Electrical methods for estimating the correlation length of insulator thickness fluctuations in MIS tunnel structures

The possibilities of experimental extraction of the correlation length of insulator thickness fluctuations from the data of electrical measurements on thin metal-insulator-semiconductor (MIS) structures are discussed. The procedure of statistical treatment of currents flowing in a random selection of MIS tunnel diodes is developed enabling the estimation of such a length. Another proposed technique is based on the quantitative analysis of soft-breakdown-related current jumps down occurring under high-voltage stress. The novel methods were tested using Al/SiO2/Si structures and shown to yield the value of correlation length close to that given by a straightforward “covariant” method applied to the thickness profiles of the same oxide films.