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

Characterization of metal-insulator-metal (MIM) capacitors with a scaled dielectric is a challenge using conventional capacitance–voltage ($C$– $V$) 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 $\hbox{Al}_{2}\hbox{O}_{3}$ MIM capacitors with a capacitance density up to $\sim\!\!\hbox{11.1}\ \hbox{fF}/\mu\hbox{m}^{2}$, for which an impedance analyzer has failed to measure capacitance at 1 MHz. Differences in the voltage coefficient of capacitance and dielectric constant ($k$) were also investigated.