Time-resolved imaging and simulations of SiO₂films dynamic fracture due to laser-induced confined micro-explosion at Si/SiO₂interface

Confined laser-matter interactions can be initiated by short laser pulses either in a transparent medium through nonlinear absorption in the focal region of a tightly focused beam, or at the interface of a film/substrate system, one of which is transparent for laser radiation. In the latter case, a near-interface confined micro-explosion at a certain energetic threshold leads to a localized fracture of the film above the irradiated area. The process was recently studied using 1-4m thick SiO 2 films grown on Si wafers by PECVD [1]. It was noted that at certain conditions, the fracture leads to ejection of a conoid/disk-like flyer, often found intact nearby the irradiation site. This phenomenon is of interest for a relatively novel class of additive microfabrication processes - the laser-induced forward and backward transfer (LIFT and LIBT) of functional materials in solid phase. Flyer ejection during LIBT of solid polymer films was previously studied using time-resolved imaging [2].