An impedance-phase angle (Z-theta) method for capacitance extraction of ultra-thin gate dielectrics at intermediate frequency [MOS devices]

Traditional C-V measurement is not accurate for extraction of gate oxide thickness below 15 Å due to high gate leakage current. In this paper, without using such a high frequency approach as S-parameter extraction, we propose a new approach using Z-theta (impedance-phase angle) measurement and a more comprehensive equivalent circuit model. A parameter extraction tool (PET), consisting of HSPICE simulator and a least square optimizer, is developed to extract the gate capacitance from the Z-theta measurement and a new equivalent circuit model. This method can account for parasitic effects, such as stray capacitance induced by chuck and inductance at high frequency. We demonstrated that this proposed approach has the capability to measure the gate capacitance correctly down to 10 Å.