JPS61141139A - Dry etching method for si material - Google Patents

Abstract

PURPOSE:To enable to perform an anisotropic etching on the material to be etched as well as to contrive improvement in the ratio of selectivity of the etching rate for resist by a method wherein a specific mixture gas is used as the processing gas for a dry etching. CONSTITUTION:An etching is performed using the mixed gas of the gas, having the molecular structure wherein a part of the fluorine of fluorocarbon is replaced with hydrogen and oxygen, or the mixed gas of fluorocarbon, hydrogen and oxygen, or the mixed gas of fluorocarbon, the gas having the molecular structure in which a part of the fluorine of fluorocarbon is replaced with hydrogen, and oxygen are used as the processing gas for the dry etching to be performed on an Si material. When the mixed gas such as above-mentioned is used for the dry etching to be performed on the Si material which will be used as the material to be etched, the material is anisotropically etched and the ratio of etching of the resist which becomes a mask when the etching is performed can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an excellent method for dry etching Si-based materials in the manufacturing process of electronic parts such as semiconductors.

Problems to be solved by conventional techniques and inventions Conventional S
For dry etching of i-based materials, particularly for dry etching of 81 nitride films, 7 Leon gas (trade name of DuPont) such as OF, or a mixed gas of several percent 01 added to Freon gas, has been used as the etching gas.

Freon gas is dissociated by high frequency discharge and generates fluorine radicals. These fluorine radicals chemically react with silicon and etching progresses. Several percent of O2 has been added to increase the amount of substances that contribute to etching (hereinafter referred to as etchants) or to remove carbon attached to the surface of Si-based materials.

However, as long as the fluorine radical reacts as an etchant, the object to be etched is etched isotropically, avoiding the occurrence of undercuts.

FIG. 1 shows the shape of an object to be etched after being etched under the following etching conditions as an example of a conventional etching method.

Etching device: Parallel electrode type plasma etching device Processing gas: 074 +10%O* Gas flow rate? 40800M Vacuum degree? 0.4 Torr ・High frequency output cuff 13.56 MHz 200W (0.64-W/♂) Object to be etched: Silicon nitride film (8000A) As is clear from Fig. 1, silicon is removed from the upper resist mask (1). It can be seen that undercutting of the nitride film (2) occurs. In the figure, (3) is an 81 board.

Also, the etching selection ratio (silicon nitride film etching rate/resist etching rate) at this time was 2.5.
Met.

There is a reactive ion etching method as a method for performing etching anisotropically. This method uses Freon ions, which are generated when Freon gas is dissociated by high-frequency discharge, as an etchant.

However, compared to fluorine radicals, 7-leon ions react with silicon much less frequently, and therefore the etching rate of the object to be etched is greatly reduced. Although the etching rate of the object to be etched can be increased by increasing the high-frequency power, reactive ion etching has a high sputtering property and causes great damage to the object to be etched and the underlying material.

Structure of the Invention The present invention provides a mixed gas of oxygen and a gas having a molecular structure in which part of the fluorine in carbon fluoride is replaced with hydrogen, or a mixed gas of carbon fluoride, hydrogen and oxygen, or carbon fluoride, A mixed gas of a gas having a molecular structure in which part of the fluorine in carbon fluoride is replaced with hydrogen and oxygen is used as a processing gas for dry etching of Si-based materials.

Function: When the mixed gas of the present invention is used for dry etching on a Si-based material to be etched, it has a unique effect of etching anisotropically and improving the etching selectivity with respect to the resist that serves as a mask during etching. produce an effect.

Embodiment FIG. 2 shows the shape of an object to be etched after being etched by the dry etching method of the present invention using the same etching apparatus as in the conventional example. In the figure, the same reference numerals as in FIG. 1 above indicate the same parts.

Etching device! [: Parallel electrode type plasma etching equipment processing effort and gas flow rate: OF, +10%0. 405
00M0HIF3 8 800M Degree of vacuum: 0.4 Torr High frequency power? 13.5 (iMHz 200W (0.64W/ai) Object to be etched: Silicon nitride film (8000A) As is clear from Figure 2, the silicon nitride film (1) is anisotropic with respect to the upper resist mask (1). You can see that it has been etched. Further, the etching selectivity (silicon nitride film etching rate/resist etching rate) at this time was 4.7.

Note that the above examples were carried out only when a mixed gas of carbon fluoride, a gas having a molecular structure in which part of the fluorine in the carbon fluoride was replaced with hydrogen, and oxygen was used as the etching gas. . However, when carbon fluoride, a gas with a molecular structure in which part of the fluorine in carbon fluoride is replaced with hydrogen, and a mixed gas with oxygen, or a mixed gas of carbon fluoride, hydrogen, and oxygen are used as the etching gas. However, the same effect is produced. Note that the same effect can be obtained with OH, F, , OH, ]F, in which a part of the fluorine in carbon fluoride is replaced with hydrogen.

On the other hand, although the object to be etched in the embodiment is a silicon nitride film, the same effect can be obtained if the object to be etched is silicon alone or a silicon compound.

Effects of the Invention The present invention enables anisotropic etching of the object to be etched by using the mixed gas of the present invention as a processing gas for dry etching in the trial etching of Si-based materials, and also makes it possible to select the etching rate for the resist. It has the effect of improving the ratio, and its practical effects are great.

[Brief explanation of drawings]

Figure 1 is a photograph of the cross-sectional shape of an object to be etched after etching a silicon nitride film using the conventional dry etching method, and Figure 2 is a photograph of the cross-sectional shape of an object to be etched after etching a silicon nitride film using the dry etching method according to the present invention. A photograph of the cross-sectional shape is shown. 1 Resist mask 2: Silicon nitride film 3: Si substrate Patent applicant: Matsushita Electric Industrial Co., Ltd. Representative Patent Attorney: Assistant Abe Continued Correction
Calligraphy (Kae) April 24, 1985

Claims (1)

[Claims] A mixed gas of oxygen and a gas with a molecular structure in which some of the fluorine in carbon fluoride is replaced with hydrogen, or a mixed gas of carbon fluoride, hydrogen, and oxygen, or a part of the fluorine in carbon fluoride and carbon fluoride. A dry etching method for Si-based materials, characterized in that a mixed gas of oxygen and a gas having a molecular structure in which some portions are replaced with hydrogen is used as a processing gas for dry etching.