Patent ID: 11935889
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H | IPC H

Claim 9:
10. A method comprising:
forming a plurality of mask rings;
removing some portions of the plurality of mask rings;
in a first etching process, using remaining portions of the plurality of mask rings to etch a semiconductor substrate, wherein a first semiconductor strip and a second semiconductor strip are formed simultaneously, and the second semiconductor strip is in a semiconductor strip group comprising a plurality of semiconductor strips, and the plurality of semiconductor strips comprise bottoms at a first level;
forming a patterned photo resist to protect the first semiconductor strip and the semiconductor strip group, wherein the patterned photo resist comprises a first portion covering the first semiconductor strip, and the first portion of the patterned photo resist extends laterally beyond a first edge of the first semiconductor strip; and
in a second etching process, etching the semiconductor substrate to extend the first semiconductor strip deeper into the semiconductor substrate, wherein the first semiconductor strip comprises an upper portion formed by the first etching process, and a lower portion formed by the second etching process, and the lower portion comprises a second edge underlying and substantially flush with the first edge.