Method of fabricating a kink-effect-free shallow trench isolations

Abstract

A method of fabricating kink-effect-free shallow trench isolations is presented in this invention. First, a layer of silicon oxide and a layer of polysilican are sequentially deposited on a substrate, and then shallow trenches are formed, next thermal oxidation is performed to grow a passivation oxide layer on the exposed silicon, and then, a dielectric layer is formed to fill into the shallow trench. Finally, the dielectric layer on the active area is removed by using chemical mechanical polishing and the polysilicon layer provides for the etching end point. The level of shallow trench is higher than the level of active area as soon as stop polishing, because the polysilicon layer is polished faster than dielectric layer. It provides the passivation oxide on the sidewall of shallow trench to form spacers of the active area after removing the polysilicon of active area. It can provide a perfect shallow trench after an oxidation and etching process to avoid the kink effect.