ABSTRACT
Semiconductor Research Corporation in its International Technology Roadmap of Semiconductors report (ITRS 2003) has referred to several non-classical devices, which could be the candidates of future technology to replace the existing silicon MOSFETs as the end of Moore’s law approaches year 2020 [1]. Double-gate MOSFET and FinFET are recognized as two of the most promising candidates for future very large scale integrated (VLSI) circuits [2-5]. The carbon nanotube field-effect transistor (CNT-FET) is regarded as an important contending device to replace silicon transistors [6-7] since many of the problems that silicon technology is facing are not present in CNTs. For example, carrier transport is 1-D in carbon nanotubes; the strong covalent bonding gives the CNTs high mechanical and thermal stability and resistance to electromigration; and diameter is controlled by its chemistry and not by the standard conventional fabrication process [2].For interconnects, as CMOS processes scale into the nanometer regime, lithography limitations, electromigration, and the increasing resistivity and delay of copper interconnects have driven the need to find alternative interconnect solutions [8]. Carbon nanotubes have emerged as a potential candidate to supplement copper interconnects because of their ballistic transport and ability to carry large current densities in the absence of electromigration [9]. Previous studies that assess the potential use of CNTs as
interconnects [10-13] primarily focus on the relative interconnect delay of CNTs to copper for sub-nanometer CMOS technology nodes. Carbon nanotubes are being explored extensively as the material for making future complementary devices, integrated circuits [14-16], interconnects [17], and hybrid CMOS/nanoelectronic circuits [18]. In the following, some insight into the carbon nanotube as a material, realization of field-effect transistor and interconnection for integrated circuits will be presented. 1.1 Introduction-Carbon NanotubesIn 1960, Bacon of Union Carbide [19] reported observing straight hollow tubes of carbon that appeared as graphene layers of carbon. In 1970s, Oberlin et al. [20] observed these tubes again by a catalysis-enhanced chemical vapor deposition (CVD) process. In 1985, random events led to the discovery of a new molecule made entirely of carbon, 60 carbons arranged in a soccer ball shape [21]. In fact, what had been discovered was an infinite number of molecules: the fullerenes, C60, C70, C84, etc., every molecule with the characteristic of being a pure carbon cage. These molecules were mostly seen in a spherical shape. However, it was until 1991 that Iijima [22] of NEC observed a tubular shape in the form of coaxial tubes of graphitic sheets, ranging from two shells to approximately 50. Later, this structure was called multi-walled carbon nanotube (MWCNT). Two years later, Bethune et al. [23] and Iijima and Ichihashi [24] managed to observe the same tubular structure, but with only a single atomic layer of graphene, which became known as a single-walled carbon nanotube (SWCNT).
