TEMPERATURE-DEPENDENCE OF TRANSPORT AND TRAPPING PROPERTIES OF OXIDE-NITRIDE-OXIDE DIELECTRIC FILMS

The transport and trapping properties of ONO films are investigated at low and high electric fields in the temperature range 25-400 degrees C. The experimental results clearly demonstrate that Fowler-Nordheim e mission is the main mechanism of current leakage at high field, while a thermally activated quasi-ohmic conduction process is responsible fo r the leakage currents at low field, independently of the bottom oxide thickness and gate polarization. It is also found that the shift and modification of the I(V) characteristics after several measurement pas ses can be attributed to electron trapping which occurs during the mea surement. Modeling of the It V) characteristics is carried out after a ccounting for the charge trapping during the measurement with quasi-lo garithmic trapping kinetics. The impact of temperature on the leakage current and on the apparent Fowler-Nordheim exponential coefficient ar e also simulated satisfactorily using a complete F-N emission model at high field and a thermally activated ohmic conduction mechanism at lo w field. (C) 1997 Elsevier Science Ltd.