Methods of forming electrically isolated active region pedestals using

Abstract

Methods of forming electrically isolated active regions in semiconductor substrates include the steps of forming a plurality of trenches in a face of a semiconductor substrate to define an active region pedestal between first and second dummy region pedestals and then forming an electrically insulating layer on the active region and dummy region pedestals and in the trenches disposed therebetween. A mask is then patterned to expose a portion of the electrically insulating layer on the active region pedestal and then the exposed portion of the electrically insulating layer is etched so that a thickness of the electrically insulating layer on the active region pedestal is less than a thickness of the electrically insulating layer on the first and second dummy region pedestals. A step is then performed to planarize the electrically insulating layer to selectively expose the active region pedestal but not the first and second dummy region pedestals. This planarizing step also results in the formation of a uniform surface profile at the edges of the active region pedestal.