| 摘要 |
A process flow for forming a sacrificial collar (132) within a deep trench (113) of a semiconductor memory cell. A nitride liner layer (120) is deposited over a substrate (111). A thin polysilicon layer (122) is deposited over the nitride liner layer (120), and an oxide layer (124) is formed. A resist (116) is deposited within the trenches (113) and etched back. The top portion of the oxide layer (124) is removed, and the resist (116) is removed from the trenches (113). The wafer (100) is exposed to a nitridation process to form a nitride layer (128) over exposed portions of the polysilicon layer (122). The oxide layer (124) and polysilicon layer (124) are removed from the bottom of the trenches. (113). The nitride liner layer (120) is removed from the bottom of the trenches (113). The polysilicon layer (122) is removed from the top of the trenches (113) to leave a sacrificial collar (132) in the top of the trenches 113 formed by nitride liner layer (120).
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