Technique to deposit sidewall passivation for high aspect ratio cylinder etch

摘要

Various embodiments herein relate to methods, apparatus and systems for forming a recessed feature in dielectric material on a semiconductor substrate. Separate etching and deposition operations are employed in a cyclic manner. Each etching operation partially etches the feature. Each deposition operation forms a protective coating on the sidewalls of the feature to prevent lateral etch of the dielectric material during the etching operations. The protective coating may be deposited using methods that result in formation of the protective coating along substantially the entire length of the sidewalls. The protective coating may be deposited using particular reactants having low sticking coefficients in some embodiments. The protective coating may also be deposited using particular reaction mechanisms that result in substantially complete sidewall coating. In some cases the protective coating is deposited using plasma assisted atomic layer deposition or plasma assisted chemical vapor deposition.

主权项

1. A method of forming an etched feature in dielectric material on a semiconductor substrate, the method comprising:
(a) generating a first plasma comprising an etching reactant, exposing the substrate to the first plasma, and partially etching the feature in the dielectric material; (b) after (a), depositing a protective film on sidewalls of the feature, wherein the protective film is deposited along substantially the entire depth of the feature through a plasma assisted atomic layer deposition reaction comprising:
(i) exposing the substrate to a first deposition reactant and allowing the first deposition reactant to adsorb onto the sidewalls of the feature;(ii) after (i), exposing the substrate to a second plasma comprising a second deposition reactant, wherein exposing the substrate to the second plasma drives a surface reaction between the first deposition reactant and the second deposition reactant, thereby forming the protective film on the sidewalls of the feature; and (c) repeating (a)-(b) until the feature is etched to a final depth, wherein the protective film deposited in (b) substantially prevents lateral etch of the feature during (a), and wherein the feature has an aspect ratio of about 5 or greater at its final depth.