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MM: Fachverband Metall- und Materialphysik

MM 15: Poster session I

MM 15.35: Poster

Monday, March 7, 2016, 18:00–20:00, Poster B3

Microstructure Effects on Nanometric Cutting Behavior of Silicon — •Alexander Stukowski¹ and Saurav Goel² — ¹Technische Universität Darmstadt — ²School of Mechanical and Aerospace Engineering, Queen's University, Belfast, UK

Silicon is being used extensively in both single crystal and polycrystalline form for a wide range of applications. To enable the production of ultra-thin wafers for future microelectronic applications, it is vital to fully understand the mechanical response of the material at small length scales.

We use direct molecular dynamics simulation to study the mechanisms of plasticity during cutting of monocrystalline and polycrystalline silicon. Our simulations are based on an improved long-range potential, providing a more accurate picture of the atomic-scale mechanisms of fracture, ductile plasticity, and structural changes in Si.

The simulation results show a unique phenomenon of brittle cracking inclined at an angle of 45° to 55° to the cut surface, leading to the formation of periodic arrays of nanogrooves in monocrystalline Si, which provides new insights into previously published experimental results. Furthermore, during cutting, silicon is found to undergo solid-state directional amorphisation without prior Si-I to Si-II phase transformation, which is in direct contrast to many previously published MD studies on this topic. Our simulations also predict that the propensity for amorphisation is significantly higher in single crystal silicon than in polysilicon, signifying that grain boundaries ease the material removal process.