Electrical characterization of ONO triple dielectric in SONOS nonvolatile memory devices

Polysilicon-oxide-nitride-oxide-silicon nonvolatile memory devices are char acterized by a high concentration of traps in the silicon nitride layer wit h a well-defined trapping distance, corresponding to the tunnel oxide thick ness. A "breakpoint" is observed at a particular frequency with an inverse equivalent to the trap-to-trap tunneling time constant by variable frequenc y charge pumping technique. from which the tunnel oxide thickness can be de cided. By examining the charge transport and trapping properties of nitride films utilizing charge separation technique. an experimental method to ext ract the silicon nitride storage layer thickness has been developed. Excell ent agreement is obtained between the ellipsometry results and extracted va lues. (C) 1001 Elsevier Science Ltd. All rights reserved.