Micro-electro-mechanical resonators
View Patent ↗A tunable non-reciprocal frequency limiter with an asymmetric micro-electro-mechanical resonator has two independent transducer ports. One port has a film stack including a 10 nm hafnium zirconium oxide (HZO) and another port has a film stack including a 120 nm aluminum nitride (AlN) film. These film stacks are deposited on top of 70 nm single crystal silicon substrate applying CMOS compatible fabrication techniques. The asymmetric transducer architecture with dissimilar electromechanical coupling coefficients force the resonator into mechanical nonlinearity on actuation with transducer having larger coupling. A proof-of-concept electrically-coupled channel filter is demonstrated with two such asymmetric resonators at ˜253 MHz with individual Q res of ˜870 and a non-reciprocal transmission ratio (NTR) ˜16 dB and BW 3 dB of 0.25%.
1. A two-port frequency limiter, comprising:
a substrate;
a first aluminum nitride (AlN) layer disposed on the substrate;
a first molybdenum (Mo) layer disposed on the first AlN layer;
a first transducer formed on the first Mo layer, wherein the first transducer comprises:
a second AlN layer disposed on the first Mo layer, and
a second Mo layer disposed on the second AlN layer; and
a second transducer formed on the second Mo layer located in a vicinity of the first transducer, wherein the second transducer comprises:
a hafnium zirconium oxide (HZO) layer deposited on the second Mo layer,
a titanium nitride (TiN) layer on top of the HZO layer, and
a first conductive layer disposed on the TiN layer.
2. The two-port frequency limiter according to claim 1 , wherein the HZO layer is deposited by Atomic Layer Deposition techniques.
3. The two-port frequency limiter according to claim 1 , wherein the HZO layer has a thickness ranging from 5 nm to 25 nm.
4. The two-port frequency limiter according to claim 1 , wherein the titanium nitrite (TiN) layer is disposed between the HZO layer and the first conductive layer.
5. The two-port frequency limiter according to claim 1 , wherein the first conductive layer comprises one of platinum (Pt), aluminum (Al), gold (Au), and silver (Ag).
6. The two-port frequency limiter according to claim 1 , wherein the first AlN layer is a seed layer and the second AlN layer is a crystalline layer.
7. The two-port frequency limiter according to claim 1 , wherein the substrate has a crystal silicon surface.
8. The two-port frequency limiter according to claim 1 , wherein the second AlN layer is a crystalline layer and has a thickness ranging from 50 nm to 200 nm.
9. A two-port frequency limiter, comprising:
a substrate;
a first transducer, wherein the first transducer comprises:
a first conductive layer,
a first piezoelectric layer, and
a second conductive layer;
and
a second transducer located in a vicinity of the first transducer, wherein the second transducer comprises:
a second piezoelectric layer disposed directly on the second conductive layer, and
a third conductive layer disposed on the second piezoelectric layer, wherein:
the second piezoelectric layer comprises a HZO layer and a TiN layer on top of the HZO layer.
10. The two-port frequency limiter according to claim 9 , wherein the first piezoelectric layer comprises one of an AlN layer, a HZO layer, a Lead Zirconate Titanate (PZT) layer, a Zinc Oxide layer (ZnO), and a Lithium Niobate (LiNbO3) layer.
11. The two-port frequency limiter according to claim 10 , wherein the HZO layer in the first piezoelectric layer is formed by Atomic Layer Deposition techniques.
12. The two-port frequency limiter according to claim 11 , wherein the HZO layer has a thickness ranging from 5 nm to 25 nm.
13. The two-port frequency limiter according to claim 9 , wherein the HZO layer in the second piezoelectric layer is formed by Atomic Layer Deposition techniques.
14. The two-port frequency limiter according to claim 9 , wherein the HZO layer has a thickness ranging from 5 nm to 25 nm.
15. The two-port frequency limiter according to claim 9 , wherein the first conductive layer comprises one of Mo, platinum (Pt), aluminum (Al), gold (Au), and Silver (Ag).
16. The two-port frequency limiter according to claim 9 , wherein the second conductive layer comprises one of Mo, platinum (Pt), aluminum (Al), gold (Au), and Silver (Ag).
17. The two-port frequency limiter according to claim 9 , wherein the third conductive layer comprises but not limited to one of Mo, platinum (Pt), aluminum (Al), gold (Au), Silver (Ag).
18. The two-port frequency limiter according to claim 9 , wherein an electromechanical coupling coefficient of the second transducer is different from an electromechanical coupling coefficient of the first transducer.