Patent ID: 11876016
Assignee: YANGTZE MEMORY TECHNOLOGIES CO., LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method for forming a hole structure having a first hole portion and a second hole portion connected to and over the first portion in a stack structure of a semiconductor device, comprising:
determining a carbon content of a hard mask layer, such that an etching resistivity of the hard mask layer being inversely proportional to a difference between a first lateral dimension of the first hole portion and a second lateral dimension of the second hole portion, the first lateral dimension being less than the second lateral dimension;
forming the hard mask layer over the stack structure, and forming a soft mask layer on the hard mask layer;
patterning the soft mask layer using a photolithography process to form a first pattern over the hard mask layer;
patterning the hard mask layer by removing portions of the hard mask layer exposed by the first pattern of the soft mask layer to form a first patterned hard mask layer that has a first mask opening, the first mask opening having the first lateral dimension;
removing a portion of the stack structure exposed by the first patterned hard mask layer to form an initial hole structure in the stack structure;
after forming the initial hole structure, enlarging the first pattern of the soft mask layer and the first patterned hard mask layer, including using an oxygen plasma etching process to form a second pattern in the soft mask layer and removing portions of the hard mask layer exposed by the second pattern of the soft mask layer to form a second patterned hard mask layer that has a second mask opening, the second mask opening having the second lateral dimension; and
removing another portion of the stack structure exposed by the second patterned hard mask layer to form the hole structure.