Investigation of programming charge distribution in nonoverlapped implantation nMOSFETs

Abstract

Novel gate-to-drain nonoverlapped-implantation (NOI) nMOSFETs have been developed as potential multibit-per-cell nonvolatile-memory (NVM) devices. The lateral charge distribution of the NOI NVM device programmed by channel hot electron injection is investigated by charge-pumping (CP) techniques with presumed interface trap distributions. For the first time, the CP results have revealed the lateral charge distribution and trapping density at the NOI's programmed state. The maximum trapping charge density locates near its drain junction. The charge distribution is estimated about 90 nm in length and spread widely over the NOI region. Two-dimensional simulators with charge bars using the same charge trapping distribution confirm the experimental results by fitting their I-DS - V-G curves.