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

Claim 12:
13. 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 by using a single photolithography process, comprising:
determining a hard mask layer, an etching resistivity of the hard mask layer to be 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 the 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 directly on the stack structure, the first patterned hard mask layer having 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 mask opening, including using an oxygen plasma etching process to form a second patterned soft mask layer and removing portions of the hard mask layer exposed by the second patterned soft mask layer to form a second mask opening in the first patterned hard mask layer, 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.