Semiconductor device evaluation method, method of controlling the

Abstract

An electric field changing in the form of a ramp waveform with the passage of time is applied to an oxide layer, and the electric current densities applied to the oxide layer at measuring points of time are measured. The electric current densities applied until the oxide layer is broken down, are integrated with respect to time, thus obtaining a total electric charge amount Qbd used up to the breakdown of the oxide layer. The total electric charge amount Qbd is divided by each of the electric current densities at the measuring points of time, thus obtaining each of the estimated values of oxide layer lifetime at the time when it is supposed that each of the electric current densities at the points of time was constantly applied. Using the field intensities and the lifetime estimated values at the common measuring points of time, there is determined a regression line in which the oxide layer lifetime estimated values are expressed in the form of a function of the field intensities. Based on the regression line, a field acceleration coefficient is determined and the oxide layer lifetime at an optional field intensity is estimated.