In one embodiment a non-volatile memory device having improved reliability is formed by oxidizing a first portion of a semiconductor substrate (12) to form a first silicon dioxide layer (14). The first silicon dioxide layer (14) is then annealed and second portion of the silicon substrate, underlying the annealed silicon dioxide layer (16), is then oxidized to form a second silicon dioxide layer (18). The annealed silicon dioxide layer (16) and the second silicon dioxide layer (18) form a pre-oxide layer (20). The pre-oxide layer (20) is then nitrided to form a nitrided oxide dielectric layer (22). A floating gate is then formed overlying the nitrided oxide dielectric layer (22), which serves as the tunnel oxide for the device. Tunnel oxides formed with the inventive process are less susceptible to stress-induced leakage, and therefore, devices with improved data retention and endurance may be fabricated.