Patent ID: 11929254
Assignee: TAIWAN SEMICONDUCTOR MANUFACTURING COMPANY LTD.
Field: Semiconductors (Electrical engineering)
Classification: CPC H  Y | IPC H

Claim 15:
16. A method comprising:
depositing a first oxide layer over a semiconductor layer;
depositing a second oxide layer over the first oxide layer, wherein the second oxide layer has a greater density than the first oxide layer;
forming a plurality of mandrels over the second oxide layer;
forming spacers on sidewalls of the plurality of mandrels;
removing the plurality of mandrels to define openings between the spacers, wherein removing the plurality of mandrels partially etches recesses in the second oxide layer, and wherein a portion of the second oxide layer remains under the recesses after removing the plurality of mandrels;
using the spacers as a mask to pattern the first oxide layer; and
using the first oxide layer as a mask to pattern the semiconductor layer.