Development of Test Structure for Variability Evaluation using Charge-Based Capacitance Measurement

A test structure for charge-based capacitance measurement (CBCM) method has been developed to evaluate the threshold voltage variability from capacitance-voltage (C-V) curves of actual size metal-oxide-semiconductor field-effect-transistors (MOSFETs). The C-V curves from accumulation to inversion are measured for the MOSFETs having various channel dimensions using this test structure. Intrinsic capacitance components between the MOSFET electrodes are extracted from those C-V curves which are considered to include parasitic capacitance component. The intrinsic C-V curves are used for attempting to extract threshold voltage variations of their MOSFETs. It is found that the developed test structure is very useful for the evaluation of MOSFETs variability, because the derivation in MOSFET C-V curves is not influenced by current measurement noise.