Machining of [100], [110] and [111] oriented silicon with ultrashort laser pulses in the NIR

[100], [110] and [111] oriented silicon shows different behavior when it is machined with 10 ps pulses in the NIR. For the [100] orientation the roughness increases to 2.8 µm when the peak fluence is raised to 1.6 J/cm2 then drops down to a value below 200 nm for a fluence of 2 J/cm2 and stays below 300nm for fluences up to 7.5 J/cm2. For the other orientations a completely different behavior is observed. The roughness constantly increases to 900 nm at 1.6 J/cm2 and then further to about 8 µm for a peak fluence of 7.5 J/cm2.