Selective wet etching of oxides

Abstract

The present invention relates to a wet etching composition including a sulfonic acid, a phosphonic acid, a phosphinic acid or a mixture of any two or more thereof, and a fluoride, and to a process of selectively etching oxides relative to nitrides, high-nitrogen content silicon oxynitride, metal, silicon or silicide. The process includes providing a substrate comprising oxide and one or more of nitride, high-nitrogen content silicon oxynitride, metal, silicon or silicide in which the oxide is to be etched; applying to the substrate for a time sufficient to remove a desired quantity of oxide from the substrate the etching composition; and removing the etching composition, in which the oxide is removed selectively.

Description

technical field [0001] The present invention relates to the wet etching of oxides that are selective to surrounding structures or materials, such as silicon dioxide, phosphorous doped silica glass (PSG), boron and phosphorous doped silica glass (BPSG), boron doped Silica glass (BSG) and silicon oxynitride with high oxygen content, the surrounding structures or materials include nitrides such as silicon nitride and titanium titanium and their mixtures, silicon oxynitride with high nitrogen content, metals, including polysilicon and monocrystalline silicon, silicides and photoresists. Background technique [0002] The lithography process generally consists of the following steps. First, a layer of photoresist (PR) material is applied to the surface of the wafer by a suitable method such as spin coating. The PR layer is then selectively exposed to radiation such as ultraviolet light, electrons, or X-rays, where the exposed area is defined by an exposure tool, mask, or compute...

AI Technical Summary

Problems solved by technology

[0007] A long standing problem with these conventional wet oxide etchants is their lack of selectivity

These wet etchants often attack surrounding structures, resulting in unwanted or unacceptable etch levels, or, particularly in the case of some photoresists, swelling and / or loss of adhesion to the photoresist-coated substrate. Attachment

As critical dimensions continue to be reduced, this lack of selectivity becomes less and less acceptable

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