Process for forming sloped topography contact areas between polycrystalline silicon and single-crystal silicon

Claim 1

A process for forming a sloped topography buried contact area between a polycrystalline silicon conductive layer and a single crystal silicon substrate through openings in insulation material overlying said substrate without creation of deep crevices in said contact area, comprising: forming a polycrystalline silicon layer over at least a portion of said insulating material and over the single crystal silicon substrate exposed by said openings in said insulation material, said polycrystalline silicon layer including a contiguous tip of single crystal silicon material where said polycrystalline silicon layer contacts said exposed single crystal silicon substrate; and defining said polycrystalline layer by masking those areas of said polycrystalline silicon layer to be retained and etching unwanted polycrystalline silicon areas including said contact area with an orientation selective etch which etches polycrystalline silicon preferentially to single crystal silicon whereby unwanted polycrystalline silicon is removed while said contiguous tip of single crystal silicon material inhibits creation of deep crevices in said contact area.