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

Claim 7:
8. A method for forming a hole structure having a first hole portion and a second hole portion connected to and over the first hole portion in a semiconductor device by using a single photolithography process, comprising:
forming a first etch mask directly on a stack structure, the first etch mask having a first mask opening that has a first lateral dimension, wherein forming the first etch mask comprises:
forming a hard mask layer over the stack structure and a soft mask layer over the hard mask layer;
patterning the soft mask layer using the photolithography process to from a first patterned soft mask layer; and
removing portions of the hard mask layer exposed by the first patterned soft mask layer to form a first patterned hard mask layer,

removing a portion of the stack structure exposed by the first etch mask to form an initial hole structure having an initial depth and the first lateral dimension;
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 etch mask, the second mask opening having a second lateral dimension greater than the first lateral dimension;
removing another portion of the stack structure exposed by the second mask opening to form a first initial hole portion having the first lateral dimension and a second initial hole portion having the second lateral dimension over and connected to the first initial hole portion; and
performing one or more of a time-controlled etch and a spectrum endpoint etch on the first and second initial hole portions until a bottom surface of the first initial hole portion reaches an etch stop layer of the stack structure, and the first initial hole portion and the second initial hole portion each reaches a respective depth of the first hole portion and the second hole portion, the first initial hole portion and the second initial hole portion respectively forming the first hole portion and the second hole portion, wherein the initial depth of the initial hole structure is equal to or greater than a depth of the second hole portion.