US 12,245,434 B2
Method of making a three-dimensional memory device using composite hard masks for formation of deep via openings
Monica Titus, Santa Clara, CA (US); Roshan Jayakhar Tirukkonda, Milpitas, CA (US); Senaka Kanakamedala, San Jose, CA (US); and Raghuveer S. Makala, Campbell, CA (US)
Assigned to Sandisk Technologies, Inc., Milpitas, CA (US)
Filed by SANDISK TECHNOLOGIES LLC, Addison, TX (US)
Filed on Feb. 1, 2022, as Appl. No. 17/590,278.
Application 17/590,278 is a continuation in part of application No. 17/508,036, filed on Oct. 22, 2021.
Application 17/508,036 is a continuation in part of application No. 17/494,114, filed on Oct. 5, 2021.
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 2022/0208776 A1, Jun. 30, 2022
Int. Cl. H10B 43/35 (2023.01); H10B 41/10 (2023.01); H10B 41/35 (2023.01); H10B 43/10 (2023.01)
CPC H10B 43/35 (2023.02) [H10B 41/10 (2023.02); H10B 41/35 (2023.02); H10B 43/10 (2023.02)] 20 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 composite hard mask layer over the alternating stack, wherein the composite hard mask layer comprises a layer stack including a lower patterning film, a first cladding material layer overlying the lower patterning film, and an upper patterning film overlying the first cladding material layer;
forming a patterned photoresist layer including openings therethrough over the composite hard mask layer;
forming openings in the hard mask layer by performing a hard-mask-open anisotropic etch process that transfers a pattern of the openings in the photoresist layer through the hard mask layer; and
forming via openings through the alternating stack by performing an anisotropic etch process that transfers a pattern of the openings in the composite hard mask layer through the alternating stack,
wherein the upper patterning film functions as an etch mask at least during an initial phase of the anisotropic etch process and the first cladding material layer functions as an etch mask at least during a subsequent phase of the anisotropic etch process, and wherein the first cladding material layer has higher etch resistance than the upper patterning film and the lower patterning film during the anisotropic etch process.