Contents I. Introduction
The conventional split-capacitance–voltage (–) measurement at low frequency [1] has been successfully demonstrated as a necessary tool to extract basic gate stack parameters such as equivalent oxide thickness (EOT), flat-band voltage , channel doping, and mobility [2], [3]. However, this tool has not been demonstrated yet for the most advanced devices of interest in the semiconductor industry. The test of leaky and short-channel devices poses a dramatic challenge for basic gate stack characterization due to the limited sensitivity of conventional metrology apparatus and the long measuring times needed. The leakage effect can be minimized by increasing the capacitance signal through the increase of the measurement frequency, but to do this correctly, it is imperative to use microwave techniques. The gate capacitance measurement at high frequency in the presence of high leakage has already been demonstrated by Schmidtz et al. [4] by using MOSFETs connected as two-port amplifiers, with the source and bulk tied to the ground. By grounding the drain port, they were able to measure the gate-to-all capacitance at frequencies in the range of 0.5–1 GHz for very leaky and small devices. In the literature, this method has been denominated as RFCV [3], [4]. However, due to the layout of the connections (source and bulk shorted), could not be separated into its two components, namely 1) the gate-to-bulk or accumulation capacitance and 2) the gate-to-channel or inversion capacitance . The accurate determination of these capacitances is imperative to determine the average channel mobility [2], [3].
