Other materials

Ceramics crack, semiconductors chip and organic materials char, each under a different kind of thermal load. Femtosecond laser pulses are over before heat leaves the focal volume, so ceramic is milled, silicon and GaAs wafers are cut clean, organics are machined without burnt edges, and dielectric surfaces are activated for metallization.

Material processing
Material processing Glass Metal Polymer Other materials
Other materials

Femtosecond processing of GaAs in air and water

Gallium arsenide (GaAs) is brittle and easily damaged by accumulated heat, so it is machined with femtosecond pulses. The result also depends on what surrounds the sample: the same pulses cut differently in ambient air and under a layer of water.

Trenches were milled in GaAs with a FemtoLux laser at 1030 nm and 900 fs, at repetition rates of 10, 50 and 200 kHz. Under a layer of water the trench depth nearly doubled, from 58 µm in ambient air to 105 µm, and the band of redeposited debris narrowed from 34 µm to 7.6 µm. Ablation efficiency was higher in water in all three regimes, about 9 µm³/µJ against 6 µm³/µJ at 10 kHz, and the gap narrowed as the repetition rate rose.

SEM image of a trench milled in GaAs under a layer of water.

SEM image of a trench milled in GaAs under a layer of water.

Courtesy of FTMC.

Trench milling parameters in water

Regime No.Average laser powerPulse repetition rateScanning speedNumber of scansFluenceHatchNumber of lines in scanTrench depth
10.4 W10 kHz50 mm/s1413.1 J/cm210 µm11105 µm
22 W50 kHz250 mm/s1413.1 J/cm210 µm1199 µm
38 W200 kHz1000 mm/s1413.1 J/cm210 µm1175 µm
Regime No.Average laser powerPulse repetition rateScanning speedNumber of scansFluenceHatchNumber of lines in scanTrench depth
Ablation efficiency of GaAs in ambient air and water environments.

Ablation efficiency of GaAs in ambient air and water environments.

Courtesy of FTMC.

Publications

Ablation Femtosecond Applications FemtoLux
GaAs ablation with ultrashort laser pulses in ambient air and water environments
E. Markauskas, L. Zubauskas, A. Naujokaitis, B. Čechavičius, M. Talaikis, G. Niaura et al., Journal of Applied Physics 133 (23), 235102 (2023). DOI: 10.1063/5.0152173.

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Optical 3D profilometer image of milled alumina squares in different operational modes.
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Cutting of FZ-Si wafer.
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