Anodic bonding below 180°C for packaging and assembling of MEMS using lithium aluminosilicate-β-quartz glass-ceramic

Abstract

Silicon-to-glass anodic bonding is performed at temperature below 180/spl deg/C using lithium aluminosilicate-/spl beta/-quartz glass-ceramic. High alkaline ion mobility at low temperature which is required for bonding and thermal expansion coefficient matching to Si is realized by controlling the composition of the glass-ceramic. Bonding is obtained at the lowest temperature of 140/spl deg/C. Useful bonding conditions are temperature above 160/spl deg/C (applied voltage of above 500 V). Since the etch rate of the glass-ceramic is five times higher than that of Pyrex glass in HF wet etching and the undercut is very small with Cr-Au etch mask, three dimensional structures are easily fabricated. Low temperature anodic bonding using this type of glass-ceramic is useful for the packaging and assembling of MEMS.