US 12,243,770 B2
Hard mask removal without damaging top epitaxial layer
Chanro Park, Clifton Park, NY (US); Yann Mignot, Slingerlands, NY (US); Daniel J. Vincent, Madison, WI (US); Su Chen Fan, Cohoes, NY (US); Christopher J. Waskiewicz, Rexford, NY (US); and Hsueh-Chung Chen, Cohoes, NY (US)
Assigned to International Business Machines Corporation, Armonk, NY (US)
Filed by International Business Machines Corporation, Armonk, NY (US)
Filed on Sep. 30, 2021, as Appl. No. 17/490,465.
Prior Publication US 2023/0095956 A1, Mar. 30, 2023
Int. Cl. H01L 21/768 (2006.01); H01L 21/02 (2006.01); H01L 21/3105 (2006.01); H01L 21/311 (2006.01); H01L 21/3213 (2006.01); H01L 29/78 (2006.01)
CPC H01L 21/76814 (2013.01) [H01L 21/0228 (2013.01); H01L 21/31053 (2013.01); H01L 21/31144 (2013.01); H01L 21/32134 (2013.01); H01L 21/76834 (2013.01); H01L 29/7827 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method, comprising:
etching vias and trenches in a middle-of-line (MOL) layer comprising a low-k dielectric layer, a sacrificial nitride layer, and a hard mask layer;
depositing a thin nitride layer within the vias and trenches;
depositing a carbon layer on the thin nitride layer within the vias and trenches;
etching back a top horizontal portion of the thin nitride layer to expose a portion of the hard mask layer, wherein the carbon layer protects a bottom horizontal portion of the thin nitride layer;
removing the hard mask layer while the carbon layer and the thin nitride layer protect the low-k dielectric layer and a top source/drain contact, wherein the thin nitride layer forms vertical portions above the sacrificial nitride layer;
removing the carbon layer; and
removing the thin nitride layer and the sacrificial nitride layer.