Patent ID: 7662654

Claim:
A method for forming a hermetically sealed vibrating micromechanical structure, the method comprising: in a cover wafer having substantially planar and spaced apart top and bottom surfaces, forming a cover, including: forming a plurality of access holes through the cover wafer between the spaced apart top and bottom surfaces; preparing the cover wafer bottom surface for bonding in a bonding pattern at least surrounding each of the access holes and surrounding an interior area of the wafer bottom surface; etching a pattern of frit trenches in the cover wafer bottom surface, the pattern including one or more first frit trenches surrounding each of the access holes and one or more second frit trenches surrounding an interior area of the wafer bottom surface; further comprising screen printing frit bonding material in the first and second frit trenches; and in a controlled atmosphere, bonding the cover with a micromechanical resonator device having a resonator etched in a single crystal silicon semiconductor material active layer of a Silicon-On-Insulator resonator wafer and further comprising a base wafer coupled to the single crystal silicon resonator, including joining the cover to the active layer of the resonator wafer with the bonding pattern of the first frit trenches and the second frit trenches surrounding the interior area of the wafer bottom surface being positioned to completely surround the resonator, and the access holes being aligned with contact pads formed on the active layer of the resonator wafer.