Abstract
The comparatively high conductivity of thermal 
layers on polycrystalline silicon has been attributed by previous workers to local enhancement of the oxide electric field due to interface roughness and/or 
thickness nonuniformities. In this paper, we correlate the measured effective barrier height for Fowler‐Nordheim tunneling, 
, with the rms surface roughness as measured by the surface plasmon technique. Our results show that, for thermal 
on untextured polysilicon, there is a decrease in 
from approximately 2.8 to 0.8 eV as oxide thickness is increased from 16.7 to 165 nm. This decrease in 
is directly attributable to a corresponding increase in rms interface roughness from approximately 0.9 to 1.6 nm due to oxidation‐induced roughness caused by locally nonuniform polysilicon oxidation rate. Similar behavior is observed for relatively thin oxides (approximately 25 nm thick) on textured polysilicon. Furthermore, the roughness values obtained for the upper and lower oxide/polysilicon interfaces are found to be in agreement with the observed conduction properties that are shown to be highly asymmetric for thermal 
on untextured polysilicon but essentially polarity independent for oxides on textured polysilicon.