DEEP WET ETCHING OF BOROSILICATE GLASS USING AN ANODICALLY BONDED SILICON SUBSTRATE AS MASK

Deep wet etching of borosilicate glass using an anodically bonded sili con substrate as mask is presented. Depths of 500 mu m or more can be achieved very easily. The structured glass wafer can be bonded anodica lly on the same side to another silicon wafer, alter having removed th e bonded silicon mask. A lateral underetching 1.5 times larger than th e depth was measured. An application using this masking technique is a lso presented. It consists of using the anodically bonded frame of a r esonant silicon structure as a mask for deep glass etching to increase the gap between the glass wall and the resonator, thus yielding a hig h Q-factor.