Title :
Analysis of detrap current due to oxide traps to improve flash memory retention
Author :
Yamada, Ren-ichi ; Mori, Yuki ; Okuyama, Yutaka ; Yugami, Jiro ; Nishimoto, Toshiaki ; Kume, Hitoshi
Author_Institution :
Central Res. Lab., Hitachi Ltd., Tokyo, Japan
Abstract :
To improve flash memory retention characteristics, we study detrap current due to oxide traps in metal-oxide-semiconductor structures (MOS capacitors and MOSFETs). We show that threshold voltage shift due to detrap current in flash memories can reach 0.6 V for 1 year. This value is detrimental for flash memory retention. Next, we analyze the two types of conduction mechanism of the detrap current, which are direct tunneling to the anode from deeper traps and thermally excited electron tunneling to the oxide conduction band from shallower traps. The deeper traps are generated by electron injection during Fowler-Nordheim stressing, while the shallower traps are generated by hole injection
Keywords :
MOS capacitors; MOSFET; electron traps; flash memories; hole traps; integrated circuit reliability; interface states; tunnelling; 1 year; Fowler-Nordheim stressing; MOS capacitors; MOSFET; Si-SiO2; conduction mechanism; constant current stress; constant voltage stress; deep traps; detrap current; direct tunneling; electron injection; flash memory retention characteristics; hole injection; metal-oxide-semiconductor structures; oxide conduction band; oxide traps; shallow traps; thermally excited electron tunneling; threshold voltage shift; Charge carrier processes; Electron emission; Electron traps; Flash memory; MOS capacitors; MOSFET circuits; Pulse measurements; Stress; Threshold voltage; Tunneling;
Conference_Titel :
Reliability Physics Symposium, 2000. Proceedings. 38th Annual 2000 IEEE International
Conference_Location :
San Jose, CA
Print_ISBN :
0-7803-5860-0
DOI :
10.1109/RELPHY.2000.843915
