Deep reactive ion etching of Pyrex glass

Abstract

We have developed a deep reactive ion etching of Pyrex glass in SF/sub 6/ plasma. High etch rate (/spl sim/0.6 /spl mu/m/min) and smooth surface (Ra-4 nm) were achieved at low pressure (0.2 Pa) and high self-bias (-390 V). This result indicates energetic ions for physical sputtering and for enhancing chemical reactions are required to etch materials which produce nonvolatile reaction products. Vertical etch profile (base angle /spl sim/88/spl deg/), high aspect ratio (>10) and through-out etching of Pyrex glass (200 /spl mu/m in thickness) were achieved when the mask opening is narrower than 20 /spl mu/m. Relatively low selectivity to the mask material due to the energetic ion is overcame using thick and vertical electroplated Ni film as a mask. We also find out the base angle of the etch profile depends on the mask profile and the opening width.