Method for forming ETOX cell using self-aligned source etching process

摘要

A method for forming ETOX cells (Intel Type Flash EPROM Cell) using a self-aligned source etching process comprising the steps of depositing a silicon nitride layer up to a thickness of 100 Å to 700 Å, and then etching back the layer to form spacers. Thereafter, common source regions are defined using a photomask, and then the field oxide layer is etched using either a wet etching method or a dry etching method having a high selectivity ratio. The spacers are capable of protecting the oxide/nitride/oxide ONO layer against any damages during processing, thereby avoiding charge retention and reliability problems.