80 Angstrom oxynitride dielectrics grown by rapid thermal processing in N2O ambients have been evaluated in terms of thickness uniformity and electrical properties. Three types of growth processes are compared in this work : (i) one-step growth in pure N2O ambients, (ii) one-step growth in mixed O-2/N2O ambients, and (iii) a two-step process with an initial growth in O-2 followed by growth in N2O. Excellent cross-wafer thickness uniformity has been achieved, notably by the two-step process. At a given temperature, thickness uniformity deteriorates with increasing levels of nitridation. However the electrical characteristics (charge-to-breakdown and charge trapping) are enhanced for the oxynitrides when compared to conventional thin oxides, and these improve with increasing levels of nitridation. Higher oxynitride growth temperatures were seen to improve both the thickness uniformity and the electrical properties. Electrically erasable programmable read-only memory cells fabricated with an oxynitride tunnel dielectric exhibit significantly less window narrowing during write-erase cycling than reference cells with a standard tunnel oxide.