US 12,148,655 B2
Methods for forming stairs in three-dimensional memory devices
Xiangning Wang, Wuhan (CN); Bin Yuan, Wuhan (CN); Chen Zuo, Wuhan (CN); Zhu Yang, Wuhan (CN); and Zongke Xu, Wuhan (CN)
Assigned to YANGTZE MEMORY TECHNOLOGIES CO., LTD., Wuhan (CN)
Filed by YANGTZE MEMORY TECHNOLOGIES CO., LTD., Wuhan (CN)
Filed on Jan. 29, 2021, as Appl. No. 17/162,937.
Application 17/162,937 is a continuation of application No. PCT/CN2021/071445, filed on Jan. 13, 2021.
Prior Publication US 2022/0223469 A1, Jul. 14, 2022
Int. Cl. H01L 21/768 (2006.01); H01L 23/522 (2006.01); H01L 23/528 (2006.01); H10B 41/27 (2023.01); H10B 43/27 (2023.01)
CPC H01L 21/76816 (2013.01) [H01L 21/76877 (2013.01); H01L 23/5226 (2013.01); H01L 23/5283 (2013.01); H10B 41/27 (2023.02); H10B 43/27 (2023.02)] 20 Claims
OG exemplary drawing
 
1. A method for forming a three-dimensional (3D) memory device, comprising:
forming a stack structure comprising interleaved a plurality of stack first layers and a plurality of stack second layers;
forming a stair in the stack structure, the stair comprising one of the stack first layers on a top surface;
forming a layer of sacrificial material comprising a first portion over a side surface of the stair and a second portion over the top surface of the stair;
forming a hard mask material layer over the layer of sacrificial material on the top and side surfaces of the stair;
performing a treatment the hard mask material layer to form a treated portion of the hard mask material layer laterally extending on the second portion of the layer of sacrificial material;
removing an untreated portion of the hard mask material layer covering the side surface of the stair to expose the first portion of the layer of sacrificial material;
using the treated portion of the hard mask material layer as an etch mask to partially remove the first portion of the layer of sacrificial material using an anisotropic etching process; and
removing a remaining portion of the first portion of the layer of sacrificial material using an isotropic etching process.