Deep reactive ion etching of pyrex glass usingabonded silicon wafer as an etching mask

Abstract

A new dry-etching method for fabricating an anisotropic deep groove in Pyrex/sup /spl reg// glass is described. In the method, a 200-/spl mu/m-thick silicon wafer bonded to a Pyrex glass wafer by anodic bonding is used as an etching mask. Inductively coupled plasma generated by C/sub 4/F/sub 8/ and CHF/sub 3/ gases is also used. The measured etching rate showed that the necessary deep reactive ion etching conditions for a high etching rate are low gas pressure, high gas flow rate, high antenna power, and high bias power. The measured groove profile also showed that the sidewall angle of an etched groove is 80 degrees, which is slightly inclined off the vertical sidewall, and a fractional difference in width between the mask opening and etched groove can be found when C/sub 4/F/sub 8/ plasma is used. C/sub 4/F/sub 8/ plasma is therefore more suitable for precise groove fabrication. Even with a 430-/spl mu/m-deep groove, a 135-/spl mu/m-thick silicon mask still remained enough to fabricate a deeper groove. Consequently, our etching method using a bonded silicon mask and C/sub 4/F/sub 8/ plasma enables fabricating a deeper Pyrex glass groove.