Non-contact C-V measurements of ultra thin dielectrics

In this paper, we present a non-contact C-V technique for ultra-thin dielectrics on silicon. The technique uses incremental corona charging of dielectric and a measurement of the surface potential with a vibrating capacitive electrode. A differential quasistatic C-V curve is generated using time-resolved measurements. The technique incorporates transconductance corrections that enable corresponding ultra-low electrical oxide thickness (EOT) determination down to the sub-nanometer range. It also provides a means for monitoring the flat band voltage, V FB , the interface trap spectrum,D IT , and the total dielectric charge, Q TOT . Thistechnique is seen as a replacement for not only MOS C-Vmeasurements but also for mercury-probe C-V. In addition, EOTmeasurement by the corona C-V has a major advantage over opticalthickness methods because it is not affected by water adsorptionand molecular airborne contamination, MAC. These effects havebeen a problem for optical metrology of ultra-thin dielectrics.