Integration of an ion implant hard mask structure into a process for fabricating high density memory cells

Abstract

A process for fabricating a memory cell in a two-bit EEPROM device, the process includes forming an ONO layer overlying a semiconductor substrate, depositing a hard mask overlying the ONO layer, and patterning the hard mask. Preferably, the hard mask includes a material selected from the group consisting of tungsten, titanium, titanium nitride, polysilicon, silicon, silicon nitride, silicon oxi-nitride, and silicon rich nitride. In one preferred embodiment, the process further includes implanting the semiconductor substrate with a p-type dopant at an angle substantially normal to the principal surface of the semiconductor substrate and annealing the semiconductor substrate upon implanting the semiconductor substrate with a p-type dopant. In one preferred embodiment, the process further includes implanting the semiconductor substrate with an n-type dopant.