FBAR filter with trap rich layer
View Patent ↗An acoustic resonator forms a component of an FBAR filter that includes a trap-rich layer to avoid parasitic conduction by degrading carrier lifetimes of a free charge carriers. The acoustic resonator has a first electrode, a second electrode disposed parallel to the first planar portion and a piezoelectric layer disposed between and contacting both the first and second planar electrodes. A silicon-based a support layer is bonded to the second electrode and includes a trap region. The acoustic resonator may be manufactured by (a) depositing the trap region on the support layer; (b) oxidizing a surface of the trap region; (c) depositing a bonding layer on the oxidized surface of the trap region; (d) bonding a first electrode to the bonding layer; (e) contacting a first side of a piezoelectric layer to the electrode; and (f) contacting a second side of the piezoelectric layer a second electrode.
1. An acoustic resonator, comprising:
a first electrode having a first planar portion;
a second electrode having a second planar portion disposed parallel to the first planar portion;
a piezoelectric layer disposed between and contacting both the first planar portion and the second planar portion;
a support layer bonded to the second electrode, the support layer having a trap-rich layer that degrades a carrier lifetimes of a free charge carrier; and
a silicon dioxide insulating layer interposed between the trap-rich layer and both the first electrode and the second electrode.
2. The acoustic resonator of claim 1 wherein the trap-rich layer is selected from the group consisting of amorphous silicon and polycrystalline silicon.
3. The acoustic resonator of claim 2 wherein the trap-rich layer has a thickness of from 500 nanometers (nm) and 800 nm.
4. An organic based wafer level package that includes an acoustic resonator, comprising:
the acoustic resonator having:
a first electrode having a first planar portion;
a second electrode having a second planar portion disposed parallel to the first planar portion;
a piezoelectric layer disposed between and contacting both the first planar portion and the second planar portion; and
a support layer bonded to the second electrode, the support layer having a trap-rich layer that degrades a carrier lifetimes of a free charge carrier;
an organic wall contacting the first side of the piezoelectric layer with a first wall via extending through the organic wall and contacting the first electrode and a second wall via extending through the organic wall and contacting the second electrode;
an organic roof having first and second opposing sides with the first side bonded to the organic wall with a first roof via aligned with the first wall via and a second roof via aligned with the second wall via, wherein a combination of the organic wall, the organic roof and the first planar portion define a first acoustic gap;
a silicon handle contacting the second side of the piezoelectric layer; and
a silicon wafer cap bonded to the silicon handle, wherein a combination of the silicon handle, the silicon wafer cap and the second planar portion define a second acoustic gap.
5. The acoustic resonator of claim 4 wherein the trap-rich layer is selected from the group consisting of amorphous silicon and polycrystalline silicon.
6. The acoustic resonator of claim 5 wherein the trap-rich layer has a thickness of from 500 nanometers (nm) and 800 nm.
7. The acoustic resonator of claim 6 wherein a silicon dioxide insulating layer is interposed between the trap-rich layer and both the first electrode and the second electrode.