KR0141417B1 - Method of dry dtching for semiconductor compound the periodic table iii-v - Google Patents

Abstract

The present invention relates to a method of etching a III-V compound semiconductor of the periodic table by a dry process, the method of etching a semiconductor using both trialkylindium gas and hydrogen peroxide gas as an etchant at a semiconductor substrate temperature equal to or higher than the thermal dissociation evaporation temperature of the semiconductor. It is about.

According to the present invention, the use of trialkylindium gas and hydrogen peroxide gas as an etchant may be used as a potent etchant in the selective etching process of semiconductors in-line or in situ together with a metal organic molecular beam epitaxy device or a chemical beam epitaxy device using them. Can be utilized.

Description

Dry etching method of group III-V compound semiconductor of the periodic table

FIG. 1 is a pattern etching process of a gallium arsenide compound semiconductor substrate with hydrogen peroxide and trimethylindium gas at a substrate temperature of 600 ° C., and shows the result ((A) is a photograph of a Normalsky optical microscope and (B) is measured by a depth profiler). One profile).

FIG. 2 is a pattern etching of a gallium arsenide compound semiconductor substrate with only hydrogen peroxide gas or with hydrogen peroxide and trimethylindium gas at a temperature of 650 ° C., and the results are shown in a normal photomicrograph and an etching profile as shown in FIG. 1 ((A ) Is etched with hydrogen peroxide and trimethylindium gas,

(B) is etched only with hydrogen peroxide gas).

The present invention relates to a method of etching a III-V compound semiconductor of the periodic table. In particular, the present invention relates to a method of etching a compound group III-V compound semiconductor of the periodic table by a dry process, wherein both trialkylindium gas and hydrogen peroxide gas are used as an etchant at a semiconductor substrate temperature above the thermal dissociation evaporation temperature of the semiconductor. A method for etching a semiconductor.

Selective etching of semiconductor materials is one of the essential technologies for the development of new functional devices of three-wire structure such as quantum wire or quantum point, and also recently, multi-chamber UHV system As a result of the development of HF), many efforts have been made to form a vertically stacked quantum structure by an in-situ process without exposing the semiconductor specimen to the atmosphere, thereby increasing the need for such an etching technique.

Conventionally, as a selective etching technique by an in-situ process, a technique of performing pattern etching by irradiating a focused electron beam or an ion beam (FIB) to a chlorine gas (Cl ₂ gas) after irradiating a gallium oxide film is known. The use of chlorine gas creates problems such as corrosive problems in the chamber and vulnerability to mask materials such as indium oxide films.

In the present invention, a technique for easily etching a semiconductor has been found by using both hydrogen peroxide and trialkylindium gas as an etchant for the in-situ etching process and changing the substrate temperature of the semiconductor.

Accordingly, an object of the present invention is to provide a method of etching a group III-V compound semiconductor of the periodic table by a dry process, using both trialkylindium gas and hydrogen peroxide gas as an etchant at a temperature of a semiconductor substrate above the thermal dissociation evaporation temperature of the semiconductor. It is an object of the present invention to provide a method for etching a semiconductor.

According to one embodiment of the invention, the semiconductor material is a compound semiconductor composed of group III-V elements of the periodic table, of which gallium arsenide or indium is preferable.

According to another embodiment of the present invention, trialkylindium gas used simultaneously with hydrogen peroxide gas as an etchant is a semiconductor in a metal organic molecular beam epitaxy device or a chemical beam epitaxy device. It is used as one of epitaxial organometallics. The trialkyl indium gas is preferably trimethyl indium or triethyl indium gas.

According to another embodiment of the present invention, it is preferable to maintain the semiconductor substrate temperature above the thermal dissociation evaporation temperature of the semiconductor. The fact is that in the case of gallium arsenide as a semiconductor, the thermal dissociation evaporation temperature is 582 ° C., so that the semiconductor substrate temperature is 582 ° C. or higher.

The etching process of the group III-V compound semiconductor material consists of a chemical reaction by hydrogen peroxide gas of the following reaction formula, that is, the oxidation substitution evaporation of the group III metal:

2III-V + H ₂ O ₂ → Ⅲ ₂ O ↑ + V ₂ ↑ + H ₂ O ↑

(III is Ga, In, etc., V represents As, P, etc.).

In addition, by using hydrogen peroxide gas and trialkyl indium gas simultaneously, deposition of indium oxide film (In ₂ O ₃ ) formed above the thermal dissociation evaporation temperature of the semiconductor material and elemental evaporation due to oxidation substitution of the semiconductor surface by the oxide film. These schemes are as follows:

2In + 3H ₂ O ₂ → In ₂ O ₃ + 3H ₂ O ↑ and

In ₂ O ₃ + 4Ⅲ-Ⅴ → In ₂ O ↑ + 2Ⅲ ₂ O ↑ + 2Ⅴ ₂ ↑

Where III and V are as previously defined

As described above, according to the present invention, by using hydrogen peroxide gas and trialkyl indium gas simultaneously as an etchant, the semiconductor etching action by the hydrogen peroxide gas and the etching action of the semiconductor surface by the indium oxide film formed from these gases occur simultaneously.

The present invention will be described in more detail with reference to the following Examples.

The etching mask of the semiconductor wafer in this embodiment uses a carbon film known as a contamination resist. The mask pattern can be easily formed by depositing the carbon film on the surface of the semiconductor wafer (about 50 or less) and irradiating a focused electron beam in a trialkylindium gas atmosphere at room temperature. Therefore, a mask pattern is formed on the surface of the III-V compound semiconductor of the periodic table in a desired standard and used in this embodiment.

Example 1

An etching mask of a carbon film was prepared on the clean substrate surface of the gallium arsenide semiconductor, and then the semiconductor material was etched by introducing hydrogen peroxide and trimethylindium gas in an in-situ process. At this time, the width and spacing of the carbon mask pattern were formed from 10 μm to 1 μm, respectively, and the temperature of the semiconductor substrate was 600 ° C., and the flow rates of hydrogen peroxide and trimethylindium gas were 2.0 × 10 ⁻⁸ mol / s and 1.2 × 10, respectively. ^{It was set to -9} mol / s. The surface state of the semiconductor substrate after the etching was confirmed by normalsky optical micrographs and etching profiles. The results are shown in FIG.

FIG. 1 shows a typical state after etching of a gallium arsenide semiconductor substrate 2 having a carbon mask pattern 1, and a pattern width 3 and a pattern spacing (4) of 1 탆 from a Normalsky optical micrograph of FIG. 1A. ) Showed good separation. In addition, it can be seen from the etching profile of FIG. 1B that the etching slope 5 is shown well. At this time, the etching rate was good as about 1200 Pa / hr.

Example 2

Etching was carried out in the same manner as in Example 1 except that the semiconductor substrate temperature was set at 650 ° C., and the results are shown in FIG.

Comparative Example 1

Etching was performed in the same manner as in Example 2, except that only hydrogen peroxide gas was used instead of hydrogen peroxide and trimethylindium gas, and the results are shown in FIG. 2B as a Normalsky micrograph and etching profile.

FIG. 2 shows the results of Example 2 and Comparative Example 1, showing a Normalsky optical microscope photograph and an etching profile of pattern width (7) 10 μm and 5 μm at a pattern spacing (6) of 10 μm. Figure 2 shows the result of Example 2 and Figure 2B shows the result of Comparative Example 1. Comparing the etching rates from FIG. 2, the etching rate was about 2400 kPa / hr and about 650 kPa / hr, respectively, and the method of Example 2 according to the present invention showed an etching rate at least four times higher than that of Comparative Example 1. On the other hand, the edge change 8 of the etching pattern in FIG. 2 is due to the change of the carbon pattern due to the shaking during the electron beam scanning. The effect of thermal dissociation evaporation of gallium arsenide at this temperature is about 60 kW / hr as the etching rate, but negligible compared to the etching rate.

Thus, by simultaneously using hydrogen peroxide and trialkylindium gas as the etchant by the method according to the invention, the etching oil is further increased, thereby facilitating control thereof.

As described above, the use of trialkylindium gas and hydrogen peroxide gas as an etchant for the Group IIIV compound semiconductor of the periodic table can be performed in-line or in situ together with a metal organic molecular beam epitaxy device or a chemical beam epitaxy device using them. It can be used as a potent etchant in the selective etching process of semiconductors.

Claims (4)

A method of etching a III-V compound periodic table of the periodic table by a dry process, wherein a trialkylindium gas and a hydrogen peroxide gas are both used as an etchant at a semiconductor substrate temperature equal to or higher than the thermal dissociation evaporation temperature of the semiconductor. The etching method according to claim 1, wherein the semiconductor is gallium arsenide or indium. The etching method according to claim 1, wherein the trialkyl indium is selected from trimethyl indium and triethyl indium. The etching method according to claim 1, wherein the substrate is maintained at 582 占 폚 or higher when the semiconductor is gallium arsenide, or 360 占 폚 or higher when the semiconductor is indium.