Method of increasing capacitance of polycrystalline silicon devices by

Abstract

A method of forming an electrically conductive polysilicon capacitor plate on a semiconductor substrate includes: a) providing a first layer of conductively doped polysilicon atop a semiconductor substrate to a first selected thickness; b) providing a thin layer of oxide atop the first polysilicon layer to a thickness of from about 2 Angstroms to about 30 Angstroms, the thin oxide layer having an outwardly exposed surface; and c) providing a second layer of conductively doped polysilicon having an outer exposed surface over the outwardly exposed thin oxide surface, the first polysilicon layer being electrically conductive with the second polysilicon layer through the thin layer of oxide, the second polysilicon layer having a second thickness from about 500 Angstroms to about 700 Angstroms, the thin oxide layer reducing silicon atom mobility during polysilicon deposition to induce roughness into the outer exposed polysilicon surface. Preferably, the polysilicon deposition, doping, oxide growth, and subsequent polysilicon deposition is all conducted in a single furnace sequence without removing the wafers from the furnace. Such facilitates throughput, and minimizes exposure of the wafer to handling which could lead to fatal damage. It is also contemplated that selected materials other than oxide would be usable to reduce the surface mobility, and thereby induce roughness. The invention also includes an electrically conductive polysilicon capacitor plate.