Crack-free Micromachining of Glass Ceramic Using Visible LIBWE

Zerodur is a glass ceramic that has zero thermal expansion coefficient. It has good optical transmission in the visible light range. The zero thermal expansion property of Zerodur makes it an important substrate material for precision optical applications such as astronomical telescope and EUVL (13 nm) lithography. In this work, we demonstrated the crack-free micromachining of Zerodur using visible laser-induced-backside-wet-etching (v-LIBWE). We used eutectic Indium Gallium alloy (In/Ga) as the light absorber for the v-LIBWE process. Spectra of the light emission during the ablation or etching were recorded and compared using the real-time monitoring method. Measuring the intensity of the characteristic emission peaks allow us to determine the etching threshold in a more efficient way.