Patent ID: 7432781

Claim:
A fabrication method of a monolithic duplexer, the method comprising: forming a plurality of elements spaced from each other on a top portion of a device wafer; forming first sealing parts on opposite ends of the top portion of the device wafer and forming a plurality of first ground planes between the plurality of elements; partially etching a surface of a cap wafer, which packages the device wafer, to form protrusions on opposite ends of the cap wafer, and to form a plurality of ground posts between the protrusions such that cavities are formed between the protrusions and the ground posts; forming second sealing parts on bottom portions of the protrusions and forming a plurality of second ground planes which cover the plurality of ground posts; forming via holes penetrating the cap wafer to connect to the plurality of second ground planes and forming ground terminals on top portions of the via holes; and bonding the device wafer and the cap wafer to form each of the ground posts between each of the plurality of elements.