Some Investigation On Carbon Nanotubes And Graphene As Interconnect In Nanoscale Integrated Circuits

In recent years, with the rapid development of information and nanoelectronics technology, the feature size of VLSI is decreasing from submicroscale to nanoscale, this means that microelectronic has been developed into the era of nanoscale. In modern high-speed large-scale integrated nanoscale circuits, due to interconnect has been reduced to nanoscale region with the increasing of metal resistivity, it is going to encounter some problems, such as electron mobility, degradation of thermal properties and the whole system reliability issue. Therefore, the electrical characteristics and thermal properties of the interconnect line analysis will be one of the key technologies in the new generation of nanoscale circuits.With the discovery of carbon nanotubes and graphene, they play an increasingly important role in the integrated circuit due to the excellent properties that they have in the on-chip interconnects and vias. Therefore, this dissertation focuses on the application of carbon nanotubes and graphene in future nanoscale circuits. This dissertation first introduces the background of nanoelectronics, then presents the research status of carbon nanotubes and graphene, finally discusses their structure、electrical、thermal and other characteristics in interconnect and via study.The main academic contributions of this dissertation are as follows:1. Equivalent circuit model of single-walled carbon nanotube interconnects is derived. There are three main distribution circuit parameters:resistance, capacitance and inductance.2. According to the derived transfer function and the equivalent circuit model of single-walled carbon nanotube bundle interconnect, their stability as well as signal transmission characteristics are studied in this paper. Also, compact expressions that describe the transient response of single and two coupled carbon nanotube bundle interconnects are presented to enable physical insight and accurate estimations of the time delay and crosstalk for carbon nanotube bundle interconnects.3. Electrothermal modeling of through silicon multi-walled carbon nanotube bundle via (TS-MWCNTBV) interconnects is performed in this paper. A set of equivalent lumped-element circuit models for two, three and four TS-MWCNTBV geometries are at first proposed, with quantum effects treated appropriately. The methods for characterizing their frequency-and temperature-dependent per-unit-height RLCG parameters are then given. They are applicable for low-, medium-and high-resistivity silicon substrates, respectively. Further, parametric studies are performed for single MWCNT bundle, single TS-MWCNTVB,3-and4-TS-MWCNTBV, respectively, with mutual electromagnetic coupling taken into account.4. Signal transmission characteristics of some multilayer graphene nano-ribbon (MLGNR) interconnects are studied in this paper, with an equivalent single-conductor (ESC) model implemented for the analysis of their transient responses. In this model, both capacitive and inductive couplings between adjacent GNR layers are treated appropriately. According to the derived transfer function using the fourth-order approximation, the output voltage waveforms are predicted. In particular, the effects of Fermi level of MLGNR on the time delay of the transmitted rectangular pulse are examined and compared. Further, the crosstalk between the edge-coupled MLGNR interconnects excited by a rectangular pulse have been obtained.