高导电铜/碳纳米管（Cu/CNT）纳米线制造及导电机理研究

The line-width of interconnects in integrated circuits (IC) with high performance has been greatly reduced following the well-known Moore law. Copper (Cu) is the main interconnect metal material currently being used in IC. However, the continuous downscaling of line-width has caused two technology barriers associated with Cu interconnects including electromigration and largely increased resistivity. The increased resistivity not only increases the RC delay in the computation to low the performance but also causes servere electromigration as well as Joule heating related reliability concerns. According to the free electron gas theory of the electrical conductivity (inverse of the resistivity) of metal in quantum mechanics, this project aims to develop a novel Cu/Carbon nanotube (Cu/CNT) nanowire with high conductivity that crystalline Cu filled continuously in CNT templates to realize good interfacial bonding ensuring electron redistribution between CNT and Cu. Then the ultrahigh conductivity of Cu/CNT nanowire could be obtained by combining the large free electron density (from Cu) and large mean free path (from CNT). An innovative manufacturing process to achieve copper tightly bonded into inner CNT and to realize electron redistribution between copper and CNT is proposed to achieve large electron free mean path and large free electron density at the boundary. The fabrication process of high-conductive Cu/CNT nanowire at large area can be described as follows: The ordered channel of the anodic alumina Oxide (AAO) template is prepared with two-step anodic oxidation of aluminum. The catalysts are electrodeposited into the nanochannel of AAO template. Patterned growth of CNT array with opened end in AAO template is conducted using chemical vapor deposition. Then the electrochemical deposition will be performed to deposit continuous crystalline Cu into nano hole in CNT to form tightly interfacial bonding with CNT. The unifom Cu/CNT nanowires at large area will form after the etching away of the AAO template. In the end, the electrical conductivity, electromigration and conductive mechanism of fabricated Cu/CNT nanowire will be investigated by combining four-probe measurement with the first principle calculation for the application realibity as interconnect in IC. These Cu/CNT nanowires are promising as building blocks for assembling advanced interconnects to overcome current technology barriers in IC including electromigration and increased electrical resistivity. The fabrication process of the Cu/CNT nanowire was compatible with the traditional IC process. The success of this project will also make significant impacts on nanoscale integated circuits due to the ultrahigh conductivity and high antielectromigration potentials of Cu/CNT nanowires.Also the ultra-high conductive Cu/CNT nanowires could be applied as electrodes of bio/chemical sensor.

集成电路集成度不断提高，铜互联线宽减小而导致电阻率显著增大，增大RC时延而降低性能，加剧电迁移和焦耳热相关可靠性问题。基于量子力学金属导电自由电子气理论，项目提出纳米尺度铜紧密填充碳纳米管(CNT)兼得高自由电子密度(从铜)和长电子平均自由程（从CNT）的高导电铜/碳纳米管（Cu/CNT）纳米线理论。以多孔氧化铝（AAO）为模板化学气象沉积开口CNT，再以开口CNT为模板，电化学紧密填充铜，最后去除AAO模板，大面积制造高导电Cu/CNT纳米线。开发四电极法精确测试单根Cu/CNT纳米线的导电率和承受电流密度，结合纳米线结构表征，研究结构因素对导电影响及机理。从原子层面设计和构建Cu-CNT界面结构的Cu/CNT复合体系，基于第一性原理系统计算其电子和导电特性，深入研究高导电Cu/CNT纳米线的导电机理。高导电Cu/CNT纳米线有望应用于未来高性能集成电路，还可作先进生物化学传感器的电极。

集成电路集成度不断提高，铜互联线宽减小而导致电阻率显著增大，增大RC时延而降低性能，加剧电迁移和焦耳热相关可靠性问题。基于量子力学金属导电自由电子气理论，项目提出了纳米尺度铜填充碳纳米管(CNT)高导电铜/碳纳米管（Cu/CNT）纳米线理论。首先开发了以多孔氧化铝（AAO）为模板化学气象沉积开口CNT，再以开口CNT为模板，电化学紧密填充铜，最后去除AAO模板，获得铜填充CNT的复合纳米线制造工艺；进一步调整各个步骤的工艺参数，控制CNT的可控生长，阳极氧化、CVD生长CNT、扩孔、电化学沉积获得不同直径的Cu/CNT纳米线包括铜纳米颗粒，铜纳米柱，铜纳米线不同形态的Cu/CNT复合纳米线，通过对Cu/CNT复合纳米线的表征，铜与CNT的界面具有紧密结合特性，具有潜在的优异电学特性。开发四电极法精确测试单根Cu/CNT纳米线的导电率和承受电流密度，结合纳米线结构表征，对比分析单根一维铜纳米线，单根碳纳米管以及Cu/CNT复合纳米线等电学特性，为Cu/CNT纳米线的电子传输特性测试打下基础。从原子层面设计和构建Cu-CNT界面结构的Cu/CNT复合体系，基于第一性原理系统计算其电子和导电特性，制造不同构型的铜填充CNT的Cu/CNT纳米线，研究铜原子填充CNT的电子特性设，基于第一性原理的密度泛函理论计算铜填充CNT的态密度、能带、分波态密度研究了高导电Cu/CNT纳米线的导电机理，铜金属修饰的碳纳米管结构，有效提高碳纳米管的投射系数。通过AFM研究不同电压下金属和石墨烯表面作用，研究金属在正负偏压下金属针尖和石墨烯之间表面力随电压的变化规律，获得随着电压值的增加而增加，针尖和石墨烯之间固有的电势差导致正电压下的静电粘附要低于负电压下的静电粘附，并且固有电势差的影响会随着电压值的增加被不断放大，电压的大小和方向对金属和石墨烯表面作用的有重要影响特性，并且通过电场控制金属和石墨烯界面的特性调控，实现金属对石墨烯界面的可控调控。高导电Cu/CNT纳米线有望应用于未来高性能集成电路，还可作先进生物化学传感器的电极，还可以应用于微纳高灵敏传感器件。