Resonator and component with hermetic encapsulation

• US 20060164186A1
• Filed: 06/23/2003
• Published: 07/27/2006
• Est. Priority Date: 08/27/2002
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Epcos AG (TDK Corporation)
• Inventors: Heinze, Habbo, Stoemmer, Ralph
• Granted Patent: US 7,385,467 B2
• Time in Patent Office: Days
• US Class Current: 333/189
• CPC Class Codes: H03H 9/0542 consisting of a lateral arrangement H03H9/0566 takes precedence
• CPC Class Codes: H03H 9/1007 for bulk acoustic wave [BAW] devices
• CPC Class Codes: H03H 9/172 Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
• CPC Class Codes: H03H 9/175 Acoustic mirrors
• CPC Class Codes: H03H 9/586 Means for mounting to a substrate, i.e. means constituting the material interface confining the waves to a volume
• CPC Class Codes: H03H 9/589 Acoustic mirrors

Abstract

Proposed is a resonator which works with bulk acoustic waves and is based on a layer structure known in the art, which is arranged over a substrate. According to the invention, the total surface of the layer structure, including all resonators contained therein, is covered with a dielectric layer and a metal layer which together form an acoustic mirror, a low-k dielectric being used for the dielectric layer. The total-surface mirror offers broadband functionality over a suitable frequency range. The dielectric contained within the mirror acts as a sealing protective layer for the resonator or resonators.

Claims

1. A resonator for use with bulk acoustic waves, the resonator comprising:

a wafer;

a layer structure above the wafer;

a dielectric layer above the layer structure, the dielectric layer comprising a hermetic encapsulation for the resonator, the dielectric layer comprising a material and having a thickness that result in a first acoustic impedance; and

a metal layer above the dielectric layer, the metal layer comprising a material and having a thickness that result in a second acoustic impedance, the second acoustic impedance being higher than the first acoustic impedance, the metal layer and the dielectric layer being parts of an acoustic mirror for bulk acoustic waves in the resonator;

wherein the layer structure comprises;

first and second electrode layers that comprise electrodes for the resonator; and

at least one piezoelectric layer that is between the first and second electrode layers.

2. The resonator of claim 1, wherein thicknesses of the dielectric layer and the metal layer are in a range of a quarter wavelength of the bulk acoustic waves or in a range of an odd multiple of the quarter wavelength.

3. The resonator of claim 1 wherein the acoustic mirror comprises at least one other layer pair arranged above the metal layer, the at least one other layer pair consisting comprising a layer of relatively low acoustic impedance and a layer of relatively high acoustic impedance.

18. The resonator of claim 1, wherein the dielectric material comprises a low-k dielectric comprising at least one of an aerogel, a porous silicate, an organosilicate, a siloxane derived from condensed silsesquioxanes, a polyaromatic compound, a cross-linked polyphenylene, and a polymerized benzocyclobutene

19. The resonator of claim 1, wherein the metal layer comprises at least one of tungsten W, molybdenum Mo, gold Au or aluminum nitride AlN.

20. The resonator of claim 1, wherein the wafer has a surface comprising solderable contacts that are electrically connected to the resonator or to one or more of a plurality of active and/or passive components.

4. A component comprising:

a plurality of resonators that are electrically interconnected by electrode layers to form at least a portion of a circuit;

wherein the plurality of resonators comprise;

a wafer

layer structures on the wafer;

a dielectric layer above the layer structures, the dielectric layer comprising a hermetic encapsulation for the plurality of resonators, the dielectric layer comprising a material and having a thickness that result in a first acoustic impedance; and

a metal layer above the dielectric layer, the metal layer comprising a material and having a thickness that result in a second acoustic impedance, the second acoustic impedance being higher than the first acoustic impedance, the metal layer and the dielectric layer being parts of an acoustic mirror,

wherein each of the layer structures comprises first and second electrode layers that comprise electrodes, and at least one piezoelectric layer that is between the first and second electrode layers.

5. The component of claim 4, wherein the dielectric layer comprises an organic layer.

6. The component of claim 5, wherein the dielectric layer comprises benzocyclobutenes.

7. The component of claim 4, wherein the dielectric layer is over substantially an entire surface of the wafer and over the plurality of resonators, a top surface of the dielectric layer being substantially planar such that thicknesses of the dielectric layer needed to implement the acoustic mirror are over the plurality of resonators.

8. The component of claim 4, further comprising:

active or passive circuit elements on or within the wafer and integrated with the plurality of resonators into one or more circuits, wherein layers forming the acoustic mirror comprise an encapsulation for the active or passive circuit elements and the plurality of resonators.

9. The component of claim 8, wherein the plurality of resonators and the active or passive circuit elements comprise parts of a circuit on the wafer, the circuit comprising one or more of a high-frequency circuit, an adaptation circuit, an antenna circuit, a diode circuit, a transistor circuit, a highpass filter, a lowpass filter, a bandpass filter, a filter having a tunable frequency, a power amplifier, a preamplifier, an LNA, a diplexer, a duplexer, a multi filter, a coupler, a directional coupler, a memory element, a balun, a mixer, and an oscillator.

10. An apparatus comprising:

plural components according to claim 4.

11. The component of claim 4, wherein the dielectric material comprises a low-k dielectric.

12. The component of claim 4, wherein the metal layer comprises at least one of tungsten W, molybdenum Mo, gold Au or aluminum nitride AlN.

13. The component of claim 11, wherein the low-k dielectric comprises at least one of an aerogel, a porous silicate, an organosilicate, a siloxane derived from condensed silsesquioxanes, a polyaromatic compound, a cross-linked polyphenylene and a polymerized benzocyclobutene.

14. The component of claim 4, wherein the wafer has a surface comprising solderable contacts that are electrically connected to the plurality of resonators or to one or more of a plurality of active and/or passive components integrated with the plurality of resonators in circuits.

15. The component of claim 4, wherein the wafer has an underside that comprises solderable connecting terminals, the solderable connecting terminals being electrically connected to the plurality of resonators or to one or more of a plurality of active and/or passive components integrated in circuits with the plurality of resonators via feed-throughs in the wafer.

16. The component of claim 4, wherein the component comprises a bulk acoustic wave resonator, a stacked crystal filters, or a coupled resonator filter.

17. The component of claim 4, wherein the acoustic mirror comprises at least one other layer pair arranged above the metal layer, the at least one other layer pair comprising a layer of relatively low acoustic impedance and a layer of relatively high acoustic impedance.