Insight into Atomic-Scale Adhesion at the C–Cu Interface During the Initial Stage of Nanoindentation

Abstract

Adhesion is a common phenomenon in nanomachining which affects processing accuracy and repeatability. As material removal approaches the atomic or close-to-atomic scale, quantum mechanics becomes the dominant principle behind the atomic-level interaction. However, atomic-scale effects cannot be properly described by empirical potential function-based molecular dynamics simulations. This study uses a first-principles method to reveal the atomic-scale adhesion between a diamond tip and a copper slab during initial-stage nanoindentation. Using a simplified tip and slab model, adhesion energy, electronic distribution, and density of states are analyzed based on quantum chemistry calculation. Results show that atomic adhesion is primarily due to the covalent bonding interaction between C and Cu atoms, which can induce structural changes to the diamond tip and copper slab. The effects of tip position and angles on adhesion are further studied through a series of simulations. The results show that adhesion between the tip and slab is sensitive to the lattice structure and a variant in angstroms is enough to cause different adhesion and structural changes. The actual determinants of adhesion can only be the atomic and electronic structures at the tip–slab interface. Bond rotation and breakage are observed during simulation and their effects on adhesion are further discussed. To conclude, the first-principles method is important for the analysis of an atomic-scale interaction system, even if only as an aid to describing adhesion at atomic and electronic scales.

Anisotropic Effects in Local Anodic Oxidation Nanolithography on Silicon Surfaces: Insights from ReaxFF Molecular Dynamics

“…Reactive force field molecular dynamics (ReaxFF MD) simulation has emerged as a preferred approach for investigating the intricate reaction mechanisms in various nanomanufacturing processes at nanometric and even atomic scales. , It is capable of elucidating bonding interactions, chemical compositions, and atomic dynamics while offering reduced computational cost compared to first-principles methods. − ReaxFF MD simulations have been employed to extensively study silicon surface wet oxidation processes, which are modeled in a similar scenario to that of the LAO process. Pamungkas et al examined the initial stage of silicon (001) oxidation by water, revealing that hydrogen atoms in water bond with silicon more readily than oxygen atoms in O 2 .…”

Atomistic Insights into Bias-Induced Oxidation on Passivated Silicon Surface Through Reaxff Md Simulation

“…Reactive force field (ReaxFF) MD simulation is an ideal method for handling chemical reactions within a large number of molecules. It not only offers irreplaceable advantages in elucidating bonding interaction, chemical composition and atomic dynamics behaviours, but also saves the computational cost when using first-principles methods [6,10,11]. This method has been successfully applied in the studies of surface oxidation [12][13][14][15][16][17][18][19][20], chemical mechanical polishing [21][22][23][24][25][26], nanoscale contact and tribology [27][28][29].…”