| 摘要 |
PURPOSE: To form a deeply buried high node region by forming an insulation layer on a silicon substrate, forming a polysilicon layer of specified thickness on the insulation layer and then making a trench through respective layers thereby exposing the surface region of the silicon substrate. CONSTITUTION: An alternate combination of polysilicon layers 10a, 10b, 10c and silicide layers 12a, 12b having thickness of (1.0-1.25)×SQRT (WS/WD)μm or less per 1MeV increment at implantation energy terminates at a bottom polysilicon layer 10c isolated from a substrate 14 by a silicon dioxide layer 16. WS is atomic weight of silicon, WD is atomic weight of dopant and SQRT is the root of bracketed parameters. Subsequently, the polysilicon layers 10a, 10b, 10c are etched down to the underlying silicide layers 12a, 12b and the oxide layer 16 to strip off the oxide layer 16 and the oxide on the side wall of the trench 11 thus exposing a desired region 24 on the silicon substrate 14.
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