Characterizing damage to ONO dielectrics induced during programming SONOS/NROM~(TM) non-volatile semiconductor memory (NVSM) devices

摘要

We present experimental results on scaled silicon-oxide-nitride-oxide-silicon (SONOS/NROM~(TM)) transistors using a variety of programming mechanisms. These devices store holes and electrons in traps in a nitride layer in the gate dielectric. Programming is achieved with a variety of mechanisms: modified Fowler-Nordheim (MFN) tunneling, channel hot electron injection (HEI), and hot hole injection (HHI). All measurements are performed on transistors with gate dielectrics composed of a tunneling oxide (X_(OT)), silicon-nitride charge-storage layer (X_N), and a blocking oxide (X_(OB)) of 4, 4.2, and 4.4 nm (NROM~(TM)) or 2, 7, and 4 nm (SONOS), respectively. Charge pumping measurements are employed to characterize the interface trap density of fresh devices and monitor the generation of new interface traps during write/erase operations. We study the damage to ONO dielectrics caused by write/erase cycling by comparing interface trap densities for SONOS/NROM~(TM) devices programmed using varying charge-injection mechanisms after 10~6 write/erase cycles for 10 year retention.