Submicron micromachining on silicon wafer using femtosecond pulse laser

Laser machining of submicron grooves on silicon wafer by 400 nm femtosecond laser is studied. A chirped pulse amplification based Ti:sapphire system that produces pulse with a pulse duration of 150 fs at a repetition rate of 1 kHz is used. Focusing lens with numerical aperture of 0.36 focuses the laser beam into a 3 μm laser spot (by calculation). The sample was translated at a linear speed of 400 μm/s during machining. 500 nm wide 100 nm deep groove was obtained on the wafer when the sample was irradiated by pulses with energy of ∼50 nJ/pulse and 800 nm wide 650 nm deep groove was obtained by pulse with energy of ∼100 nJ/pulse.