Effect of localized KrF excimer laser treatment on fracture behaviors of freestanding <110> and <100> single crystal silicon beams

Microscale silicon structures oriented along <100> and <110> orientations were laser treated with different conditions with the cross section shape and tensile strength investigated after the treatment. Finite element simulation was performed to examine the temperature distribution at different conditions during laser treatment. Using a low energy (1.2 J/cm²) and high tilt angle (65°) led to a more preserved cross section with a slight strength improvement. The strength improvement was limited due to other surfaces that were not affected by laser treatment. An improvement of 30 % in tensile strength was achieved with a higher energy (4 J/cm²) lower tilt angle (45°) treatment that was consistent for different sample orientations. The cross section of the samples treated at such condition was significantly changed however. The effect of sample orientation on fracture behaviour was studied and unstable crack propagation was observed for <100> oriented samples that was more significant after laser treatment.