Thermally stimulated exoclectron emission has been applied for high-resolution depth profiling of traps in amorphous SiO2/Si3N4/SiO2 (ONO) dielectric stacks used in silicon-oxide-nitride-oxide-silicon (SONOS) memory devices. It is shown that maximum density of traps responsible for charge storage in ONO structures is at the interface between top silicon oxide and silicon nitride in ONO. (C) 2004 Elsevier B.V. All rights reserved.