Tunable MEMS capacitors using vertical carbon nanotube arrays grown on metallines

Abstract

In this work, tunable MEMS capacitors are realized using a vertically grown carbonnanotube array. The vertical CNT array forms an effective CNT membrane, which canbe electrostatically actuated like the conventional metal plates used in MEMScapacitors. The CNT membrane is grown on titanium nitride metal lines, with aAl/Fe bi-layer as buffer layer and catalyst material respectively, using chemicalvapor deposition process. Two different anchor configurations are investigated. Amaximum capacitance of 400 fF and maximum tunability of 5.8% is extracted from theS-parameter measurements. Using the tunable MEMS vertical array capacitor a voltagecontrolled oscillator (VCO) is demonstrated showing promise for integrating CNTs forcommunications applications.