Dry etching method

Adhesive bonding and miscellaneous chemical manufacture – Delaminating processes adapted for specified product – Delaminating in preparation for post processing recycling step

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Details

156657, 1566591, 156345, 252 791, B44C 122, C03C 1500, C03C 2506

Patent

active

052019942

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a dry etching method and, in particular, to a dry etching method in which the type of reactive gas used is improved and the selectivity between a workpiece being etched and a substance below the workpiece is increased.


BACKGROUND OF THE INVENTION



Description of the Prior Art

In the process of manufacturing ICs, the technique is known of superimposing various different films on top of a substrate of a substance such as silicon, then, using a plasma of a gas such as carbon tetrafluoride, perform dry etching to selectively remove parts of those films. Many different dry etching methods have been developed for this purpose, but the isotropy and high levels of selectivity of chemical dry etching methods make the widely used. In each of these chemical dry etching methods, a reactive gas is excited by microwaves in a plasma generation device to create an activated material, then this activated material is sent to a reaction chamber separated from the plasma chamber to react with, and hence etch, a workpiece within the reaction chamber, so the choice of reactive gas used for the etching is an important keypoint of such methods.
It is conventional practice to a use a mixture of carbon tetra-flouoride (CF.sub.4), oxygen (O.sub.2),k and nitrogen (N.sub.2) as this reactive gas.
However, this conventional technique of using a gas mixture of carbon tetrafluoride, oxygen, and nitrogen as the reactive gas causes a problem when the workpiece to be etched is a silicon nitride film, in that is difficult to selectively etch the silicon nitride film and not a silicon oxide film thereunder.
The present invention solves the above problem of the prior art, and it provides a dry etching method in which the selectively between a workpiece being etched and a substance below the workpiece is increased.


SUMMARY OF THE INVENTION

In order to achieve the above object, the dry etching method of the present invention is an etching method in which a work-piece to be etched is placed on a platen in a vacuum vessel, and a reactive gas activated by an activation means is used to etch the workpiece, wherein a gas mixture of a fluoride gas and a compound gas containing hydrogen as a constituent element is used as the reactive gas.
As the above fluoride gas, it is preferable to use one of CF.sub.4, NF.sub.3, or SF.sub.6. As the compound gas containing hydrogen as a constituent element, one of vaporized ethanol, methanol, or water, or even hydrogen itself, can be used.
According to the present invention, a gas mixture of a fluoride gas, oxygen, and a compound gas containing hydrogen as a constituent element can also be used as the reactive gas.
As described above, the present invention provides a dry etching method in which the use of a reactive gas comprising a mixture of a fluoride gas and a compound gas containing hydrogen as a constituent component greatly increases etching selectivity between a workpiece to be etched and a substance below the workpiece, enabling prevention of etching of the substance below the workpiece.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a dry etching device to which the dry etching method of the present invention can be applied;
FIG. 2 is an enlarged cross-section through a workpiece;
FIGS. 3 and 4 are graphs of etching selectivity against etching speed and mixing ratios of etching gases containing ethyl alcohol;
FIG. 5 is a graph of etching selectivity against etching speed and mixing ratios of etching gases containing hydrogen; and
FIG. 6 is a graph of etching selectivity against etching speed and mixing ratios of etching gases containing water.


DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the dry etching method of the present invention is described below with reference to the figures.
FIG. 1 shows an example of a dry etching device to which the dry etching method of the present invention can be applied.
In FIG. 1, reference number 1 denotes a vacuum vessel, and a platen 3 to support a workpiece to be etched 2 is provided within a

REFERENCES:
patent: 4462863 (1984-07-01), Nishimatsu et al.
patent: 4529476 (1985-07-01), Kawamoto et al.
patent: 4568410 (1986-02-01), Thornquist
patent: 4613401 (1986-09-01), Hoshino
patent: 4857140 (1989-08-01), Loewenstein

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