US 5,468,342 A · Method of etching an oxide layer

Abstract

A method of etching openings in oxide layers is disclosed. A hard mask layer is formed on the oxide layer. The hard mask layer is then patterned by a photoresist layer and an etch is performed to form openings in the hard mask. Next, the patterning layer may be removed and an etch is performed to remove the oxide in the regions defined by the hard mask layer openings. The etch with hard mask has minimized aspect ratio dependency, so that openings of different sizes may be formed simultaneously. An etch that may be carried out with Freon 134a (C.sub.2 H.sub.2 F.sub.4) to provide superior oxide:nitride selectivity is also disclosed. Additionally, the etch may be carried out at high temperature for improved wall profile without loss of selectivity. For deep openings, a two step etch process is disclosed, with a polymer clean step between the etches to remove polymer build up from first etch, and allow the etch to proceed to an increased depth.

Claims63

Dependent claims

A method of etching an oxide layer comprising the steps of:

providing a substrate having said oxide layer thereon;
depositing a hard mask layer on said oxide layer, wherein said hard mask layer comprises a material selected from the group consisting of silicon nitride, polysilicon, aluminum, a refractory metal, and a refractory metal silicide;
forming a patterning layer on said hard mask layer;
forming a patterning layer opening in said patterning layer to form a hard mask layer exposed region;
forming a hard mask layer opening in said hard mask layer exposed region to form an oxide layer exposed region;
and,
forming an oxide layer opening in said oxide layer exposed region by exposing said oxide layer exposed region to a plasma.

4 more elements

Dependencies are inferred from the claim text.

Method of etching an oxide layer

Life of this patent

Method of etching an oxide layer

Life of this patent

Abstract

Claims63