Programmable non-volatile memory with low off current

Abstract

In one disclosed embodiment, a non-volatile memory cell is constructed using a floating gate transistor with a channel that includes a buried channel region interposed between two surface channel regions under a floating gate. The surface channel regions are formed using angled lightly-doped drain implantation at locations in the substrate so that a first surface channel region is located under a first end of the floating gate and a second surface channel region is located under a second end of the floating gate. In one embodiment, the floating gate transistor is a PMOS transistor, with the channel being formed in an n-well formed in a p-type substrate, with the buried channel region being formed using a Vtp implant, and with the surface channel regions being formed using angled NLDD implants. The surface channel regions increase the energy barrier along the channel and reduce off state current of the memory cell.