Method of structuring layers with a polysilicon layer and an overlying metal or metal silicide layer using a three step etching process with fluorine, chlorine, bromine containing gases

Abstract

Doped polysilicon layers and layered polysilicon structures are produced, and the layers and layered structures are structured. The doping is distinguished by the fact that the doping compound is added as a process gas during the chemical vapor deposition of the polysilicon to define the doping profile. The feed of dopant to the process gas is stopped toward the end of the vapor deposition, with the result that a boundary layer of undoped silicon is deposited. As a result, a favorable surface quality and better adhesion to a neighboring layer is obtained. The structuring process comprises an at least three-step etching process in which a fluorine containing gas is used for etching in a first step, a chlorine-containing gas is used for etching in a second step and a bromine-containing, gas is used for etching in a third step. The invention also encompasses wafers and semiconductor chips produced with the novel doping and/or structuring method.

Dependencies are inferred from the claim text.