High density multi-poled thin film piezoelectric devices and methods of making the same
Disclosed are multi-poled piezoelectric devices with improved packing density and methods for making such multi-poled piezoelectric devices with improved packing density. The multi-poled piezoelectric devices comprise: a) a top electrode, a piezoelectric layer, and a bottom electrode fabricated on a substrate; b) vias generated by etching the piezoelectric layer, the top electrode, or both; and c) a re-distribution layer (RDL) deposited over one or more of: the top electrode, the piezoelectric layer, the bottom electrode, or the one or more vias.
1. A multi-poled piezoelectric device, the multi-poled piezoelectric device comprising:
a) a top electrode, a piezoelectric layer, and a bottom electrode fabricated on a substrate;
b) a first vertical interconnect access (via) generated by etching the piezoelectric layer and the top electrode;
c) a second vertical interconnect access (via) generated by etching the piezoelectric layer, the top electrode, and the bottom electrode; and
d) a re-distribution layer (RDL) deposited over one or more of: the top electrode, the piezoelectric layer, the bottom electrode, or the one or more vias.
2. The multi-poled piezoelectric device of claim 1 , wherein the one or more vias comprises: a pre-determined depth in the piezoelectric layer etched by a first method; a second depth continuing from the pre-determined depth in the piezoelectric layer etched by a second method to stop at a top surface of the bottom electrode.
3. The multi-poled piezoelectric device of claim 1 , wherein the piezoelectric layer comprises a stepped profile along a vertical direction configured to mitigate issues in topography of the one or more vias.
4. The multi-poled piezoelectric device of claim 2 , wherein the pre-determined depth is less than a full depth of the piezoelectric layer along a vertical direction.
5. The multi-poled piezoelectric device of claim 1 , wherein the RDL comprises a RDL dielectric layer and a RDL conductor layer thereabove.
6. The multi-poled piezoelectric device of claim 1 , wherein one or more of the top electrode, the piezoelectric layer, or the bottom electrode is generated from etching a first piezoelectric device.
7. The multi-poled piezoelectric device of claim 2 , wherein the first method is an isotropic etch or a wet etch and the second method is an anisotropic etch or a dry etch.
8. The multi-poled piezoelectric device of claim 2 , wherein the first method is an anisotropic etch or a dry etch and the second method is an isotropic etch or a wet etch.
9. The multi-poled piezoelectric device of claim 5 , wherein the RDL dielectric layer is patterned and etched using a lift-off process and the RDL conductor layer is deposited and patterned using a lift-off process.
10. The multi-poled piezoelectric device of claim 5 , wherein one or both of the RDL dielectric layer and the RDL conductor layer is etched.
11. The multi-poled piezoelectric device of claim 6 , wherein the first piezoelectric device comprises a first bottom electrode, a first piezoelectric layer, a first top electrode, and a first substrate.
12. The multi-poled piezoelectric device of claim 6 , wherein the first piezoelectric device is uni-poled.
13. The multi-poled piezoelectric device of claim 6 , wherein the first piezoelectric device is multi-poled.
14. The multi-poled piezoelectric device of claim 6 , wherein the multi-poled piezoelectric device or the first piezoelectric device is at least part of a piezoelectric micromachined ultrasonic transducer (pMUT).
15. A multi-poled piezoelectric device, the multi-poled piezoelectric device comprising:
a first piezoelectric device comprising:
a first bottom electrode;
a first piezoelectric layer;
a first top electrode; and
a first substrate;
one or more of the first bottom electrode, the first piezoelectric layer, or the first top electrode being etched to separate the first piezoelectric device into a plurality of piezoelectric devices;
one or more first vertical interconnect access (vias) created from etching the first piezoelectric layer and the first top electrode;
one or more second vertical interconnect access (vias) created from etching the piezoelectric layer, the top electrode, and the bottom electrode; and
a re-distribution layer (RDL) over the first piezoelectric device, the one or more vias, or both.
16. The multi-poled piezoelectric device of claim 15 , wherein the first top electrode is etched to create a plurality of top electrodes.
17. The multi-poled piezoelectric device of claim 16 , wherein the first piezoelectric layer is etched to generate a plurality of piezoelectric layers.
18. The multi-poled piezoelectric device of claim 17 , wherein the first bottom electrode is etched to generate a plurality of bottom electrodes.
19. The multi-poled piezoelectric device of claim 15 , wherein the RDL comprises a RDL dielectric layer deposited over the first piezoelectric device and a RDL conductor layer deposited over the RDL dielectric layer.