Patent ID: 7380460

Claim:
A pressure sensor for sensing a fluid pressure, the pressure sensor comprising: a first wafer substrate with a front side and an opposing back side, a cavity extending from the front side to the back side and a flexible membrane formed on the front side to seal the cavity; and, a second wafer at the back side of the first wafer to seal the cavity and define a chamber; the second wafer joined to the first wafer by direct wafer bonding whereby the contacting surfaces of the first and second wafers are ultra clean, and activated by making them hydrophilic or hydrophobic prior to bonding, and then brought into contact at high temperature; wherein, the chamber contains a fluid at a reference pressure, such that the flexible membrane deflects due to pressure differentials between the reference pressure and the fluid pressure; and, associated circuitry for converting the deflection of the flexible membrane into an output signal indicative of the fluid pressure.