发明授权
US6117733A Poly tip formation and self-align source process for split-gate flash
cell
有权
分离栅闪光单元的多尖端形成和自对准源工艺
- 专利标题: Poly tip formation and self-align source process for split-gate flash cell
- 专利标题(中): 分离栅闪光单元的多尖端形成和自对准源工艺
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申请号: US193670申请日: 1998-11-17
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公开(公告)号: US6117733A公开(公告)日: 2000-09-12
- 发明人: Hung-Cheng Sung , Di-Son Kuo , Chia-Ta Hsieh , Yai-Fen Lin
- 申请人: Hung-Cheng Sung , Di-Son Kuo , Chia-Ta Hsieh , Yai-Fen Lin
- 申请人地址: TWX Hsin-Chu
- 专利权人: Taiwan Semiconductor Manufacturing Company
- 当前专利权人: Taiwan Semiconductor Manufacturing Company
- 当前专利权人地址: TWX Hsin-Chu
- 主分类号: H01L21/8247
- IPC分类号: H01L21/8247 ; H01L29/423 ; H01L21/336 ; H01L29/72 ; H01L31/00
摘要:
A novel method of forming a first polysilicon gate tip (poly tip) for enhanced F-N tunneling in split-gate flash memory cells is disclosed. The poly tip is further enhanced by forming a notch in two different ways in a nitride layer overlying the first polysilicon layer. In one embodiment, the notch is formed after wet oxidizing the sidewalls of the underlying first polysilicon layer, thus at the same time forming a poly tip which is exposed upwardly but covered by polyoxide on the side. In another embodiment, the notch is formed prior to the oxidation of the exposed regions of the first polysilicon layer, such as the sidewalls, so that during the subsequent oxidation, not only the sidewalls but also the exposed portions of the polysilicon in the notch region are also oxidized. Because the oxidation of the polysilicon advances in a non-uniform manner with very little at the polysilicon/nitride interface and to a larger rate elsewhere, a thin and robust polysilicon tip is formed which is at the same time covered by oval-shaped poly-oxide on all sides. A method of forming a self-aligned source (SAS) line is also disclosed in conjunction with the forming of the polytip. Hence the combination of an enhanced poly tip with a self-aligned source provides a faster split-gate flash memory device.
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