公开(公告)号：US20240112914A1

公开(公告)日：2024-04-04

申请号：US18121609

申请日：2023-03-15

Applicant: University of Electronic Science and Technology of China

Inventor： Bo ZHANG ,  Teng LIU ,  Wentong ZHANG ,  Nailong HE ,  Sen ZHANG ,  Ming QIAO ,  Zhaoji LI

IPC: H01L21/033 ,  H01L21/02 ,  H01L21/027 ,  H01L21/311 ,  H01L21/3205 ,  H01L21/3213

CPC classification number: H01L21/0337 ,  H01L21/0217 ,  H01L21/02274 ,  H01L21/0273 ,  H01L21/0332 ,  H01L21/31116 ,  H01L21/31138 ,  H01L21/31144 ,  H01L21/32055 ,  H01L21/32137 ,  H01L21/32139

Abstract: A new variable selective etching technology for thick SOI devices. An SOI material is etched by the following steps: (1) providing an SOI wafer; (2) depositing a composite hard mask with a variable selection ratio to replace a traditional hard mask with an invariable selection ratio; (3) applying a photoresist; (4) mask making, namely defining a to-be-etched region by using a photoetching plate; (5) etching the photoresist in the defined region; (6) etching the composite hard mask; (7) removing the photoresist; (8) etching top silicon by using a second etching method at a first selection ratio; and (9) etching a buried oxide layer by using a third etching method at a second selection ratio. The new variable selective etching technology avoids the damage to a side wall of a deep trench when the buried oxide layer is etched, and does not need to use an excessive thick hard mask.