A self-consistent extraction procedure for source/drain resistance in MOSFETs

A new method to determine source/drain series resistance has been developed for MOSFETs operated in linear region. The source/drain resistance (RSD) is gate-bias dependent. Channel length reduction (ΔL) is extracted at low gate bias and chosen to be constant. All parameters extracted in this method are assumed to be independent of mask channel length for model simplicity. The method has been applied to devices with mask channel lengths of 0.23, 0.2, and 0.185 μm. The extracted parameters are consistent with the assumptions and have been validated by measured I–V characteristics.

► The source/drain resistance varies with gate bias, while the effective channel length is assumed bias-independent.
► Measured devices: channel width W = 10 m and mask channel lengths Lm = 0.185, 0.2, and 0.23 m, oxide thickness of 40Å.
► Weak bias dependence of source/drain resistance is assumed at low gate bias, consistent with some published results.
► All extracted parameters are independent of mask channel length, which causes an error of 0.53% or lower in model playback.
► A fully accurate model can be obtained if source/drain resistance is allowed to vary with mask channel length.