Capacitance Analysis of Highly Leaky $\hbox{Al}_{2} \hbox{O}_{3}$ MIM Capacitors Using Time Domain Reflectometry

Abstract

Characterization of metal-insulator-metal (MIM) capacitors with a scaled dielectric is a challenge using conventional capacitance–voltage ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$C$</tex></formula> – <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$V$</tex></formula> ) measurements due to a high leakage current. In this letter, a method to analyze MIM capacitance that is more immune to the leakage current problem has been successfully demonstrated using time domain reflectometry (TDR). The TDR method can be applied to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\hbox{Al}_{2}\hbox{O}_{3}$</tex></formula> MIM capacitors with a capacitance density up to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim\!\!\hbox{11.1}\ \hbox{fF}/\mu\hbox{m}^{2}$</tex></formula> , for which an impedance analyzer has failed to measure capacitance at 1 MHz. Differences in the voltage coefficient of capacitance and dielectric constant ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$k$</tex></formula> ) were also investigated.