Patent ID: 6124206
Filing Date: 2000-09-26
Classification: H01L

Abstract:
A method for providing a substantially planar pad stack after trench formation and filling comprising the steps of:providing a substrate;forming a pad stack on the substrate;forming a hard mask above the pad stack, wherein the hard mask comprises an etch stop layer between first and second hard mask layers;etching through the hard mask and the pad stack to form the trenches in the substrate;filling the trenches with polysilicon;removing the first hard mask layer selective to the polysilicon and the etch stop layer such that polysilicon protrusions remain above the etch stop layer;polishing the polysilicon protrusions to provide a substantially planar surface on the etch stop layer;removing the etch stop layer and the second hard mask layer permitting the polysilicon protrusions to extend above the pad stack layer; andpolishing the polysilicon protrusions to provide a substantially planar surface on the pad stack layer.