Temporal pulse shaping for tailored materials processing of dielectrics and semiconductors

Bandgap materials from glass and sapphire for display to semiconductors for microelectronics represent a huge and ever-growing market. Processing these materials with femtosecond lasers -like dicing, cleaving, cutting hole drilling etc.- has gained a substantial market share. Optimal pulse duration, peak intensity and temporal pulse shapes depend on the bandgap width and material-specific nonlinear coefficients. To address multiple photon iononization (MPI) and avalanche ionization processes separately, more flexible temporal pulse shapes are needed: A leading fs part with high peak intensity to create free carrier electrons by MPI and a trailing ps to ns pulse to heat the electrons in the preconditioned channel of the beam propagation by avalanche ionization. In the present study we will compare conventional fs pulse ablation studies with tailored temporal pulse shapes on various material like fused silica sapphire and silicon. We will present the according material removal rates to evaluate the optimization potential for temporal pulse shapes.