US 7,478,562 B2 · High temperature LC pressure transducer and methods for making the same

Abstract

A high temperature pressure capacitor is fabricated utilizing two high temperature substrate wafers. The substrates may be silicon carbide (SiC) or aluminum nitride (AIN). The first substrate has a metal conductive plate positioned on a top surface thereof. The top surface and plate are covered with a dielectric layer. The second substrate has a plate accommodating recess on the top surface thereof. Deposited in the recess is a second conductive plate. The first and second wafers are bonded together via the dielectric layer where the first and second plates face each other. Upon application of a force to the first wafer the diaphragm portion of the first wafer deflects causing the first plate to move and thereby varying capacitance. An inductor may be fabricated on a bottom surface of the second wafer to provide an LC circuit whose resonant frequency varies as a function of capacitance and therefore as a function of pressure.

Claims20

Dependent claims

A high temperature pressure variable capacitor, comprising:

a first high temperature semiconductor wafer having a top and bottom surface and having a first conductive capacitor plate positioned on the top surface, said first wafer of a thickness enabling deflection upon application of a force to said bottom surface thus acting as a diaphragm;
a dielectric layer covering said top surface and said plate;
a second high temperature semiconductor wafer having atop and bottom surface and having a plate-accommodating depression etched into the top surface to a given depth, a second conductive plate located in said depression and relatively congruent to said first plate, said top surface of said first wafer bonded to said top surface of said second wafer, with said second plate facing said first plate and separated therefrom by a gap, said gap forming a capacitor between said first and second plates, whereby when a force is applied to the bottom surface of said first wafer said diaphragm deflects to change the gap between said plates and a capacitance between said first and second plates.

Dependencies are inferred from the claim text.

High temperature LC pressure transducer and methods for making the same

Life of this patent

High temperature LC pressure transducer and methods for making the same

Life of this patent

Abstract

Claims20