# US 2014/0152152 A1 · Acoustic resonator comprising temperature compensating layer and perimeter distributed bragg reflector > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152152 A1 - Document ID: US20140152152A1 - Status: Published application - Kind: A1 - Application number: 14/092,026 - Filed: 2013-11-27 - Published: 2014-06-05 - Earliest claimed: 2011-03-29 - Assignees: Avago Technologies General IP (Singapore) Pte. Ltd. - Applicants: Avago Technologies General IP (Singapore) Pte. Ltd. - Inventors: Dariusz Burak; John Choy; Kevin J. Grannen; Phil Nikkel - Web page: https://patentgrep.com/patent/US20140152152A1 ## CPC - H03H 9/02102: {of temperature influence (cutting angles H03H9/02015)} - H03H 9/173: {Air-gaps} - H03H 9/175: {Acoustic mirrors} - H03H 9/585: {Stacked Crystal Filters [SCF]} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) ## Abstract An acoustic resonator structure includes a bottom electrode disposed on a substrate, a piezoelectric layer disposed on the bottom electrode, a top electrode disposed on the piezoelectric layer, a cavity disposed beneath the bottom electrode, and a temperature compensating feature. The temperature compensating feature has a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric and electrode layers. The acoustic resonator structure further includes an acoustic reflector disposed over the substrate around a perimeter of the cavity. The acoustic reflector includes a layer of low acoustic impedance material stacked on a layer of high acoustic impedance material. ## Claims ### Claim 1 An acoustic resonator, comprising: a bottom electrode disposed on a substrate; a piezoelectric layer disposed on the bottom electrode; a top electrode disposed on the piezoelectric layer; a temperature compensating feature having a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric layer, the bottom electrode and the top electrode; a cavity disposed beneath the bottom electrode; and an acoustic reflector disposed over the substrate around a perimeter of the cavity, the acoustic reflector comprising a layer of low acoustic impedance material stacked on a layer of high acoustic impedance material. ### Claim 2 (depends on 1) The acoustic resonator of claim 1, wherein the temperature compensating feature comprises a temperature compensating layer formed in at least one of the bottom electrode and the top electrode. ### Claim 3 (depends on 2) The acoustic resonator of claim 2, further comprising: at least one frame disposed within a main membrane region defined by an overlap between the bottom electrode, the piezoelectric layer, and the top electrode, and having an outer edge substantially aligned with a boundary of the main membrane region; and a collar formed separate from the frame, disposed outside the main membrane region, and having an inner edge substantially aligned with the boundary of or overlapping the main membrane region. ### Claim 4 (depends on 3) The acoustic resonator of claim 3, wherein the at least one frame comprises a frame disposed at a bottom portion of the top electrode, and the temperature compensating layer is formed in the bottom electrode. ### Claim 5 (depends on 4) The acoustic resonator of claim 4, wherein the at least one frame comprises another frame disposed at one of a top portion or a bottom portion of the bottom electrode. ### Claim 6 (depends on 3) The acoustic resonator of claim 3, wherein the at least one frame comprises a frame disposed at a bottom portion of the bottom electrode, and the temperature compensating layer is formed in the top electrode. ### Claim 7 (depends on 4) The acoustic resonator of claim 4, wherein the collar is formed between the acoustic reflector and the bottom electrode. ### Claim 8 (depends on 6) The acoustic resonator of claim 6, wherein the collar is formed between the acoustic reflector and the bottom electrode. ### Claim 9 (depends on 5) The acoustic resonator of claim 5, wherein the collar is formed between the acoustic reflector and the bottom electrode. ### Claim 10 (depends on 1) The acoustic resonator of claim 1, wherein the temperature compensating feature comprises a temperature compensating layer formed in the piezoelectric layer. ### Claim 11 (depends on 10) The acoustic resonator of claim 10, further comprising: at least one frame disposed within a main membrane region defined by an overlap between the bottom electrode, the piezoelectric layer, and the top electrode, and having an outer edge substantially aligned with a boundary of the main membrane region; and a collar formed separate from the frame, disposed outside the main membrane region, and having an inner edge substantially aligned with the boundary of or overlapping the main membrane region. ### Claim 12 (depends on 11) The acoustic resonator of claim 11, wherein the at least one frame comprises a first frame disposed in the bottom electrode and a second frame disposed in the top electrode. ### Claim 13 (depends on 11) The acoustic resonator of claim 11, wherein the collar is formed on a top surface of the top electrode and a planarization layer adjacent to the top electrode. ### Claim 14 (depends on 11) The acoustic resonator of claim 11, wherein the collar is formed between the bottom electrode and the piezoelectric layer. ### Claim 15 (depends on 11) The acoustic resonator of claim 11, wherein the collar is formed between the acoustic reflector and the bottom electrode. ### Claim 16 (depends on 3) The acoustic resonator of claim 3, wherein the at least one frame is an add-on frame or a composite frame. ### Claim 17 (depends on 16) The acoustic resonator of claim 16, wherein the collar comprises borosilicate glass, carbon-doped silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, zinc oxide, lead zirconium titanate, diamond or diamond-like carbon, and wherein the frame comprises a layer of copper, molybdenum, aluminum, tungsten, iridium, borosilicate glass, carbon-doped silicon oxide, silicon carbide, silicon nitride, aluminum oxide, aluminum nitride, zinc oxide, lead zirconium titanate, diamond or diamond-like carbon. ### Claim 18 (depends on 1) The acoustic resonator of claim 1, wherein the piezoelectric layer is doped with at least one rare earth element for offsetting at least a portion of degradation of an electromechanical coupling coefficient of the acoustic resonator caused by the temperature compensating feature. ### Claim 19 (depends on 3) The acoustic resonator of claim 3, wherein the collar defines a collar region having a cutoff frequency that is substantially the same as a cutoff frequency of the main membrane region. ### Claim 20 An acoustic resonator, comprising: an acoustic stack arranged over a cavity, the acoustic stack comprising a piezoelectric layer sandwiched between first and top electrode layers and having a main membrane region defined by an overlap between the bottom electrode, the piezoelectric layer, and the top electrode; a temperature compensating layer having a positive temperature coefficient for offsetting at least a portion of a negative temperature coefficient of the piezoelectric, the bottom electrode layer and the top electrode layer, the temperature compensating layer being located in one of the bottom electrode layer, the top electrode layer, and the piezoelectric layer; a distributed Bragg reflector (DBR) disposed on a substrate around a perimeter of the cavity, the DBR comprising a layer of low acoustic impedance material stacked on a layer of high acoustic impedance material; a frame disposed within the main membrane region and having an outer edge substantially aligned with a boundary of the main membrane region; and a collar disposed outside the main membrane region and having an inner edge substantially aligned with the boundary of or overlapping the main membrane region.