Local oxidation of silicon planarization for polysilicon layers under thin film structures

In accordance with the teachings described herein, a method for fabricating a patterned polysilicon layer having a planar surface may include the steps of: depositing a polysilicon film above a substrate material; depositing an oxide-resistant mask over the polysilicon film; patterning and etching the oxide-resistant mask to form a patterned mask layer over the polysilicon film, such that the polysilicon film includes masked and unmasked portions; etching the unmasked portions of the polysilicon film for a first amount of time; oxidizing the etched polysilicon film for a second amount of time to form an oxide layer that defines the patterned polysilicon layer; and removing the patterned mask layer; wherein the first and second amounts of time are selected such that the oxide layer and the patterned polysilicon layer have about the same thickness and form a planar surface.