Abstract: A process for direct bonding similar or dissimilar materials at low temperatures in which a material surface is rendered hydrophilic and reactive by creating nitrogen based radicals on the surface, the surface is direct bonded to a second surface, and the bonded surfaces are annealed at a temperature below approximately 500.degree. C. A nitrogen based constituent is combined with an activator to render the surface hydrophilic and reactive through ammonia plasma activation or activation by use of hydrofluoric acid.

Abstract: A micromachined pressure switch and method of fabrication from silicon wafers using aligned fusion bonding. Pattern etched thermally grown silicon dioxide insulating pads are used to determine the size of silicon pressure membranes on an upper silicon wafer, with the desired switch gap set by the oxide thickness. The silicon membranes are formed by controlled thinning the upper silicon wafers. V-shaped vent grooves are pattern etched into a bottom silicon wafer to form electrodes to which the insulating pads are fusion bonded. The area between the electrodes and the membrane forms wells of specified sizes into which the membranes deflect upon application of pressure. The pressure switch operates when the membrane is deflected to contact the electrodes in the bottom wafer, and closes at the desired pressure threshold for both directions of pressure change with negligible hysteresis. The method of fabrication applies to a single element pressure switch as well as to an array of pressure switches.

Abstract: A process for precision alignment and bonding of complementary micromechanical, electrical and optical structures. Surface features of the structures are critically aligned and brought into physical contact within atomic dimensions to form direct bonds without the use of adhesives. The bonds are initially formed at room temperature and then strengthened by a high temperature anneal. Three dimensional structures may be formed in separate prefabricated layers rather than monolithically through the use of this process.