ENHANCED TUNNELING CHARACTERISTICS OF PECVD SILICON-RICH-OXIDE (SRO) FOR THE APPLICATION IN LOW-VOLTAGE FLASH EEPROM

High tunneling efficiency is indispensable for the application of low voltage flash EEPROM. In this study the enhanced tunneling characteris tics of the thin silicon-Rich-Oxide (SRO) films deposited using Plasma Enhanced Chemical Vapor Deposition (PECVD) as a tunneling injector wa s first reported. By optimizing the reactant gas ratios of [N2O]/[SiH4 ] during SRO deposition, the tunneling voltage of flash EEPROM can be 1/3 lower than that without PECVD SRO films. The significant tunneling efficiency is found to be caused by the micro Si-islands in SRO films . Micro Si-islands in SRO films enhance the electrical field of the tu nneling oxide in flash EEPROM. A modified WKB tunneling approximation have been successfully applied to model the SRO tunneling characterist ics. The field enhancement factor of SRO is also found to depend on th e oxide electrical field, and is proportion to the inverse of oxide el ectrical field.