Abstract: To address problems encountered during the fabrication of a nonvolatile memory cell, such as preventing top oxide loss, preventing contact between the nitride and the polysilicon, and reducing the problem of BD over-diffusion, various fabrication embodiments are used. In one approach, the top dielectric of an ONO structure is formed at the same time as the oxide covering the implanted regions. In another approach, another dielectric structure is formed on the implanted regions and on the top oxide of the charge storage structure. In yet another approach, a cleaning process following ion implantation is performed prior to forming the top oxide of the ONO structure. These approaches also apply to floating gate nonvolatile memories.