The effect of Shallow Trench Isolation improvement on program disturb response in 20 nm NAND flash technology

In this paper, the effect of Shallow Trench Isolation (STI) degradation on program disturb is studied. It is reported that trench isolation is compromised with non-uniformity in trench depth leading to increased boost loss through field isolation leakage. This degradation in boost loss further leads to elevated program disturb fails. Further investigation identified three factors namely-STI depth Imbalance, channel enhancement implant and STI etch process with improved cross wafer profile, which have been optimized to successfully alleviate Program Disturb fails.