Fracture dynamics in implanted silicon

Abstract

International audienceCrack propagation in implanted silicon for thin layer transfer is experimentally studied. The crack propagation velocity as a function of split temperature is measured using a designed optical setup. Interferometric measurement of the gap opening is performed dynamically and shows an oscillatory crack "wake" with a typical wavelength in the centimetre range. The dynamics of this motion is modelled using beam elasticity and thermodynamics. The modelling demonstrates the key role of external atmospheric pressure during crack propagation. A quantification of the amount of gas trapped inside pre-existing microcracks and released during the fracture is made possible, with results consistent with previous studies. (C) 2015 AIP Publishing LLC

Brittle fracture studied by ultra-high-speed synchrotron X-ray diffraction imaging

“…The angular separation just behind the crack indicates a 'wedge' shape of the crack opening. This is consistent with IR interferometry measurements of the crack opening (Massy et al, 2015) and optical reflection measurements (Ronseaux et al, 2021). From linear elastic fracture mechanics, the profile is parabolic in the close vicinity of the crack front, as strain varies as K/(x 1/2 ), with K the stress intensity factor.…”

“…In addition, the crack opening following the crack front creates air wedge interference fringes, which are visible in the transmitted signal from the IR photodiode. These signals can be used for dynamic measurement of the crack velocity and give detailed information on the vibrations of the wafers associated with the crack front propagation, including acoustic (Lamb) waves (Massy et al, 2015(Massy et al, , 2018. Finally, in our experiment, the samples were pre-annealed to develop microcracks up to the desired microcrack surface coverage, and a motor-driven blade was used for mechanical induction of the fracture at room temperature.…”

Crack Front Interaction with Self-Emitted Acoustic Waves

“…The substrate is then bonded onto a host wafer using direct wafer bonding [35], [36]. Under annealing, the implanted species evolve into microcracks lying parallel to the surface, and a controlled fracture finally propagates along the implanted layer (mainly 2D propagation) [37], [38]. If not thermally, the fracture can be mechanically initiated after a certain degree of maturation by pushing a blade between the two wafers.…”

“…1(a)). To monitor the crack propagation, a dedicated optical bench based on infrared transmission in silicon has been developed [38]. The crack is mechanically initiated by a blade which is inserted at the beveled edge of the sample.…”

“…The time lag between the two intensity drops on the laser signals allows the determination of the crack velocity which is here 2.4±0.1 km.s -1 . The following oscillations correspond to laser interferences due to crack opening and can be used to recover the crack deformation profile [38].…”