RTS Noise Analysis in Fin-type Silicon-Oxide-High-k-Oxide-Silicon Flash Memory

This paper discusses the Random Telegraph Signal (RTS) noise in Fin-type Silicon-Oxide-High-k-Oxide-Silicon (SOHOS) and Fin-type Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) devices to find out the trap properties of trapping layer. The vertical location of a trap (x(T)) in SOHOS and SONOS devices is extracted to be 4.61 nm and 4.36 nm, respectively, which means that considering the tunneling oxide thickness of both devices is 3 nm, the RTS method can be used to characterize the trapping layer properties in SOHOS/SONOS structure. The measurement results show that Delta I-D/I-D of SONOS device is larger than that of SOHOS device which has inferior data retention characteristics. It reveals that a percolation caused by nitride trapped charges which is not redistributed in gate oxide increases the RTS noise. In SOHOS, however, the trapped charges can be easily redistributed degrading the data retention characteristics. This result is in agreement with previous results that data retention properties is deteriorated due to the presence of conduction paths in HfO2 used as trapping layer.