Capacitance-voltage characteristics measured through pulse technique on high-k dielectric MOS devices

Capacitance-voltage (CV) characteristics were investigated for MOS devices with ZrO₂ and HfO₂ high-k dielectrics using pulse technique and LCR meter. Opposite relative positions of the forward and reverse traces were observed for the CV curves extracted from the two techniques. This unusual phenomenon was believed to be caused by the interface dipoles formed at high-k/SiO_x interface, since it was difficult to be convincingly explained by trapping/de-trapping of charges. The effect of interface dipoles on CV characteristics was found to be sensitive to the voltage ramp rate. In addition, a hump in the inversion region for the forward trace in pulse technique was detected. This may be due to an additional current due to the PN junction formed between the substrate and inversion layer via the pulse technique process.