The effect of surface roughness of Si/sub 3/N/sub 4/ films on TDDB characteristics of ONO films

Abstract

The surface roughness of Si/sub 3/N/sub 4/ films was found to become higher and to cause degradation of time-dependent dielectric breakdown (TDDB) characteristics of ONO films with increasing deposition temperature of Si/sub 3/N/sub 4/ films. A local thinning of ONO films, evaluated from the TDDB characteristics, agreed with the surface roughness measured by the atomic force microscope (AFM) and the cross-sectional transmission electron microscope. The dependence of the time to breakdown of ONO films on the deposition temperature was interpreted by electric field intensification due to the surface roughness of Si/sub 3/N/sub 4/ films.<>