Patent ID: 7781152
Filing Date: 2010-08-24
Classification: G03F

Abstract:
1. A method for forming, on a substrate, a bi-layer lift-off mask having a stencil layer with a projecting region having sharply defined edge and corner regions with sub-100 nm dimensions, comprising: providing a substrate; forming on said substrate a lower layer of PMGI or its derivatives; forming on said PMGI layer an upper layer of radiation sensitive resist material; exposing a first pattern portion of said upper layer of radiation sensitive resist material with a first dose of radiation, said first pattern portion having a narrow projecting region with parallel lateral edges terminating in a terminal transverse edge at two corner regions and an initial width W exposing a second pattern portion of said upper layer of radiation sensitive material with a second dose of radiation, said second pattern portion including an auxiliary pattern portion that partially overlaps said corner regions of said first pattern portion and which protects said corner region during subsequent processing and, when subsequently removed, will leave said corner regions sharply defined and with no supporting PMGI layer remaining beneath them; then developing said exposed first and second pattern portions of said upper layer, said developing process removing all unexposed portions of said upper layer as well as at least all portions of said lower PMGI layer not directly beneath said exposed upper layer and producing, thereby, an upper stencil shape including said first pattern portion with said auxiliary pattern pieces corresponding to said second pattern portion formed thereon and wherein there is an initial undercut of said PMGI layer relative to said upper layer producing a partial suspension of said upper layer; then performing an ozone oxidation process of said developed first and second pattern portions of said upper layer and said lower PMGI layer by placing said layers in the presence of an ozone oxidizing ambient within an oxidizing chamber wherein there is an ozone density, an ozone flow rate, an ozone oxidation processing time and a processing temperature, said ozone oxidation process, thereby, removing said auxiliary pattern pieces, forming and leaving behind sharply defined edge and corners on said first pattern portion of said stencil shape, reducing said stencil shape to a final width, W