Acoustic resonator performance enhancement using selective metal etch

• US 8,188,810 B2
• Filed: 07/19/2010
• Issued: 05/29/2012
• Est. Priority Date: 12/22/2004
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies Wireless IP Singapore Pte Limited (Broadcom, Inc.)
• Inventors: Fazzio, Ronald S., Feng, Hongjun
• Primary Examiner(s): Summons, Barbara
• Application Number:
  US12/838,657
• Publication Number:
  US 20100277257A1
• Time in Patent Office: 680 Days
• Field of Search: 333187-192, 310/312, 310/322, 310/324, 310/326, 310/335
• US Class Current: 333/187
• CPC Class Codes: H03H 9/02118 of lateral leakage between adjacent resonators
• CPC Class Codes: H03H 9/173 Air-gaps

Abstract

An acoustic resonator comprises: a substrate; a first electrode adjacent the substrate; a layer of piezoelectric material adjacent the first electrode; a second electrode adjacent the layer of piezoelectric material; and a passivation layer adjacent the layer of piezoelectric material. The passivation layer includes a recessed feature. Fill material is provided in the recessed feature of the passivation layer.

Claims

1. An acoustic resonator comprising:

a substrate;

a first electrode adjacent the substrate;

a layer of piezoelectric material adjacent the first electrode;

a second electrode adjacent the layer of piezoelectric material;

a passivation layer adjacent the second electrode, wherein the passivation layer includes a recessed feature; and

fill material in the recessed feature of the passivation layer, wherein the fill material is not electrically connected to the acoustic resonator.

2. The acoustic resonator of claim 1 wherein the second electrode comprises a material that is the same as the fill material in the recessed feature.

3. The acoustic resonator of claim 1 wherein the fill material is a material selected from the group comprising dielectrics, metals, piezoelectrics, Mo, Pt, Al, Cu, W, Au, Ag, polyimide, BCB (benzocyclobutene), SiO₂, Si₃N₄, AlN, ZnO, LiNbO₃, PZT, LiTaO₃, or Al₂O₃.

4. The acoustic resonator of claim 1 wherein the recessed feature has a depth in the passivation layer that is on the order of ten to thousands of angstroms and a width on the order of fractions of a micron to microns.

5. An acoustic resonator comprising:

a substrate;

a first electrode adjacent the substrate;

a layer of piezoelectric material adjacent the first electrode;

a second electrode adjacent the layer of piezoelectric material;

a passivation layer adjacent the second electrode, wherein the passivation layer includes a recessed feature; and

fill material in the recessed feature of the passivation layer, wherein the recessed feature extends around a substantial portion of the perimeter of the passivation layer.

6. The acoustic resonator of claim 5, wherein the second electrode comprises a material that is the same as the fill material in the recessed feature.

7. The acoustic resonator of claim 5, wherein the fill material is a material selected from the group comprising dielectrics, metals, piezoelectrics, Mo, Pt, Al, Cu, W, Au, Ag, polyimide, BCB (benzocyclobutene), SiO₂, Si₃N₄, AlN, ZnO, LiNbO₃, PZT, LiTaO₃, or Al₂O₃.

8. The acoustic resonator of claim 5, wherein the recessed feature has a depth in the passivation layer that is on the order of ten to thousands of angstroms and a width on the order of fractions of a micron to microns.