Deep plasma etching of glass with a silicon shadow mask

Inductively coupled plasma reactive ion etching (ICP RIE) has been successfully used for deep (>300 μm) etching of silica and glass with a non-bonded silicon shadow mask. A standard silicon wafer as the mask, many laborious processing steps are avoided and the mask can be used many times. Aspect ratios exceeding 3:1 have been achieved with 400 μm silicon wafer mask by tuning the source and bias powers, gas composition and pressure. It is of major importance to optimize the etching process for deep etching silica glass when a bonded silicon mask is not be used. In this work, effects of plasma etching conditions to etch performance were studied to optimize the plasma etching process for the clamped silicon mask wafer.