Method for local oxidation of silicon (LOCOS) field isolation

摘要

A method for forming field oxide comprises the steps of forming a pad oxide layer over a semiconductor substrate, then forming a silicon layer over the pad oxide layer. A patterned mask is formed over the silicon layer and the silicon layer is etched to form openings in the silicon layer. Next, a blanket nitride layer is formed over the silicon and within the openings, and the nitride layer is then planarized to remove the nitride which overlies the silicon which leaves the nitride in the openings. Subsequent to the step of planarizing the nitride, the silicon layer is removed thereby forming openings in the nitride layer. The substrate is oxidized at the openings in the nitride layer to form field oxide from the substrate.