INVESTIGATION OF CHARGE TRAPPING CENTERS IN SILICON-NITRIDE FILMS WITH A LASER-MICROWAVE PHOTOCONDUCTIVE METHOD

A new method using a laser microwave photoconductance (LMPC) technology for the investigation of charge trapping centers in silicon nitride films was demonstrated by studying the ultraviolet (UV) irradiation effect upon minority-carrier recombination lifetime of silicon with the film. The lifetime is found dependent on the film thickness. UV irradiation dramatically decreases the lifetime for the samples with the thick film. The decreased lifetime is transient and recovers to the initial value after long time storage at room temperature. The recovery accelerates with increasing temperature. The lifetime behavior is correlated with the charge states of K centers in the nitride film. It is then shown that the electronic structure of the charge trapping centers can be studied by an investigation of the lifetime recovery process after UV irradiation with temperature controlled LMPC measurements.