Fabrication of silicon-based nano-structures and their scaling effects on mechanical and electrical properties

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Title: Fabrication of silicon-based nano-structures and their scaling effects on mechanical and electrical properties
Author: Li, Bin, 1974 May 21-
Abstract: Silicon -based nanostructures are essential building blocks for nanoelectronic devices and nano -electromechanical systems (NEMS ) , and their mechanical and electrical properties play an important role in controlling the functionality and reliability of the nano -devices . The objective of this dissertation is twofold : The first is to investigate the mechanical properties of silicon nanolines (SiNLs ) with feature size scaled into the tens of nanometer level . And the second is to study the electron transport in nickel silicide formed on the SiNLs . For the first study , a fabrication process was developed to form nanoscale Si lines using an anisotropic wet etching technique . The SiNLs possessed straight and nearly atomically flat sidewalls , almost perfectly rectangular cross sections and highly uniform linewidth at the nanometer scale . To characterize mechanical properties , an atomic force microscope (AFM ) based nanoindentation system was employed to investigate three sets of silicon nanolines . The SiNLs had the linewidth ranging from 24 nm to 90 nm , and the aspect ratio (Height /linewidth ) from 7 to 18 . During indentation , a buckling instability was observed at a critical load , followed by a displacement burst without a load increase , then a fully recoverable deformation upon unloading . For experiments with larger indentation displacements , irrecoverable indentation displacements were observed due to fracture of Si nanolines , with the strain to failure estimated to be from 3 .8 % to 9 .7 % . These observations indicated that the buckling behavior of SiNLs depended on the combined effects of load , line geometry , and the friction at contact . This study demonstrated a valuable approach to fabrication of well -defined Si nanoline structures and the application of the nanoindentation method for investigation of their mechanical properties at the nanoscale . For the study of electron transport , a set of nickel monosilicde (NiSi ) nanolines with feature size down to 15 nm was fabricated . The linewidth effect on nickel silicide formation has been studied using high -resolution transmission electron microscopy (HRTEM ) for microstructural analysis . Four point probe electrical measurements showed that the residual resistivity of the NiSi lines at cryogenic temperature increased with decreasing line width , indicating effect of increased electron sidewall scattering with decreased line width . A mean free path for electron transport at room temperature of 5 nm was deduced , which suggests that nickel silicide can be used without degradation of device performance in nanoscale electronics .
URI: http : / /hdl .handle .net /2152 /3740
Date: 2008-08-29

Citation

Fabrication of silicon-based nano-structures and their scaling effects on mechanical and electrical properties. Doctoral dissertation, The University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /3740 .

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