Investigation Of Integration Technology Of Carbon Nanotubes Micro-vias Interconnect

With the rapid development of integrated circuit(IC) and the increase of wiring density,interconnection line will carry up to107A/cm2of current density. Both the increasing of RCsignal delay, electromigration phenomenon and the decreasing of heat dissipation greatlyaffect the reliability of the chip. Carbon nanotubes(CNTs) are attractive material for nextgeneration IC interconnects materials due to the reason that they can carry high currentdensity(1010A/cm2) and have highly thermal conductivity and resist ability ofelectromigration. However, the MWCNTs growth model makes it close-ended, high inherentresistivity and high contact resistance with electrode. Meanwhile，it is not clear that CNTsgrowth mechanism in micro-vias. Those disadvantages whittle down the CNTs application ininterconnect.This paper try to realize CNTs interconnection structure and optimize its electricalproperties by Focused ion beam(FIB). The minimum array of2μm diameter dielectricmicro-vias was fabricated by dry etching, through the end point detection curve ofCurrent-Depth. The advantages and disadvantages of two kinds of mainstream ICinterconnection materials aluminum and copper were compared in CNTs interconnection.Then,50nm aluminum as a buffer layer was deposited on copper electrode which effectivelysolve the pollution of the catalyst by copper ion diffusion before the high density anddirectional property of CNTs were formed in the micro-vias. Meanwhile, it was designed thatthe top electrode structure to facilitate test. It was a good guarantee for electricalcharacterization of CNTs interconnection structure.Next, FIB was used to cut the end of CNTs to improve its electrical conductivity. Thecutting method, aperture and growth height of CNTs were studied respectively. Then, it wasdescribed that the Height-Resistance curves of pre-cutting and post-cutting CNTsinterconnection structure. Make the inherent resistivity of CNTs and the contact resistancewith top electrodes separated. Further evidence cutting the top of CNTs with platinumprotected layer by FIB can effectively optimize their electrical properties and I-V linearity.The results showed, CNTs interconnection structure of2μm diameter micro-vias, comparingwith no treatment the inherent resistivity of CNTs (508.8m.cm) and the contact resistancewith top electrodes (439), it achieved a lower inherent resistivity of CNTs (81.2m.cm)and the contact resistance with top electrodes (31) that the top of CNTs were cut by FIB. Anorder of magnitude was reduced, respectively.Lastly, according to describe the Height-Times curves of CNTs growing ininterconnection structure, it was explored that the growth mechanism of CNTs in Micro-viasand the ways to improve the growth height of CNTs.