Micro-transfer-printed acoustic wave filter device
A compound acoustic wave filter device comprises a support substrate having an including two or more circuit connection pads. An acoustic wave filter includes a piezoelectric filter element and two or more electrodes. The acoustic wave filter is micro-transfer printed onto the support substrate. An electrical conductor electrically connects one or more of the circuit connection pads to one or more of the electrodes.
1. An acoustic wave filter source wafer, comprising:
a source wafer of substrate material;
a patterned sacrificial layer forming sacrificial portions on, over, or in the substrate material, a surface of the substrate material, the source wafer, or a surface of the source wafer, the sacrificial portions defining separate anchors between the sacrificial portions; and
a piezoelectric acoustic wave filter formed entirely over each sacrificial portion, the piezoelectric acoustic wave filter comprising (i) a layer of piezoelectric material and (ii) two or more electrodes in or on the piezoelectric material,
wherein a portion of the piezoelectric acoustic wave filter in contact with the sacrificial portion is chemically and selectively etch-resistant so that the contact portion has a chemical selectivity different from the patterned sacrificial layer and wherein the piezoelectric acoustic wave filter is attached to at least one of the separate anchors with at least one respective fracturable tether.
2. The acoustic wave filter source wafer of claim 1 , wherein the contact portion is a portion of the layer of piezoelectric material or all of or a portion of an electrode.
3. The acoustic wave filter source wafer of claim 1 , comprising one or more acoustic mirrors, each acoustic mirror disposed on a side of an electrode opposite the layer of piezoelectric material, and wherein the contact portion is an acoustic mirror.
4. The acoustic wave filter source wafer of claim 1 , wherein the patterned sacrificial layer is a patterned layer of etchable material that can be removed to form a gap between the etch-resistant piezoelectric acoustic wave filter contact portion structure and the substrate material.
5. The acoustic wave filter source wafer of claim 1 , wherein the two or more electrodes are formed on opposite sides of the piezoelectric acoustic wave filter and the piezoelectric acoustic wave filter is a bulk acoustic wave filter.
6. The acoustic wave filter source wafer of claim 1 , wherein the piezoelectric acoustic wave filter has a width from 2 to 5 μm, 5 to 10 μm, 10 to 20 μm, or 20 to 50 μm, has a length from 2 to 5 μm, 5 to 10 μm, 10 to 20 μm, or 20 to 50 μm, or has a height from 2 to 5 μm, 4 to 10 μm, 10 to 20 μm, or 20 to 50 μm.
7. The acoustic wave filter source wafer of claim 1 , wherein the piezoelectric acoustic wave filter is attached to the source wafer by only one fracturable tether.
8. An acoustic wave filter source wafer, comprising:
a source wafer of substrate material;
a patterned sacrificial layer forming sacrificial portions on, over, or in the substrate material, a surface of the substrate material, the source wafer, or a surface of the source wafer, the sacrificial portions defining separate anchors between the sacrificial portions; and
a piezoelectric acoustic wave filter formed entirely over each sacrificial portion, the piezoelectric acoustic wave filter comprising (i) a layer of piezoelectric material and (ii) two or more electrodes in or on the piezoelectric material,
wherein a portion of the piezoelectric acoustic wave filter in contact with the sacrificial portion is chemically and selectively etch-resistant so that the contact portion has a chemical selectivity different from the patterned sacrificial layer and wherein the piezoelectric acoustic wave filter is attached to at least one of the separate anchors with at least one respective fracturable tether,
wherein the two or more electrodes are formed on a common side of the piezoelectric acoustic wave filter and the piezoelectric acoustic wave filter is a surface acoustic wave filter.
9. An acoustic wave filter source wafer, comprising:
a source wafer;
a plurality of piezoelectric acoustic wave filters each suspended over a respective gap by a respective fracturable tether connected to the source wafer, the piezoelectric acoustic wave filter comprising (i) a layer of piezoelectric material and (ii) two or more electrodes in or on the piezoelectric material.
10. The acoustic wave filter source wafer of claim 9 , wherein each of the plurality of piezoelectric acoustic wave filters is suspended over the respective gap by only the respective fracturable tether.