A new method for the work-function difference determination using buried-channel MOS transistors

A method is presented that is based on measuring the dependence of the threshold voltage on the source-bulk bias for a series of buried-channel MOS transistors with different gate oxide thicknesses. The measurement is made in the depletion and in the accumulation-punchthrough modes of operation. It is a DC measurement and is therefore compatible with other test measurements. The implementation of the method for process control purposes is straightforward since only the threshold voltage of the BCMOSFET must be determined. As the exact knowledge of the surface doping is not needed, and there is no effect due to interface-traps capacitance, the method is believed to be more accurate than the standard C-V technique