A new method to determine MOSFET channel length

Abstract

A new method is proposed to electrically determine MOS transistor channel length with both accuracy and convenience. Based on the linear region relationship between effective channel length L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</inf> and channel resistance R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">chan</inf> of an MOS transistor, this method determines L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</inf> by applying relatively large but constant gate voltage to eliminate threshold voltage determination and takes into account external resistance. Comparison of this method with SEM measurement shows very good agreement (within ±0.1 µm resolution limit of our SEM technique).