An improved method employed in anodic bonded glass-silicon gyroscopes to avoid footing effect in DRIE

The SGADER (silicon glass anodic-bonding and deep etching release) technology is developed by Peking University. Many MEMS devices have used this technology, as accelerometers, changing capacitor and micro-gyroscope etc. In the fabrication of these devices by SGADER technology, the bottom damage of the silicon combers and cantilever beams caused by the footing effect is always a serious problem. We have developed feasible methods by patterning about 0.2 μm metal film to evacuate charges during over etching time, and got a manifest benefit in the SGADER process. Some comparison has been made to illustrate the effectivity of this addition disposure. A serious consideration must be taken during the design of the whole layout to minimize the parasitic problem brought by metal film left on the glass. It is very important to pay attention to the electrical relationship between the metal film and every silicon structure.