Improvement of the multi-level cell performance by a soft program method in flash memory devices

• Published in: Solid-state electronics 2014-04, Vol.94, p.86-90
• Main Authors: Park, Jong Kyung, Lee, Ki-Hong, Pyi, Seung Ho, Lee, Seok-Hee, Cho, Byung Jin
• Format: Article
• Language: English
• Subjects: Applied sciences; Blocking oxide; Compound structure devices; Data storage; Design. Technologies. Operation analysis. Testing; Electric potential; Electronics; Exact sciences and technology; Flash memory (computers); Instability; Integrated circuits; Integrated circuits by function (including memories and processors); Magnetic and optical mass memories; Memory devices; Oxides; Programming; Reliability; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Soft program; Storage and reproduction of information; TANOS; Voltage
• ISSN: 0038-1101; 1879-2405
• DOI: 10.1016/j.sse.2014.02.012

•A soft program method improves the multi-level cell performance.•The initial threshold-voltage instability can be improved by removing the shallowly trapped electrons.•Different high-κ blocking oxides have been investigated. A soft program method is proposed for charge-trap flash (CTF) memory devices. By adding a subsequent small positive gate pulse after main Fowler–Nordheim (FN) injection programming, early charge loss is greatly reduced. The multi-level cell performance as well as the initial flat-band voltage (VFB) instability can thereby be improved by removing the trapped electrons at the shallow traps in the blocking oxide layer. The proposed soft program method is a simple but very effective way to improve the fast retention property without changing the memory structure, especially for cases where the κ-value of the blocking oxide is high.