CSL-NOR형 SONOS 플래시 메모리의 멀티비트 적용에 관한 연구

Abstract

NOR type flash 32 x 32 array are fabricated by using the typical 0.35 ㎛ CMOS process. The structure of array is the NOR type with common source line. In this paper, optimized program and erase voltage conditions are presented to realize multi-bit per cell at the CSL-NOR array. These are considered selectivity of selected bit and disturbances of unselected bits. Retention characteristics of locally trapped-charges in the nitride layer are investigated. The lateral diffusion and vertical detrapping to the tunneling oxide of locally trapped charges as a function of retention time are investigated by using the charge pumping method. The results are directly shown by change of the trapped-charges quantities.