A novel BE-SONOS NAND Flash using non-cut trapping layer with superb reliability

This work presents superb chip-level reliability of a BE-SONOS charge trapping NAND fabricated in both 75nm and 38nm half-pitches. Without any error correction (ECC) >;100K P/E cycling endurance for SLC and >;3K endurance for MLC are obtained using a novel non-cut SiN trapping layer. Key process integration strategies are discussed, including barrier and trapping layer engineering, p-well and junction doping optimization, gate-etching profile, and SSL/GSL processing. In addition to the overall good performance in programming/erasing and reliability, the non-cut SiN also demonstrated charge retention without any lateral spread - contrary to common misperception of charge migration in SiN. We believe this is the first time the reliability and performance of a charge trapping NAND chip are demonstrated to match or surpass those for FG NAND.