Measurement of Threshold Voltage and Channel Length of Submicron MOSFET's.

Source and drain series resistance becomes significant in submicron channel length MOSFET's and can cause large errors in traditional methods for transistor characterization. We describe a simple and accurate method for measurement, in the linear region, of threshold voltage and channel length of submicron MOSFET's. Measurements on 0.4 - 1.0micron channel length LDD transistors with series resistance 3.4 - 14 kOMEGA micron show that our method gives threshold voltage accurate to within 5 mV whereas the commonly used linear I sub D - V sub G extrapolation method consistently underestimates the threshold voltage by more than 100 mV at small channel lengths. Channel length accuracy of our method is 0.02micron whereas the method of Suciu and Johnston, used at Final In-Process Testing (FIPT), overestimates channel length by about 0.15micron. For the 0.9micron CMOS technology developed at Allentown, we find nominal and minimum channel lengths of 0.6 and 0.45micron.