Influence of the burst mode onto the specific removal rate for metals and semiconductors Available to Purchase

For most applications the benefit of the burst mode can performed. It was found that for surface structuring with a Gaussian beam the specific removal rate in terms of removed volume per pulse energy or removed volume per time average power reads easily be explained: The energy of each pulse in a n-pulse burst is n times smaller compared to single pulses with identical average power repetition rate. Thus, the peak fluence of each pulse is nearer the optimum value the removal rate is therefore increased. But it is generally not as high as it would be if single pulses with identical peak fluence but n-times higher repetition rate could be applied.

But there are situations where the burst mode can lead to higher efficiencies i.e. specific removal rates and a real increase in the removal rate can be obtained. For copper, 1064 nm and a 3-pulse burst the specific removal rate amounts to about 118% of a single pulse. For silicon a huge increase from 1.62 µm³/µJ to 4.92 µm³/µJ was observed by applying an 8-pulse burst. Based on calorimetric measurements on copper and silicon the increased absorptance resulting from a rougher surface is identified as an effect which could be responsible for this increase of the specific removal rate. Thus, the burst mode is expected to be able to influence surface parameters in a way that higher efficiencies of the ablation process can be realized.