Patent ID: 7259984

Claim:
A multibit storage cell, comprising: a semiconductor substrate having source and drain regions separated by a channel region; an insulator material formed on said substrate and having a plurality of metal nanocrystals embedded therein, said metal nanocrystals including a first portion forming a first storage element located in the region of a source side junction with said channel and a second portion forming a second storage element located in the region of a drain side junction with said channel; a gate electrode on said insulator material; a control layer formed in said insulator material between said gate electrode and said metal nanocrystals; a tunnel layer formed between said metal nanocrystals and said substrate; and bias voltages connected to said source and drain regions to produce asymmetric charging of said nanocrystals, wherein said metal nanocrystals are formed from a metal that is selected to have a work function value which affects transport of charge through said insulating material such that a first, low potential barrier is formed across said tunnel oxide during writing to said storage elements, and a second, higher potential barrier is formed across said tunnel oxide during retention of charge in said storage elements.