Dynamic deformation and fracture of single crystal silicon: Fracture modes, damage laws, and anisotropy. (1st August 2016)

• Record Type: Journal Article
• Authors: Huang, J.Y.; E, J.C.; Huang, J.W.; Sun, T.; Fezzaa, K.; Xu, S.L.; Luo, S.N.
• Is Part Of: Acta materialia. Volume 114(2016)
• Page Start: 136
• Page End: 145
• Publication Date: 2016-08-01
• Subjects: Single-crystal Si -- Dynamic fracture -- Cleavage -- X-ray imaging -- Laue diffraction; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2016.05.022
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: Impact fracture of single-crystal Si is critical to long-term reliability of electronic devices and solar cells for its wide use as components or substrates in semiconductor industry. Single-crystal Si is loaded along two different crystallographic directions with a split Hopkinson pressure bar integrated with an in situ x-ray imaging and diffraction system. Bulk stress histories are measured, simultaneously with x-ray phase contrast imaging (XPCI) and Laue diffraction. Damage evolution is quantified with grayscale maps from XPCI. Single-crystal Si exhibits pronounced anisotropy in fracture modes, and thus fracture strengths and damage evolution. For loading along [1 1 ¯ 0] and viewing along [001], ( 1 ¯ 1 ¯ 0 )[1 1 ¯ 0] cleavage is activated and induces horizontal primary cracks followed by perpendicular wing cracks. However, for loading along [01 1 ¯ ] and viewing along [111], random nucleation and growth of shear and tensile-splitting crack networks lead to catastrophic failure of materials with no cleavage. The primary-wing crack mode leads to a lower characteristic fracture strength due to predamage, but a more concentrated strength distribution, i.e., a higher Weibull modulus, compared to the second loading case. Moreover, the sequential primary cracking, wing cracking and wing-crack coalescence processes result in a gradual increase of damage with time, deviating from theoretical predictions. Particle size and aspect ratios of fragments are discussed with postmortem fragment analysis, which verifies fracture modes observed in XPCI. Graphical abstract: