Methodologies to enhance the resolution of electron beam lithography for nanostructure fabrication
Electron beam lithography, benefiting from the electron's shorter wavelength, is believed to be the next generation of lithography that will be used for manufacturing of ultra-large scale integrated circuits. In this dissertation, we investigated methodologies to enhance the resolution of electron beam lithography for nanostructure fabrication. The research was conducted at a writing voltage of 15 kV in order to demonstrate technologies that can be readily adapted to the future generations of commercialized electron beam lithography tools. It is expected that these new instrument will use low writing voltages in order to minimize the substrate damage and to reduce the instrument cost. Based on the studies presented in this dissertation, we demonstrate sub-10 nm linewidth isolated patterns and sub-10 nm linewidth dense patterns writing at a voltage of 15 kV. In addition, we successfully demonstrated a nano-pattern transfer process by using electron beam direct writing on a "modified" resist (in our case, a mixture of nanoparticles and PMMA photo resist). The successful demonstration of the electron beam direct writing on a modified resist can potentially open a new window of resist modification engineering for lithographic applications. The details of the development of novel methodologies will be presented in this thesis. We also demonstrate a 5 nm gold nano-gap, which can be used to study the electronic properties of nanoparticles trapped in the gap. Metal molds with minimum linewidths of 10 nm can be used for nanoimprint lithography was also demonstrated. In addition, silicon nanowires with a minimum linewidth of 10 nm that can be used for the fabrication of single electron transistor working at a high temperature were demonstrated. Finally, a 5 nm gold nanoparticle confined in a 30 nm resist island, which can be used for the single/multiple dot spectroscopy study was fabricated.