CPC H01L 21/76802 (2013.01) [H01L 21/02167 (2013.01); H01L 21/02211 (2013.01); H01L 21/02274 (2013.01); H01L 21/0228 (2013.01); H01L 21/0337 (2013.01); H01L 21/31144 (2013.01); H01L 21/76879 (2013.01)] | 20 Claims |
1. A method comprising:
forming a tri-layer structure over a substrate, the tri-layer structure comprising an upper layer, a middle layer, and a bottom layer;
patterning the upper layer to form a first mask pattern, the first mask pattern comprising a first opening;
depositing a film over the first mask pattern and the middle layer and within the first opening, wherein the film comprises a first portion and a second portion, the first portion of the film being on a top surface of the first mask pattern and having a first thickness, the second portion of the film being on a sidewall of the first mask pattern, the second portion of the film having a second thickness proximate the top surface of the first mask pattern and a third thickness distal the top surface of the first mask pattern, the first thickness being greater than the third thickness;
performing a descum process in the first opening, wherein performing the descum process in the first opening partially removes the middle layer; and
etching the middle layer using the first mask pattern and remaining portions of the film as an etching mask to form a second mask pattern.
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