Patent ID: 7662655

Claim:
A method for forming a hermetically sealed vibrating micromechanical structure, the method comprising: in a base wafer formed of one of an insulating wafer and a Silicon-On-Insulator wafer, forming one or more resonator anchors adjacent to a capacitive air gap; in a resonator wafer formed of a Silicon-On-Insulator wafer having a single crystal silicon semiconductor material active layer and a semiconductor material handle layer separated by a dielectric layer, coupling the active layer directly to the resonator anchors of the base wafer; removing the handle and dielectric layers of the Silicon-On-Insulator resonator wafer; in the single crystal silicon semiconductor material active layer of the Silicon-On-Insulator resonator wafer, silicon dry etch micromachining a single crystal silicon resonator; forming one or more contact pads on an outer surface of the resonator wafer active layer; in a cover wafer formed of a single crystal silicon (SCS) semiconductor material, forming a cover having a plurality of access holes through the wafer between the spaced apart top and bottom surfaces and each access hole being aligned with a corresponding one of the contact pads on the outer surface of the resonator wafer active layer, and wherein forming the cover further comprises: etching one or more frit trenches surrounding an interior area of the wafer bottom surface corresponding to the resonator in the active layer of the Silicon-On-Insulator resonator wafer, and etching one or more frit trenches surrounding areas of the wafer bottom surface corresponding to each access hole; screen printing frit bonding material in each of the frit trenches; and in a chamber enclosing a controlled atmosphere, frit bonding the cover to the active layer of the resonator wafer with the frit trenches surrounding the interior area being positioned surrounding the resonator and the frit trenches surrounding areas corresponding to each access hole being aligned with a corresponding one of the contact pads.