MSE Thesis Defense: “Ultra-High-Resolution Patterning and Pattern Transfer via Nanocrystal Colloidal Lithography”

The ability to design, pattern, and process materials at the nanoscale has enabled vast research opportunities ranging from fundamental science to technological applications and device integration. The continued development of nanoscience and nanotechnology relies upon pushing the limits of nanoscale fabrication capabilities. After decades of development, this frontier has moved to the sub-10 nm length scale to explore novel physical properties and functionalities for next-generation technology. However, conventional “top-down” strategies that have carried nanofabrication to this point have severe limitations for practically improving the resolution capabilities of deep nanoscale fabrication. In this dissertation, we demonstrate ultra-high-resolution patterning and pattern transfer using nanocrystal (NC) colloidal lithography. This innovative nanofabrication platform integrates bottom-up methods, that combine NC synthesis and self-assembly approaches, with well-established top-down techniques such as dry etching and thin film deposition.

We employ monodisperse NC building blocks with self-assembly methods to establish high-density, well-ordered patterns, where the inorganic core of each NC serves as a discrete hard mask used for high-fidelity pattern transfer into a desired substrate material. We demonstrate the use of isotropic NCs to establish various sub-10 nm pattern morphologies and examine the stability of the NC pattern upon dry etching, comparing NC monolayers and bilayers. We extend the NC colloidal lithography scheme using anisotropic NCs to demonstrate high-density, anisotropic pattern transfer into various substrate materials down to the sub-5 nm regime. The presented fabrication strategy offers further opportunities to leverage various combinations of NC morphologies and materials afforded by the extensive NC library for more complex pattern design. Additionally, this approach can be extended to process various substrate material classes at the deep nanoscale. The NC colloidal lithography platform enables broader access to single-digit nanoscale fabrication for the scientific community worldwide, which could impact various research sectors ranging from integrated circuits to memory devices, optoelectronics, metasurfaces, quantum devices and more.