CPC C23C 16/56 (2013.01) [C23C 16/30 (2013.01); C23C 16/45529 (2013.01); H10B 12/02 (2023.02); H10B 12/30 (2023.02); H10B 41/20 (2023.02); H10B 41/35 (2023.02)] | 20 Claims |
1. A method comprising:
forming a film stack on a substrate, the film stack comprising a plurality of alternating layers of an oxide material and a nitride material and the film stack having a stack thickness;
etching the film stack to a first depth to form an opening with at least one sidewall and a bottom, the first depth being less than the thickness;
depositing a non-conformal liner on the at least one sidewall and the bottom of the opening, the non-conformal liner on the bottom of the opening having a thickness less than a thickness of the non-conformal liner on the at least one sidewall of the opening;
etching the non-conformal liner from the bottom of the opening to reduce the thickness of the non-conformal liner on the bottom of the opening;
selectively etching the film stack relative to the non-conformal liner to a second depth to form a hole; and
annealing the film stack in an oxidizing atmosphere to remove the non-conformal liner.
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