Manufacturing process for thin film bulk acoustic resonator (FBAR) filters
Method for fabricating an acoustical resonator on a substrate having a top surface. First, a depression in said top surface is generated. Next, the depression is filled with a sacrificial material. The filled depression has an upper surface level with said top surface of said substrate. Next, a first electrode is deposited on said upper surface. Then, a layer of piezoelectric material is deposited on said first electrode. A second electrode is deposited on the layer of piezoelectric material using a mass load lift-off process.
1 - 16 . (canceled)
17 . An acoustical resonator comprising:
a buffer layer;
a first electrode formed on the buffer layer;
a second electrode formed with a lift-off process; and
a layer of piezoelectric material sandwiched between said first and second electrodes.
18 . The acoustical resonator of claim 17 wherein said first electrode comprises molybdenum.
19 . The acoustical resonator of claim 17 wherein said layer of piezoelectric material comprises AlN.
20 . The acoustical resonator of claim 17 further comprising a substrate having a cavity in a surface thereof, said first electrode bridging said cavity.