Automatic, wafer-level, low frequency noise measurements for the interface slow trap density evaluation

A system for automatic, wafer-level, low frequency current fluctuations measurements on semi-conductor devices is presented. The system uses a novel, programmable current amplifier, which enables computer-controlled device biasing for static and noise characteristics measurements at the currents varied by up to 6 orders of magnitude, with a corresponding programmable gain variation. Such current dynamics is needed for extraction of device parameters such as the density of slow traps at the Si/dielectric interface in devices. The system´s application for that purpose is illustrated using the low frequency noise, LFN, results obtained on nMOSFETs with HfO₂ gate dielectrics. A novel procedure for the amplifier´s calibration by thermal sources is also presented. The system is shown to have a capacity for repetitive LFN device testing in industrial environment.