On-Chip Recovery Operation for Self-Aligned Nitride Logic Non-Volatile Memory Cells in High-K Metal Gate CMOS Technology

A new on-chip recovery operation is proposed in the self-aligned nitride (SAN) cell. Merged nitride spacer is sandwiched between high-k metal gate stacks in nano-meter CMOS process. The scaled gate length enables the SAN cell be erased by band-to-band hot hole. For multiple-time-programming operation, two effective recovery methods are proposed to recover on/off window after cycling stress. Both ac and dc methods are applied to eliminate deep-trapped charges via electrical self-heating. Experimental data demonstrates dc recovery methods that provide nearly full damage anneal capability and, in turn, effectively extend SAN cell's endurance level.