Abstract: A method for forming an IPO between two polysilicon layers that produces an oxide of superior uniformity and eliminates undercutting, stringer formation, fringe electric fields and plasma damage. The method modifies the prior art by using a densified TEOS mask to allow etching away of the substrate oxide and allow the selective etch of a subsequent non-densified TEOS layer. A high temperature thermal oxide (HTO) then covers the resulting formation. The thickness of the second TEOS layer can be controlled to prevent field fringing and the underlying HTO layer prevents undercutting and stringer formation.