Experimental determination of the frequency factor of thermal annealing processes in metal-oxide-semiconductor gate-oxide structures

Abstract

Radiation-induced trapped charge annealing processes in the gate and field oxides of metal-oxide-semiconductor field-effect transistors are thermally activated. The activation energy and the frequency factor are related to the relaxation time constant by an Arrhenius law. A simple measurement of the relaxation time constant defines the activation energy, frequency factor (E, ν) pair. Choosing arbitrarily a "realistic" frequency factor corresponds to determining a characteristic energy, on which depends any subsequent annealing prediction. A controversy exists about the appropriate value of ν for silicon dioxide, with published values ranging from 1 × 107 to 1 × 1014 s-1. In this paper, a new method is presented that yields values for both frequency factor and activation energy. This method leads to an unexpectedly low (but consistent) value of ν (about 1 × 107 s-1) when applied to three different devices, obtained from three different manufacturers. The experimental procedure and the results for all three cases are presented and discussed. © 1997 American Institute of Physics.