Low-Frequency Noise Characteristics in SONOS Flash Memory With Vertically Stacked Nanowire FETs

Low-frequency (LF) noise in a vertically stacked nanowire (VS-NW) memory device, which is based on the silicon–oxide–nitride–oxide–silicon (SONOS) configuration is characterized in two different operational modes, an inversion-mode and a junctionless-mode (JM). The LF noise showed 1/ $f$ –shape behavior regardless of the operational mode and followed the carrier number fluctuation model. With regard to the device-to-device variation and quality degradation of the LF noise after iterative program/erase operations, the five-story JM SONOS memory showed comparatively high immunity arising from its inherent bulk conduction and no-junction feature. Despite the harsh fabrication condition used to construct five-story VS-NW, even the five-story JM SONOS memory exhibited LF noise characteristics comparable to those of one-story JM SONOS memory. Thus, the five-story JM SONOS memory is attractive due to its high-performance capabilities and good scalability.