Micromachined high-Q inductor using multi-walled carbon nanotube interconnects

Abstract

In this works, a novel high-Q inductor using multi-walled nanotube interconnects is proposed. The proposed inductor is based on 2 main ideas that (1) the inductance of the multiple paths is a few higher than that of the rigid path and (2) the extraordinary electrical properties of multi-walled nanotube, ballistic conductance and sheet current path, are used to reduce the impedance. In fabrication process, trench filled with MWNT bundle is attempt with two methods, (1) CNT paste filling process and (2) CNT droplet filling process. We shows trench is almost filled with MWNT bundle easily. With this process, CNT inductor is fabricated and measured. All the fabricated CNT inductors are malfunctioned. We find that an important rule of the pad contact resistance with MWNT. To solve this problem, the electroplating method is invited. We make the monolithic line-pad inductor filled with MWNT and encapsulate MWNT bundle with electroplated Cu to settle the pad problem. The AC and DC electrical characteristics of Cu-encapsulated CNT inductor are measured. The DC resistance is as same as Cu-line inductor. The Q-factor and inductance that is the AC characteristics are measured. The highest Q-factor of Cu-encapsulated CNT inductor is 66 that Cu-line inductor can never achieve with the same cross section area. And the performance improves 150% of the Q-factor.