Estimating MOSFET Leakage from Low-cost, Low-resolution Fast Parametric Test

A method of estimating the subthershold component of MOSFET off-state current (I_offs) using low-cost, low-resolution fast parallel parametric test is introduced. This method measures the subthreshold slope and uses it to estimate I_offs. Measurements of individual transistors show a very good agreement between measured I_offs and I_offs estimated using our approach. For a simple pad-efficient transistor array test-structure, where unselected devices can add additional noise to the subthreshold measurements, the sum of extracted I_offs for all transistors in an array is strongly correlated to the measured array I_offs, even though it does not match the measured array I_offs. The strong correlation is used to derive calibration factors which are then used to estimate individual transistor I_offs from array test structures. This allows statistical characterization of transistor leakage during volume production with minimal test time overhead. The applications of statistical off-state leakage characterization to diagnose IDDQ yield problems during production are also described.