Use of an Elastomeric Donor for LIFT of Metal Foils

Laser-induced backside wet etching (LIBWE) is a method for the precise etching and structuring of SiO2.In this study, LIBWE is performed by using ultrashort laser pulses with a pulse duration of τ = 500 fs and a wavelength of λ = 515 nm.Saturated aqueous KMnO4 solution is the absorbing liquid for the LIBWE process.The observed etching rate is approximately 10 -3 nm/pulse, which is substantially lower than that in previous reports; it increases with increasing laser fluence.The initial etching rate decreases with higher pulse numbers until it approaches a stable value.After the LIBWE, the generated etching pits are partially covered by MnOx layers with thicknesses of tens of nanometers.However, at the etched SiO2 surface, two different laser-induced periodic surface structures (LIPSS) are found.In the center of the etching pits, LIPSS with a period of λHSFL ≈ (52 ± 2) nm are observed, whereas in the outer areas, LIPSS with a period of λLSFL ≈ (390 ± 20) nm are found.The etching mechanism for the LIBWE of SiO2 with aqueous KMnO4 solution is proposed to comprise laser-based heating, decomposition of KMnO4, and chemical etching of the SiO2 surface by the produced KOH.