Dual-mode MEMS resonator, oscillator, sensor, timing device, acoustic filter and front-end module and the methods of making

1. A device comprising:

a dual-mode resonator comprising:

a semiconductor substrate;

a material on the semiconductor substrate, having a cavity formed therein;

a seed layer over the cavity in a V-shape, wherein sides of the V-shape form an angle of 15 to 25 degrees with a horizontal line;

a bottom electrode on the seed layer;

an acoustic layer on the bottom electrode;

a top electrode on the acoustic layer; and

a mass loading layer on the top electrode; and

a cap over the dual-mode resonator.

2. The device according to claim 1 , further comprising the top and bottom electrodes and the mass loading layer being formed of metal and the acoustic layer being formed of a piezoelectric material.

3. The device according to claim 1 , further comprising contact vias between the top and bottom electrodes.

4. The device according to claim 1 , wherein the substrate comprises an RF semiconductor-on-insulator wafer with integrated circuits (ICs).

5. The device according to claim 4 , further comprising two transconductance transistor amplifiers on the substrate and connected to the dual mode resonator, forming a monolithic dual MEMS oscillator.

6. The device according to claim 5 , comprising:

a first oscillator using a first mode of the dual mode resonator and a first of the two amplifiers;

a second oscillator using a second mode of the resonator and a second of the two amplifiers;

a frequency multiplier that up-converts an oscillation signal of the first or the second oscillator;

a mixer that multiplies both oscillation signals;

a low-pass filter that keeps a low-frequency beat frequency product of the mixer, wherein a temperature coefficient of frequency (TCF) of the beat frequency is higher than a TCF of each of the oscillation signals; and

a sensing circuit that creates a signal proportional to a temperature change of the beat frequency signal.

7. The device according to claim 5 , further comprising:

a reference oscillator using a longitudinal mode of the dual mode resonator and a first of the two amplifiers;

a temperature sensor oscillator using a shear mode of the resonator and a second of the two amplifiers;

a programmable temperature compensation circuit that uses an oscillation signal of the temperature sensor oscillator; and

a fractional N-frequency synthesize circuit, wherein an oscillation signal of the reference oscillator and the temperature compensation circuit control the fractional N-frequency synthesize circuit.

8. The device according to claim 1 , further comprising an acoustic mirror or Bragg reflector on the grooved area under the seed layer.

9. The device according to claim 1 , further comprising:

additional dual-mode resonators on the semiconductor substrate in a ladder or lattice configuration; and

the dual-mode resonator and the additional dual-mode resonators electrically connected in series and one or more shunt resonators having different frequencies from the resonators connected in series, forming a dual-band acoustic filter.

10. The device according to claim 9 , further comprising:

a low noise amplifier (LNA) on the semiconductor substrate;

the dual band acoustic filter and the LNA;

a passive network on the substrate for separating the two bands of the dual-band acoustic filter;

the LNA and the passive network;

forming a single-pole dual-throw (SPDT) switch on the substrate for alternately selecting one of the two bands; and

connecting the passive network and the SPDT switch, forming an RF front-end module.

11. A device comprising:

a dual-mode resonator comprising:

a semiconductor substrate;

a material on the semiconductor substrate, the material having a V-shaped groove, forming a grooved area, with sides of the V-shaped groove forming an angle of 15 to 25 degrees with a horizontal line;

an acoustic mirror or Bragg reflector on the grooved area;

a seed layer over the acoustic mirror or Bragg reflector;

a bottom electrode on the seed layer;

an acoustic layer on the bottom electrode;

a top electrode on the acoustic layer; and

a mass loading layer on the top electrode; and

a cap over the dual-mode resonator.

12. A method comprising:

forming a material on a semiconductor substrate;

forming a V-shaped groove in the material, forming a grooved area, sides of the V-shaped groove forming an angle of 15 to 25 degrees with a horizontal line;

forming a seed layer on the grooved area;

forming a bottom electrode on the seed layer on at least the grooved area;

forming an acoustic layer on the bottom electrode on at least the grooved area;

forming a top electrode on the acoustic layer on at least the grooved area;

forming a mass loading layer on the top electrode on at least the grooved area;

forming release vias through the top electrode, the acoustic layer, the bottom electrode, and the seed layer;

removing at least a portion of the material through the release vias, forming a dual-mode resonator; and

forming a cap over the dual-mode resonator.

13. The method according to claim 12 , further comprising forming the groove by:

forming photoresist portions on the material;

baking the photoresist portions, forming a separation between the photoresist portions;

dry etching the material through the photoresist portions until the photoresist is removed and the angle of 15 to 25 degrees is reached.

14. The method according to claim 12 , comprising forming the top and bottom electrodes and the mass loading layer of metal and the acoustic layer of a piezoelectric material.

15. The method according to claim 12 , comprising forming contact vias between the top and bottom electrodes prior to forming the release vias.

16. The method according to claim 15 , comprising removing the material by dry etching.

17. The method according to claim 12 , further comprising forming a dielectric interposer layer on the semiconductor substrate prior to forming the material, wherein the substrate comprises an RF semiconductor-on-insulator wafer with integrated circuits (ICs).

18. The method according to claim 17 , further comprising:

forming two transconductance transistor amplifiers on the substrate; and

connecting the two amplifiers to the dual mode resonator, forming a monolithic dual MEMS oscillator.

19. The method according to claim 18 , comprising:

forming a first oscillator using a first mode of the dual mode resonator and a first of the two amplifiers;

forming a second oscillator using a second mode of the resonator and a second of the two amplifiers;

forming a frequency multiplier that up-converts an oscillation signal of the first or the second oscillator;

forming a mixer that multiplies both oscillation signals;

forming a low-pass filter that keeps a low-frequency beat frequency product of the mixer, wherein a temperature coefficient of frequency (TCF) of the beat frequency is higher than a TCF of each of the oscillation signals;

forming a sensing circuit that creates a signal proportional to a temperature change of the beat frequency signal.

20. The method according to claim 18 , further comprising:

forming a reference oscillator using a longitudinal mode of the dual mode resonator and a first of the two amplifiers;

forming a temperature sensor oscillator using a shear mode of the resonator and a second of the two amplifiers;

forming a programmable temperature compensation circuit that uses an oscillation signal of the temperature sensor oscillator; and

forming a fractional N-frequency synthesize circuit, wherein an oscillation signal of the reference oscillator and the temperature compensation circuit control the fractional N-frequency synthesize circuit.

21. The method according to claim 12 , further comprising forming an acoustic mirror or Bragg reflector on the grooved area prior to forming the seed layer.

22. The method according to claim 12 , further comprising:

forming additional dual-mode resonators on the semiconductor substrate in a ladder or lattice configuration;

electrically connecting the dual-mode resonator and the additional dual-mode resonators in series and connecting one or more shunt resonators having different frequencies from the resonators connected in series, forming a dual-band acoustic filter.

23. The method according to claim 22 , further comprising:

forming a low noise amplifier (LNA) on the semiconductor substrate;

connecting the dual band acoustic filter and the LNA

forming a passive network on the substrate for separating the two bands of the dual-band acoustic filter;

connecting the LNA and the passive network;

forming a single-pole dual-throw (SPDT) switch on the substrate for alternately selecting one of the two bands; and

connecting the passive network and the SPDT switch, forming an RF front-end module.

24. A method comprising:

forming a material on a semiconductor substrate;

forming a V-shaped groove in the material, forming a grooved area, sides of the V-shaped groove forming an angle of 15 to 25 degrees with a horizontal line;

forming an acoustic mirror or Bragg reflector on the grooved area:

forming a seed layer on the acoustic mirror or Bragg reflector;

forming a bottom electrode on the seed layer;

forming an acoustic layer on the bottom electrode;

forming a top electrode on the acoustic layer;

forming a mass loading layer on the top electrode, forming a dual-mode resonator; and

forming a cap over the dual-mode resonator.