High performance and reliable submicron EPROM technologies to realize 4Mb density and fast operation speed have been developed. The main key process technologies are (a) thin reliable inter-poly dielectrics, (b) SAC (Self Aligned Contact) using RTA (Rapid Thermal Annealing), and (c) low resistance polycide gate. The device uses 0.8µm N-well CMOS technology. Masked MLDD(Moderately Lightly Doped Drain) NMOS transistors are used in peripheral circuits. Submicron EPROM cell offers sufficiently fast write speed and soft-write endurance.