US 12,250,817 B2
Method of making a three-dimensional memory device using composite hard masks for formation of deep via openings
Katsufumi Okamoto, Yokkaichi (JP); and Monica Titus, Santa Clara, CA (US)
Assigned to Sandisk Technologies, Inc., Milpitas, CA (US)
Filed by SANDISK TECHNOLOGIES LLC, Addison, TX (US)
Filed on Oct. 5, 2021, as Appl. No. 17/494,114.
Application 17/494,114 is a continuation in part of application No. 17/355,955, filed on Jun. 23, 2021, granted, now 11,972,954.
Application 17/355,955 is a continuation in part of application No. 17/136,471, filed on Dec. 29, 2020, granted, now 12,010,841.
Prior Publication US 2022/0208788 A1, Jun. 30, 2022
Int. Cl. H10B 43/27 (2023.01); H10B 41/27 (2023.01)
CPC H10B 43/27 (2023.02) [H10B 41/27 (2023.02)] 19 Claims
OG exemplary drawing
 
1. A method of forming a semiconductor structure, comprising:
forming an alternating stack of first material layers and second material layers over a substrate;
forming a hard mask layer over the alternating stack;
applying and patterning a photoresist layer over the hard mask layer, wherein openings are formed in the photoresist layer;
forming cavities in the hard mask layer;
forming a cladding liner on sidewalls of the cavities in the hard mask layer;
forming via openings in the alternating stack by performing an anisotropic etch process that transfers a pattern of the cavities in the hard mask layer through each layer within the alternating stack employing a combination of the cladding liner and the hard mask layer as an etch mask;
forming a memory film and a vertical semiconductor channel in each respective via opening; and
replacing the second material layers with electrically conductive word lines to form a three-dimensional memory device.