Nanostencil Lithography for Atomic-Scale Fabrication Scale-Up

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In this project the student will develop ultrahigh vacuum (UHV) nanostencilling techniques [1] for integration withatomically-precise scanning probe microscopy (SPM) lithographies. Hydrogen resist lithography is a fabricationtechnique in which dopant atoms are incorporated into a silicon lattice, with atomic precision, using the tip of ascanning tunnelling microscope (STM) to pattern a single atomic layer of hydrogen providing a masking layer fordopant incorporation [2]. This is the only fabrication technique capable of producing deterministic, atomically-preciseelectronic devices. As such, it promises significant impact on future integrated circuit technologies and may lead toadvances in exotic device architectures such as quantum computers [3]. In order to achieve this promise, pathwaysto scale-up of atomic-scale device fabrication must be developed.UHV nanostencil shadow mask patterning is compatible with UHV-STM based fabrication, and can facilitate scale-upof atomic-scale fabrication by parallel patterning all but the finest details of a device, thus providing a contactframework within which the scanning probe can operate. In order to integrate nanostencil patterning with STMfabrication, compatible materials and processes must be developed. This requires engineering nanostencilling tools,and studying the surface and materials science of patterned structures. In this project, nanostencil shadow masks willbe designed and fabricated using standard cleanroom microfabrication techniques (electron beam lithography (EBL),Focused ion beam (FIB), etc) and then used to pattern devices in a UHV-STM system. As an integral part of thedevelopment process, layered and patterned structures fabricated at UCL will be characterised regularly using SPMat UCL and secondary ion mass spectrometry (SIMS) at Imperial, and less frequently using a variety of advanced andnovel characterization techniques at partner institutions [4], thus allowing development of both the fabricationprocesses and the measurement techniques.[1] A. Linklater and J. Nogami, Nanotech., 19, 285302 (2008).[2] T.J.Z. Stock, et. al., ACS Nano, 14, 3316 (2020).[3] C. D. Hill et. al., Sci. Adv., 1, e1500707 (2015).[4] N. D'Anna et. al., Adv. Electron. Mater., 2201212 (2023)