The metal-nitride-oxide-silicon (MNOS) transistor—Characteristics and applications

Recent advances in silicon nitride deposition techniques have led to the emergence of the metal-nitride-oxide-silicon (MNOS) integrated circuit technology as an alternative and supplement to the existing MOS technology. Applications of MNOS field-effect transistors have been proposed for both logic circuits (as an alternative to MOS transistors) and nonvolatile memory arrays This paper reviews the characteristics and applications of MNOS transistors. It presents a unified approach to the characterization of both stable and variable turn-on voltage MNOS transistors. The analysis is based on an extensive investigation of charge transport and storage in MNOS structures. The different modes of transistor operation are described and analyzed in terms of the physical parameters of the two-layer dielectric structure. Understanding of the physical mechanisms underlying transistor operation is applied to the optimization of transistor structure and performance for different digital integrated circuit applications. The feasibility of these applications is demonstrated by fabrication of a nonvolatile semiconductor storage array and a nonvolatile flip-flop.