A new method, called gate current Random Telegraph Noise (IG RTN), was developed to analyze the oxide quality and reliability of high-k gate dielectric MOSFETs. First, a single electron trapping/detrapping from process induced trap in nMOSFET was observed and the associated physical mechanism was proposed. Secondly, IG RTN has also been successfully applied to differentiate the difference in electron tunneling mechanism for a device under high-field or low-field stress. Finally, the soft- breakdown (SBD) behavior of a device can be clearly identified. Its IG RTN characteristic is different from that before soft-breakdown. It was found that SBD will indeed induce extra leakage current as a result of an additional breakdown path.