LOW-TEMPERATURE WAFER BONDING OF SURFACES USING A REACTIVE SPUTTERED OXIDE

A low-temperature silicon wafer bonding technique has been demonstrated to give bond strengths as high as 2.4 MPa for anneal temperatures as low as 400-degrees-C. The technique involves RF magnetron reactive sputter deposition of nonstoichiometric SiOx(x < 2) films on one or both surfaces prior to contacting at room temperature. Surfaces investigated include bare silicon, thermally grown silicon dioxide, and low pressure chemical vapor deposited silicon nitride. Experimental results provide new evidence that removal of oxygen or water from the bonding interface during annealing is critical to the formation of strong interfacial bonds.