公开(公告)号：US11810786B2

公开(公告)日：2023-11-07

申请号：US17385969

申请日：2021-07-27

Applicant: UNITED MICROELECTRONICS CORP.

Inventor： Po-Wen Su ,  Cheng-Han Lu

IPC: H01L21/027 ,  H01L21/768 ,  H01L21/3213 ,  H01L21/033 ,  H01L21/311 ,  H01L21/308

CPC classification number: H01L21/0274 ,  H01L21/0337 ,  H01L21/3086 ,  H01L21/31144 ,  H01L21/32139 ,  H01L21/76816 ,  H01L21/76892

Abstract: A method for fabricating a semiconductor device includes following steps: A patterned mask layer including a plurality of standing walls and a covering part is formed on a surface of a semiconductor substrate, wherein two adjacent standing walls define a first opening exposing a part of the surface, and the covering part blankets the surface. A first patterned photoresist layer is formed to partially cover the covering part. A first etching process is performed to form a first trench in the substrate, passing through the surface and aligning with the first opening. A portion of the patterned mask layer is removed to form a second opening exposing another portion of the surface. A second etching process is performed to form a second trench in the substrate and define an active area on the surface. The depth of the first trench is greater than that of the second trench.