Passive Mask Charge Control for Improved Reactive Ion Etching of Silicate Glasses

Inhalt:
This contribution investigates the influence of passive charge control on the etching behavior of silicate glasses in the reactive ion etching (RIE) process. A special conductive hard mask made of chromium enables different charge states simultaneously in an etching process. One part of the mask has a floating potential, while the other part is electrically connected to the bias electrode. Due to this, a direct comparison of the influence of both charging states can be carried out. When etching fused silica and Borofloat 33 in a CF4 plasma, we found that the regions electrically connected to the bias electrode rather than a floating potential enabled an increase in etching rates up to 10 % but also influenced the overall roughness of the etched structures. These findings facilitate more efficient dry chemical etching of glass, yielding higher etching rates and enhanced structural fidelity with no additional resource requirements.