A Novel Technique for Probing the Vertical Component of FinFET Source Resistance

Abstract

We propose and demonstrate, with hardware, the first experimental technique to measure a vertical component of FinFET source resistance. Forward bias is applied to the well-to-source p-n junction, and the forward voltage at constant current density, <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$V_{{fb}}$</tex> </formula> , is measured as a function of source-current, <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$I_{ds}$</tex> </formula> . The source-current, <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$I_{ds}$</tex> </formula> , is varied by variation of <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$V_{gs}$</tex> </formula> , and an effective vertical resistance is calculated, <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$R_{ve} =$</tex> </formula> dV <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$_{fb}$</tex> </formula> /dI <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$_{ds}$</tex> </formula> . Significant self-heating effects of the p-n junction are observed, and we demonstrate a technique to correct <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$V_{fb}$</tex> </formula> for the local rise in temperature. We find that our technique gives well-behaved results for vertical source resistance. Quantitative <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$R_{ve}$</tex> </formula> values are found to be consistent with technology characterization of (linear region) total device resistance.