Microindentation for Fracture and Stress‐Corrosion Cracking Studies in Single‐Crystal Silicon

Abstract

Simple microindentation techniques have been applied to investigate fracture and stress-corrosion cracking in singlecrystal silicon. The results obtained agree with the previously reported data obtained from conventional methods. Fracture toughness of silicon in {110}/{112} orientations was measured to be 1.00 +-0.08 MPa m '/2. No evidence of stresscorrosion cracking in silicon in both air and water environments was observed even at a temperature moderately above room temperature. An interpretation for this lack of stress-corrosion cracking has been proposed. These microindentation techniques, which have high spatial resolutions, are potentially useful for mechanical integrity assessment of siliconbased electronic components.

Mechanisms for Fatigue of Micron‐Scale Silicon Structural Films

“…High-resolution infrared imaging of the fatigue specimen revealed only minimal temperature changes (~1K) during testing, which strongly implied that the enhanced notch root oxidation was not thermally induced but mechanical in origin [11] . As discussed below, since the cracking processes occurs within the oxide layer, this mechanism is consistent with the fact that bulk silicon is not susceptible to environmentally-induced cracking in air [9,16,28,34] . This image shows stable cracks, ~50 nm in length, in the native oxide formed during cyclic fatigue loading; testing of this sample was interrupted after 3.56 × 10 9 cycles at a stress amplitude σ a = 2.51 GPa.…”

“…It was quickly discovered by Connally and Brown [4] that the delayed failure under cyclic loading for micron-scale silicon differed from the macroscale behavior of the material. Silicon is a brittle material that does not exhibit any dislocation activity at low homologous temperatures [5] , any extrinsic toughening mechanisms [6] , or any evidence of susceptibility to environmentallyassisted cracking [7][8][9] . Based on this information and knowledge of macro-scale fatigue mechanisms [10] , silicon should not fatigue at room temperature and thus the findings of…”

Fracture Behavior of Nanoscale Notched Silicon Beams Investigated by the Theory of Critical Distances

“…Also, the fracture toughness is in good agreement with the values reported for the macroscale. [21,23,[42][43][44] This demonstrates that the fracture behavior of silicon is not affected by the size and that nanoscale mechanisms govern the macroscale behavior. On this last point, TCD can yield important findings and further results that are detailed in the Discussion section below.…”

A reaction-layer mechanism for the delayed failure of micron-scale polycrystalline silicon structural films subjected to high-cycle fatigue loading

“…indeed, the threshold stress intensity, K scc , for such cracking is much less than K c , i.e., typically K scc ~ 0.25 MPa√m, in contrast to silicon where K scc ≈ K c [14][15][16]. Indeed, such effects have recently been suggested for subcritical crack growth in borosilicate glass [41].…”

“…Moreover, silicon is not susceptible to environmentally-induced cracking (stress-corrosion cracking) in moist air or water [14][15][16] at growth rates measurable in bulk specimens. These observations strongly suggest that silicon should not fatigue at room temperature.…”