Ablation of metals and semiconductors with ultrashort pulsed lasers: improving surface qualities of microcuts and grooves

Abstract

Femtosecond laser systems offer a good solution for the creation of straight microcuts and grooves on macroscopic workpieces, as they are becoming more established in industrial applications. Although such linear ablation processes have been investigated and improved before, the main obstacle is still the long processing time. Increasing the processing speed by applying high pulse energies usually leads to a significant quality loss. Using high pulse repetition rates at low pulse energies would lead to the best results, but the repetition rate of commercially available laser sources is mostly restricted to one to several kilohertz. However, a systematic investigation of further relevant parameters enables the processing quality and speed to be optimized. To demonstrate these relations, cuts and grooves using different motion parameters and focusing strategies are presented at the example of metal and silicon samples. With regard to the focusing strategy, it is shown that by using linear focus shapes in the direction of the cut, cutting speeds can be increased while maintaining high edge qualities of the cuts and grooves. The presented results prove the potential of femtosecond lasers for high quality cuts in different industrially relevant materials.