Brittle Failure of Nanoscale Notched Silicon Cantilevers: A Finite Fracture Mechanics Approach

Pasquale Gallo,Alberto Sapora

doi:10.3390/app10051640

Pasquale Gallo, Alberto Sapora

Open Access

https://doi.org/10.3390/app10051640

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Abstract

The present paper focuses on the Finite Fracture Mechanics (FFM) approach and verifies its applicability at the nanoscale. After the presentation of the analytical frame, the approach is verified against experimental data already published in the literature related to in situ fracture tests of blunt V-notched nano-cantilevers made of single crystal silicon, and loaded under mode I. The results show that the apparent generalized stress intensity factors at failure (i.e., the apparent generalized fracture toughness) predicted by the FFM are in good agreement with those obtained experimentally, with a discrepancy varying between 0 and 5%. All the crack advancements are larger than the fracture process zone and therefore the breakdown of continuum-based linear elastic fracture mechanics is not yet reached. The method reveals to be an efficient and effective tool in assessing the brittle failure of notched components at the nanoscale.

Highlights

Recent technological developments have enabled the fabrication of electronic devices with high-density integration
The dimensionless apparent generalized fracture toughness is plotted in Figure 3 versus the dimensionless notch root radius ρ/lch, where lch = (K Ic /σu )2 ≈ 5.18 nm is the so called “Irwin’s length”
The present work sheds light on the applicability of the Finite Fracture Mechanics (FFM) approach by using experimental data available in the literature related to blunt V-notched nano-cantilevers, made of single crystal silicon

Summary

Introduction

Recent technological developments have enabled the fabrication of electronic devices with high-density integration. At a very small scale, the simplification of a body as continuum and homogeneous may not hold, and the discrete nature of atoms should be considered [6,7,8] Clarification of these aspects could bring enormous development in the field of nanotechnology, but macroscale could benefit as well, e.g., multi-scale modeling of fatigue with focus on short cracks and interaction with local micro-structure [9,10], atomistic investigation of stresses, strains and grain boundaries [11], fracture properties of advanced materials [12,13], experimental evaluation of fatigue curve of microscale samples [14]

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