Film bulk acoustic-wave resonator and method for manufacturing the same

1. A film bulk acoustic-wave resonator comprising:

a substrate having a cavity, the substrate being formed of one of semi-insulating material and high-resistivity material;

a bottom electrode partially fixed to the substrate, part of the bottom electrode is mechanically suspended above the cavity;

a piezoelectric layer disposed on the bottom electrode, the shape of the piezoelectric layer is defined by a contour;

a top electrode on the piezoelectric layer;

a semiconductor intermediate electrode buried at and in a surface of the substrate, being located at the contour of the piezoelectric layer, the semiconductor region having a lower resistivity than the substrate, the intermediate electrode is connected to the bottom electrode in the inside of the contour; and

a bottom electrode wiring connected to the semiconductor intermediate electrode extending from the contour to an outside of the contour in the plan view,

wherein a longitudinal vibration mode along a thickness direction of the piezoelectric layer is utilized.

2. The film bulk acoustic-wave resonator of claim 1 , further comprising:

an inter-layer dielectric film formed on the piezoelectric layer, the semiconductor substrate being laid bare from the contour of the piezoelectric layer and the semiconductor intermediate electrode,

wherein through a first contact window formed in the inter-layer dielectric film, the top electrode is electrically connected to the piezoelectric layer and through a second contact window formed in the inter-layer dielectric film, the bottom electrode wiring is electrically connected to the semiconductor intermediate electrode.

3. The film bulk acoustic-wave resonator of claim 2 , wherein the cavity is an open cavity implemented by a through-hole penetrating the substrate along a direction from the bottom surface of the substrate to the top surface of the substrate for exposing a bottom surface of the bottom electrode.

4. The film bulk acoustic-wave resonator of claim 2 , wherein the cavity is a closed cavity implemented by a groove dug at a top surface of and in the substrate.

5. A method for manufacturing a film bulk acoustic-wave resonator, comprising:

forming a semiconductor intermediate electrode on a semiconductor substrate, the semiconductor intermediate electrode having a lower resistivity than the semiconductor substrate;

stacking a metallic film for forming a bottom electrode on the entire surface of the semiconductor substrate so as to include the semiconductor intermediate electrode;

stacking a piezoelectric dielectric film on the entire surface of the bottom electrode and on the semiconductor intermediate electrode;

delineating the piezoelectric dielectric film and the metallic film with an identical etching mask so as to form the piezoelectric layer and the bottom electrode, the piezoelectric layer has a same shape and a same size as the bottom electrode in a plan view, the bottom electrode is connected to the semiconductor intermediate electrode;

forming a top electrode on the piezoelectric layer; and

forming a bottom electrode wiring so as to be connected to the semiconductor intermediate electrode.