Investigation of reliability degradation of ultra-thin gate oxides irradiated under electron-beam lithography conditions

Abstract

The effect of Electron-beam irradiation on the reliability of ultra-thin gate oxide has been studied under typical Electron-beam lithography conditions. A large increase of low-field excess leakage current was observed on irradiated oxides, which was found to be very similar to the electrical stress-induced leakage currents. An experimental relationship between the total Electron-beam dosage and the equivalent charge fluence, which induces the same amount of current degradation, has been established for different oxide thickness. This allows for easier prediction of radiation damage. It has also been found that Electron-beam irradiation generates much larger amount of oxide bulk traps but generates a comparable amount of interface states, compared to electrical stress. Quasi-breakdown characteristics show that Electron-beam irradiation up to a dose of 500 μC/cm2 does not accelerate quasi-breakdown of ultra-thin gate oxide. ©2000 The Japan Society of Applied Physics.