Chip-Scale Localized Synthesis of Carbon Nanotubes on Copper Microstructures via Inductive Heating

Synthesis of carbon nanotubes has been successfully demonstrated by locally heating suspended ring-shaped copper microstructures on a silicon substrate using an inductive heating system. Silicon specimen with electrodeposited copper rings of varying geometries were placed at different locations along the induction coil axis, and synthesized CNTs were obtained only on the locally-heated microstructures with none found on the substrate. An analytical expression for the normalized, generated EMF was derived for the induction heater revealing a quadratic dependence of the EMF with ring radius, and a local maximum of the normalized EMF at an axial distance of 6.55mm from the coil center. These trends were supported using high resolution CCD imaging. The average diameters of the predominantly base-growth CNTs increased from 8.1nm to 9.5nm from the hottest location to a distance of 120mum from the hottest location along the microstructure. No CNTs were synthesized beyond 220mum from the hottest spot. IV data were obtained illustrating a CNT resistance of HOkO. Also, localized synthesis of CNTs occurred on silicon specimen with multiple ring-shaped microstructures. As a result, such a synthesis method could be used to locally heat microstructures at a wafer scale for parallel synthesis and integration of CNTs.