tailieunhanh - Solid State Circuits Technologies_2

Tham khảo sách 'solid state circuits technologies_2', kỹ thuật - công nghệ, hoá học - dầu khí phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 12 Carbon Nanotube Interconnect Technologies for Future LSIs Mizuhisa Nihei Akio Kawabata Motonobu Sato Tatsuhiro Nozue Takashi Hyakushima Daiyu Kondo Mari Ohfuti Shintaro Sato and Yuji Awano MIRAI-Selete Japan 1. Introduction Carbon nanotubes CNTs are attractive as nanosize structural elements from which devices can be constructed by bottom-up fabrication. A CNT is a macromolecule of carbon and is made by rolling a sheet of graphite into a cylindrical shape. CNTs exhibit excellent electrical properties that include current densities exceeding 109 A cm2 and ballistic transport along the tube. Because of these factors with their large electro-migration tolerance and low electrical resistance CNTs can be used as nano-size wiring materials and are thus becoming potential candidates for future LSI interconnects. Much effort has been made to produce CNT vias which use bundles of MWNTs multi-walled carbon nanotubes as vertical wiring materials as shown in Figure 1. Sato et al. demonstrated low-resistance CNT vias employing a novel metallization technology which used preformed catalyst metal particles to grow dense MWNT-bundles by thermal chemical vapor deposition CVD . Low-k CNT via MWNT Fig. 1. Schematic of future LSI interconnects consisting of CNT vias and low-k materials. The advantage of CNT-bundles is their low resistance which may be the solution to the problem of high resistance in scaled-down vias. As shown in Fig. 2 we estimated the resistance of a 50-nm-diameter via depending on the filling rate of CNTs in the via area. In this estimation we assumed that CNTs have the quantum resistance Rq h 4e2 kọ conductance GQ 2GQ0 4e2 h which reaches the maximum conductance limit for ballistic transport in two channels of a CNT that current flows through each shell of MWNTs and that there is no dependence of ballistic transport on CNT length. In order to lower the 228 Solid State Circuits Technologies resistance of CNT vias it is necessary to increase the nanotube s .