Extraction of Mobility Degradation and Source-and-Drain Resistance in MOSFETs
Keywords:MOSFET, mobility degradation, source-and-drain resistance, parameter extraction, indirect bidimensional fitting
A MOSFET model parameters extraction procedure that overcomes the difficulties of separating the effects of source-and-drain series resistance and mobility degradation factor is presented. Instead of the conventional direct fitting, the present procedure involves the use of indirect bidimensional fitting of the source-to-drain resistance of a single device, as obtained from the below-saturation output characteristics measured at several above-threshold gate voltages. The procedure is verified with a simulated long channel FinFET device with externally added resistances and is later applied to experimental planar bulk DRAM MOSFET devices with channel lengths ranging from 0.23μm to 2.0μm. The procedure is shown to be advantageous in terms of computational efficiency and it is appropriate even with high values of externally added series resistances. For the case of devices with various channel lengths, the accuracy of the procedure is improved if the value of RSD is extracted from the shortest channel length. This value of RSD could be used for extracting the other parameters for devices with longer channel.