A Comprehensive Characterization Method for Lateral Profiling of Interface Traps and Trapped Charges in P-SONOS Cell Devices

Abstract

A comprehensive characterization method has been developed in this paper for reliable lateral profiling of the interface traps (Delta N-it), localized charges (Delta N-ot), and trapped holes (Delta N-hole) in P-SONOS cell devices. Charge pumping current (I-CP) measurement can be used to probe Delta N-it and Delta N-ot from the increase of maximum I-CP (I-CP,I- max) and the shift of I-CP curve along the base level voltage (V-b). When increasing the program and erase (P/E) cycles, the negative threshold voltage (V-T) shift at both program and erase states suggests the generation of Delta N-hole. The evolution of Delta N-it, Delta N-ot, and Delta N-hole during P/E cycling can consistently explain the nonmonotonic variations of gate induced drain leakage current (I-GIDL) and substrate current (I-SUB) as well as dramatic differences between the source and drain. The lateral migration of Delta N-ot caused by extending P/E cycles may lead to the failure of two-bit operation in SONOS cell devices. The larger V-T shift and subthreshold swing, smaller read current, and lower transconductance may degrade the endurance and retention of P-SONOS when applied in Flash memory.