(Invited) Atomistic Insights into Continuous and Area-Selective ALD Processes: First-Principles Simulations of the Underpinning Surface Chemistry

Abstract

Atomic layer deposition (ALD) is a highly advanced thin film deposition technology that has found widespread use in nanoelectronics, photovoltaics, fuel cell and recently all-solid-state battery applications. It is widely regarded as the state-of-the-art technique for producing thin films due to its exceptional conformality on high-aspect ratio structures, atomic level thickness control, and tuneable film composition. In recent years, area-selective atomic layer deposition (AS-ALD) has emerged as a promising technology for high-fidelity nano-patterning, and significant progress has been made in understanding and developing highly selective processes for various material systems. Along these lines, we have recently shown that high-throughput, low defectivity, highly selective SiO2 deposition can be achieved on various substrates by combining atmospheric-pressure spatial ALD with integrated area-deactivation using small molecule inhibitors and plasma-enhanced spatial etching [1].ALD is a surface-controlled technique that relies on the self-limiting reactions of the precursors and co-reactants with the deposition surface in alternating cycles. The initial step in ALD nucleation on the target substrate is a key factor in the deposited film quality, and efficient precursor binding on the surface is critical. Molecular dynamics (MD) simulations and minimum-energy reaction pathway analysis based on ab initio Density Functional Theory (DFT) calculations provide invaluable insights into the surface chemistry, enabling customisation of ALD processes to boost uniformity, conformality, and area-selectivity of the resulting films.In this talk, I will discuss how first-principles simulations can be used synergistically with experimental findings to achieve high-efficiency plasma-enhanced atomic-layer cleaning (ALC) of impurities from various ALD films and substrates, design proper chemical surface modifications that enable continuous and conformal ALD nucleation even on chemically-inert surfaces (like graphene), and unveil the particular surface chemistry governing high-fidelity area-selectivity with an atomic-level precision in ultrathin coatings [1-9]. By combining the insights gained from first-principles simulations with experimental techniques, we can push the frontiers of device manufacturing to new heights, opening up exciting possibilities for further technological advances in nanoelectronics, photovoltaics, fuel cell and energy storage applications.[1] Advanced Materials, Just Accepted, (DOI: 10.1002/adma.202301204); [2]Nanoscale, 2021, 13, 10092-10099; [3] Chem. Mater. 2019, 31 (4), 1250-1257.; [4] Adv. Mater. Interfaces 2018, 5 (13), 1800268.; [5] Chem. Mater. 2017, 29 (3), 921–925.; [6] ACS Nano 2017, 11 (9), 9303–9311.; [7] Sol. Energy Mater. Sol. Cells 2017, 163, 43–50.; [8] Chem. Mater. 2017, 29 (5), 2090–2100.; [9] Nanoscale 2016, 8 (47), 19829–19845. Figure 1