Laser thermal annealing of silicon nitride for increased density and etch selectivity

摘要

The density of a deposited silicon nitride layer is increased by laser thermal annealing in N2, thereby increasing etch selectivity with respect to an overlying oxide and, hence, avoiding damage to underlying silicide layers and gates. Embodiments include laser thermal annealing a silicon nitride layer deposited as an etch stop layer, e.g., in fabricating EEPROMs, to increase its density by up to about 8%, thereby increasing its etch selectivity with respect to an overlying BPSG layer to about {fraction (1/12 to about {fraction (1/14.