Patent ID: 11877449
Assignee: YANGTZE MEMORY TECHNOLOGIES CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method for forming a three-dimensional (3D) memory device, comprising:
forming a channel hole extending vertically above a substrate and having a plum blossom shape in a plan view;
sequentially forming a blocking layer, a charge trapping layer, a tunneling layer, and a semiconductor channel layer each following the plum blossom shape along sidewalls of the channel hole;
forming an etch stop layer over the semiconductor channel layer, such that an apex thickness of the etch stop layer at each apex of the plum blossom shape is greater than an edge thickness of the etch stop layer at edges of the plum blossom shape;
removing parts of the etch stop layer at the edges of the plum blossom shape to expose parts of the semiconductor channel layer at the edges of the plum blossom shape;
removing the parts of the semiconductor channel layer at the edges of the plum blossom shape to separate the semiconductor channel layer into a plurality of semiconductor channels each at a respective apex of the plum blossom shape; and
forming a capping layer to fill the channel hole,
wherein after the formation of the capping layer, a channel structure having the plum blossom shape is formed, which comprises:
the blocking layer, the charge trapping layer, and the tunneling layer, each of which is continuous and nominally uniform in the plan view;
the plurality of semiconductor channels; and
the capping layer.