Evaluation of MOSFET C-V curve variation using test structure for charge-based capacitance measurement

Test structure for charge-based capacitance measurement (CBCM) is improved, to achieve higher accuracy of measuring capacitance-voltage (C-V) curves for actual size MOSFETs. Capacitance mismatch between the device under test (DUT) and the reference is avoided by using charge-injection-induced-error-free CBCM (CIEF CBCM) method. To increase the applicable bias voltage range to DUT, both P- and N-channel MOSFETs are parallel-connected in the pseudo-inverter. It is found that the C-V curves, which are measured with this test structure and are corrected by removing the size effect, are very close to the C-V relation measured by the conventional method, and then, the corrected capacitances give more accurate gate capacitances of MOSFETs.