to the etching gas, formation of a hydrocarbon polymer film during etching is suppressed and roughness on InP is reduced. This makes it possible to control the formation of the hydrocarbon polymer film independently of other etching conditions with good controllability, to form the polymer film on the mask with good reproducibility, and to form the polymer film on InP. You can choose the conditions not to be met. Since oxygen has a smaller mass than Ar, damage to the InP substrate due to ion bombardment does not pose a problem.

[0009]

【Example】

Example 1. FIG. 1 is a schematic view of an etching pattern based on a scanning electron microscope photograph of an InP substrate in which oxygen is added using a mixed gas of ethane and hydrogen and a silicon oxide film is used as an etching mask. FIG. 2 shows the case of etching without adding oxygen. Parallel plate type reactive ion etching was used for etching.
The etching conditions are a total pressure of 110 mTorr, an ethane partial pressure of 5.5 mTorr, a high frequency power of 0.6 W / cm ² , and an etching time of 60 minutes. Addition of oxygen with a partial pressure of 3.2 mTorr improves the roughness of the bottom surface as shown in FIG. The addition of oxygen suppresses the formation of hydrocarbon polymers and reduces the roughness on InP. InP by ion bombardment
Damage to the board is not a problem.

Embodiment 2. Although the above-described Example 1 shows an example of reactive ion etching using a mixed gas of ethane and hydrogen, the same gas can be used for other dry etching methods such as reactive ion beam etching. Also, when using an etching gas containing no hydrogen or an etching gas to which another gas is further added, the same effect can be obtained by adding oxygen. Also, an example in which the material to be etched is InP is shown, but InGaAsP, I
The same effect can be obtained when etching compound semiconductor materials such as nGaAs and GaAs and metallic materials such as copper and aluminum.

Embodiment 3. In the above-mentioned Example 1, an example under a certain condition by reactive ion etching using a mixed gas of ethane and hydrogen was shown. However, as the etching gas, the partial pressure of ethane gas was 5 to 10% of the total pressure. When a mixed gas is used, dry etching is possible in which a good bottom surface with less roughness can be obtained even in the range where the partial pressure of oxygen contained in the etching gas is 1 to 6% of the total pressure.

[0012]

As described above, the method of manufacturing a semiconductor device according to the present invention uses an etching gas in dry etching of a semiconductor material and an electrode metal material using an etching gas containing at least a mixed gas of hydrocarbon and hydrogen. By adding oxygen to the substrate, it is possible to obtain a sufficiently roughened etching bottom surface without damaging the substrate.

[Brief description of drawings]

FIG. 1 is a schematic view of an etching pattern according to the present invention.

FIG. 2 is a schematic diagram of an etching pattern when oxygen is not added.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuo Shiba 4-1-1 Mizuhara, Itami-shi Mitsubishi Electric Corp. Optical / Microwave Device Research Center

Claims (4)

[Claims] 1. A method of manufacturing a semiconductor device, wherein in the dry etching of a semiconductor material and an electrode metal material using an etching gas containing at least a mixed gas of hydrocarbon and hydrogen, the etching gas contains oxygen. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the dry etching method is reactive ion etching or reactive ion beam etching. 3. A semiconductor device according to claim 1 or 2, wherein a mixed gas of ethane and hydrogen in which the partial pressure of ethane gas is 5 to 10% of the total pressure is used as the etching gas. Manufacturing method. 4. The method for manufacturing a semiconductor device according to claim 3, wherein the partial pressure of oxygen contained in the etching gas is 1 to 6% of the total pressure.