Selective wafer bonding by surface roughness control

Selective wafer bonding is presented as a technique for fabrication of micr oelectromechanical systems (MEMS) devices with movable, contacting elements , e.g., micromachined valves. The selectivity of the wafer bonding is obtai ned by tailoring the wafer surface microroughness. The adhesion parameter i s used as the design rule for the wafer bonding technique. The technique is demonstrated with bulk micromachined check valves and a pressure actuated normally closed valve, but can be used for fabricating MEMS devices using s urface micromachining processes as well. For these valves the selective fus ion bonding technique turned out to be a convenient way to bond different w afer layers and a promising fabrication step with a high, reliable product yield. (C) 2001 The Electrochemical Society.