Scaling percussion drilling processes by ultrashort laser pulses using advanced beam shaping

摘要

Drilling processes by ultrashort laser pulses meet the demand for high-end applications in the display and electronicsindustry. Especially the manufacturing of microstructures requires highest accuracy and minimal damage of theworkpiece.A variety of applications, like the production of blind holes in multi-layer stacks or through holes in metal foils demandspecific processing constraints. For example, applications like fine metal mask (FMM) require exact rectangular holeshape as well as tailored taper angles and minimized residual particle contamination. In large scale productionenvironments, the total throughput also becomes decisive.To achieve these challenging needs, the spatial and temporal energy deposition are crucial parameters. In this context,beam shaping offers unique potential for controlling and scaling these micromachining processes. To pursue thisapproach, we present a novel adaptive beam shaping setup combined with a flexible TRUMPF TruMicro femtosecondlaser. Our investigations target percussion drilling applications with various intensity distributions. We discuss methodsfor process optimization by controlling the spatial and temporal energy deposition. This enables us to analyze thecorrelation between micromachining results and the tailored absorption.Our investigations aim on shaping several beam properties like phase, amplitude, polarization and propagationcharacteristics using a liquid-crystal-on-silicon-spatial-light-modulator (LCOS-SLM). By correcting aberrations with aclosed-loop setup, we generate robust process specific top-hat like intensity distributions.