Profile control of a borosilicate-glass groove formed by deep reactive ion etching

We investigated the deep reactive ion etching (DRIE) of borosilicate glass and profile control of an etched groove. We carried out DRIE using an anodically bonded silicon wafer as an etching mask. We controlled the glass-groove profile, namely improving its sidewall angle, by removing an excessive polymer film produced by carbon-fluoride etching gases during DRIE. We experimentally compared two fabrication processes for effective removal of the polymer film: (1) DRIE with the addition of argon (Ar) to the etching gases and (2) a novel combined process in which DRIE and subsequent ultrasonic cleaning in DI water were alternately carried out. Both processes improved the sidewall angle, reaching 85 degrees independent of the mask-opening width. The results showed that the processes remove the excessive polymer film on sidewalls. Accordingly, the processes are an effective way to control the groove profile of borosilicate glass.