Elastic recovery of monocrystalline silicon during ultra-fine rotational grinding

Abstract

Micromachining of brittle materials like monocrystalline silicon to obtain deterministic surface topography is a 21 st Century challenge. As the scale of machining has shrunk down to sub-micrometre dimensions, the undulations in the machined topography start to overlap with the extent of elastic recovery (spring back) of the workpiece, posing challenges in the accurate estimation of the material's elastic recovery effect. The quantification of elastic recovery is rather complex in the grinding operation due to (i) randomness in the engagement of various grit sizes with the workpiece as well as (ii) the high strain rate employed during grinding as opposed to single grit scratch tests employed in the past at low strain rates. Here in this work, a method employing inclination of workpiece surface was proposed to quantify elastic recovery of silicon in ultra-fine rotational grinding. The method uniquely enables experimental extraction of the elastic recovery and tip radius of the grits actively engaged with the workpiece at the end of the ultra-fine grinding operation. The proposed experimental method paves the way to enable

Molecular dynamics simulation of AFM tip-based hot scratching of nanocrystalline GaAs

“…It is well known that the hardness and yield strength of a hard, brittle material decreases at higher temperatures [10] and the fracture toughness increases with the increase of temperature [11]. To this end, nanometric cutting of GaAs substrates at room temperature was recently investigated by the authors [12] and some conceptual fundamental aspects of room-temperature cutting of GaAs and the wear of diamond tool were discussed.…”

Simulation of the ductile machining mode of silicon

“…At h c u = 500 n m , the elastic recovery is around 400 n m and for h c u = 1000 n m and h c u = 1500 n m about 200 n m . In comparison with experimental results obtained from grinding of silicon with grains of similar average size (≈ 25.3 μ m ) and cutting speed of v c = 44 m / s [ 36 ], the simulated recovery depth is higher for small depth of cut and lower for high depth of cut. Recovery depth of , , and were observed in the grinding experiments.…”

“…7 Workpiece discretisation and meshed single grain diamond Fig. 8 Temperature dependent Young's modulus E<100> [14] used in this investigation For ductile material removal, indentation theory proposed by Oliver and Pharr [35] and a model developed and validated for single grain scratching of silicon by Huang et al [36] is applied to consider elastic recovery, with the assumption that the grain tip is spherical. For a spherical indenter, the actively engaged tip radius can be determined from the residual scratch width and the contact depth.…”

New insights into the methods for predicting ground surface roughness in the age of digitalisation

“…However, as the scale of machining shrinks to sub-micrometer dimensions, the undulations in the machined topography start to overlap with the extent of elastic recovery of the workpiece, posing challenges in the accurate estimation of material's elastic recovery. In a recent work [41,42], the authors of this paper proposed a novel method to quantify the elastic recovery of silicon during ultra-fine rotational grinding. Experimental results showed that this method will reliably estimate the elastic recovery and the tip radius of active grits.…”