Error and Correction in Capacitance–Voltage Measurement Due to the Presence of Source and Drain

MOS capacitor with highly leaky gate dielectric requires source and drain to support the inversion charges. This transistor-like capacitor for capacitance-voltage ( -) measurement has become popular due to the need of accurately measuring inversion capacitance. The source and drain overlap capacitance is an unavoidable error and must be quantified. Although it is possible to measure the overlap capacitance directly, conventional method is not reliable due to high leakage. Here, we show that this error can be corrected in the new time-domain-reflectometry - measurement method introduced recently for highly leaky capacitors.

Since MOSFET operates at inversion, the inversion capacitance is an important parameter to be measured accurately. The extraction of oxide thickness also depends on accurate knowledge of the inversion capacitance. When the gate oxide is very thin, the traditional MOS capacitor test structure for capacitance–voltage (– ) measurement can no longer be used for inversion capacitance extraction because the generation-limited inversion charges are leaked across the thin oxide layer [1]. As a result, the transistor-like capacitor structure with source and drain to provide inversion charge has become popular for obtaining low-frequency-like – curve using high-frequency measurement [2]–[5].