| 摘要 |
The method includes the steps of etching a silicon substrate (11) to form a pair of trenches into the substrate (11) to implant impurity ions into the active region between the trenches to form a P- region (12) and a P+ region (13) as a double well structure, etching the active region to form a second trench thereinto to implant impurity ions on the well region between the first and second trenches to form source and drain regions as a LDD structure, forming an oxide film into the first and second trenches to deposit a polysilicon layer into the second trench to form a gate, and forming contact holes on the source, drain and gate portions, thereby using the trench structure and twin well process to improve the step coverage and latch-up at the side of bulk.
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