Method of forming a self-aligned shallow trench isolation

摘要

A method for fabricating a semiconductor device, for example a non-volatile memory device having a stacked gate (memory cell) consisting of a floating gate, a control gate deposited over the floating gate, and a dielectric interlayer interposed between them, comprises the steps of sequentially depositing: a tunnel oxide layer, a first polysilicon layer for the floating gate, and a nitride layer over a semiconductor substrate, sequentially etching the nitride layer, first polysilicon layer, and semiconductor substrate to form a trench, depositing an oxide layer over the substrate to fill the trench, removing the oxide layer to the level of the nitride layer to attain a field region of the trench isolation, removing the nitride layer, subjecting the field region to a wet-chemical treatment, and depositing a second polysilicon layer for the floating gate over the substrate.