US 12,245,414 B2
Method of etching a memory stack by etching a blind hole
Runsheng Shen, Hefei (CN); Xifei Bao, Hefei (CN); and Changli Zhu, Hefei (CN)
Assigned to CHANGXIN MEMORY TECHNOLOGIES, INC., Hefei (CN)
Filed by CHANGXIN MEMORY TECHNOLOGIES, INC., Hefei (CN)
Filed on Mar. 3, 2022, as Appl. No. 17/653,428.
Application 17/653,428 is a continuation of application No. PCT/CN2021/120084, filed on Sep. 24, 2021.
Claims priority of application No. 202110291475.0 (CN), filed on Mar. 18, 2021.
Prior Publication US 2022/0302117 A1, Sep. 22, 2022
Int. Cl. H01L 27/108 (2006.01); H10B 12/00 (2023.01)
CPC H10B 12/03 (2023.02) 18 Claims
OG exemplary drawing
 
1. A method of etching a memory stack by etching a blind hole, comprising:
providing a substrate;
forming a film stack structure on the substrate, a top of the film stack structure being a cover layer;
forming a mask structure on the cover layer, the mask structure comprising a mask layer and a pattern transfer layer sequentially stacked from top to bottom;
performing a first etching on the mask structure to form first blind holes, the first blind holes running through the mask structure and terminating in the cover layer; and
performing a second etching on the mask structure to remove the mask layer, and to obtain a flatter top surface of the pattern transfer layer and wider bottom contours of the first blind holes than before the second etching.