Characteristics of Sub-50 nm NAND Flash Devices with Various Self-Aligned Shallow Trench Isolation Depths

The program efficiency and endurance characteristics of sub-50nm NAND flash devices with various self-aligned shallow trench isolation (SA-STI) depths are investigated. Although a large SA-STI depth improves the neighboring floating gate coupling issue and gate coupling ratio, a low program efficiency is also introduced. In addition, lower endurance characteristics are observed in the device with a large SA-STI depth than in the device with a small SA-STI depth. The mechanisms underlying such unfavorable results are discussed on the basis of experimental data and technology computer-aided design simulations. (C) 2013 The Japan Society of Applied Physics