Nanomolding of Topological Materials for Interconnect Applications

Student’s name: Richard Remias       Home Institution: University of Rhode Island NNCI Site: CNF @ Cornell University REU Principal Investigator: Dr. Judy Cha, Materials Science and Engineering, Cornell University REU Mentor(s): Quynh Sam & Khoan Duong, Materials Science and Engineering, Cornell University Abstract: The increasing resistivity of copper (Cu) interconnects with decreasing dimensions poses many challenges for the continued downscaling of integrated circuits and computer chips. At the nanoscale, electron scattering at grain boundaries and surfaces of the interconnects causes an increase in resistivity leading to higher energy consumption and signal delay in computer chips. Conversely, topological materials may show decreasing resistivity with decreasing size at nanoscale dimensions due to their topologically protected band structures that are predicted to suppress electron scattering. Thus, transport studies of topological materials at the nanoscale are critical to find alternative metals to Cu interconnects. Nevertheless, current nanowire synthesis methods such as molecular beam epitaxy (MBE) and chemical vapor transport (CVT) struggle to create uniformly sized nanowires. We use nanomolding to fabricate nanowires of topological materials, where a bulk material is pressed into a porous anodic aluminum oxide (AAO) mold to create high aspect ratio nanowires. To promote more facile nanomolding and to prevent oxidation of the molded nanowires, we coat the AAO mold pore walls with a thin film of aluminum nitride (AlN). The CNF’s Oxford FlexAl atomic layer deposition (ALD) tool is used to deposit precise and uniform films due to its self-limiting reactions. Through energy dispersive X-ray spectroscopy (EDX), we determine the infiltration depth of AlN in our pores. Additionally, InBi is a topological material which may exhibit interesting quantum properties at few-layer thicknesses. We use nanomolding to compress InBi into thin flakes by encapsulating the InBi with hexagonal boron nitride (hBN). The CNF’s AFM Veeco Icon tool is used to determine the resulting thickness of the InBi flake.