A highly punchthrough-immune operation method for an ultra-short-channel hot-carrier-injection type non-volatile memory cell

A novel bias scheme is proposed for non-volatile memory cells arranged in a virtual-ground array that utilizes hot-carrier injections for program and erase operations. By taking two adjacent cells on the same wordline as a unit, and letting the commonly shared n+ region being floating during program and erase, punchthrough immunity is greatly improved. Program/erase speed, endurance, and retention characteristics are comparable to conventional operations. NBit cell is projected to be workable at sub-40 nm node by such scheme.