A novel SONOS structure of SiO/sub 2//SiN/Al/sub 2/O/sub 3/ with TaN metal gate for multi-giga bit flash memories

A novel SONOS structure of SiO/sub 2//SiN/Al/sub 2/O/sub 3/ (SANOS) with TaN metal gate is for the first time proposed for the next generation non-volatile memory technology. When TaN metal gate is applied for the SANOS instead of commonly used n+ poly-Si, the unwanted backward Fowler-Nordheim tunneling current of electrons through the top oxide is significantly suppressed owing to its higher work function and better compatibility with high k dielectrics. As a result, the program/erase speed is significantly improved and the saturation level of erase V/sub TH/ can be obtained to be a negative voltage of -3.5V.