# US 11,444,599 B2 · Suppression of spurious signals in surface acoustic wave devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,444,599 B2 - Document ID: US11444599B2 - Status: Granted - Kind: B2 - Application number: 17/001,843 - Filed: 2020-08-25 - Published: 2021-03-04 - Granted: 2022-09-13 - Earliest claimed: 2019-08-29 - Assignees: Skyworks Solutions, Inc. - Applicants: Skyworks Solutions, Inc. - Inventors: Riho Sasaki; Joji Fujiwara - Web page: https://patentgrep.com/patent/US11444599B2 ## CPC - H03H 9/1457: {Transducers having different finger widths} - H03H 9/02543: {Characteristics of substrate, e.g. cutting angles} - H03H 9/02858: {of wave front distortion} - H03H 9/02881: {of diffraction of wave beam} - H03H 9/13: for networks consisting of piezoelectric or electrostrictive materials (for networks using surface acoustic waves H03H9/145) - H03H 9/14541: {Multilayer finger or busbar electrode} - H03H 9/25: Constructional features of resonators using surface acoustic waves {(devices for manipulating acoustic surface waves in general G10K11/36)} - H03H 9/6483: {Ladder SAW filters} - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) ## Abstract An acoustic wave device comprises a substrate including a piezoelectric material, interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate. The IDT electrodes having gap regions, edge regions, and center regions. A duty factor of the IDT electrodes in the edge regions is greater than the duty factor of the IDT electrodes in the center regions. A first dielectric film is disposed above the IDT electrodes and an upper surface of the substrate. The first dielectric film has a greater thickness in portions of the center regions than in portions proximate the gap regions. ## Claims ### Claim 1 An acoustic wave device comprising: a substrate including a piezoelectric material; interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate, the IDT electrodes having gap regions, edge regions, and center regions, a duty factor of the IDT electrodes in the edge regions being greater than a duty factor of the IDT electrodes in the center regions; a first dielectric film disposed above the IDT electrodes and an upper surface of the substrate, the first dielectric film having a greater thickness in portions of the center regions than in portions proximate the gap regions; and a second dielectric film disposed between the first dielectric film and the IDT electrodes, the second dielectric film exhibiting a lower acoustic velocity than the first dielectric film. ### Claim 2 (depends on 1) The acoustic wave device of claim 1 wherein a velocity of an acoustic wave in the center regions is greater than the velocity of the acoustic wave in the edge regions. ### Claim 3 (depends on 1) The acoustic wave device of claim 1 wherein the first dielectric film has a greater thickness in the center regions and portions of the edge regions proximate the center regions than in portions of the edge regions distal to the center regions. ### Claim 4 (depends on 3) The acoustic wave device of claim 3 wherein lengths of the portions of the edge regions proximate the center regions are less than lengths of the portions of the edge regions distal to the center regions. ### Claim 5 (depends on 3) The acoustic wave device of claim 3 wherein lengths of the portions of the edge regions proximate the center regions are at least as long as lengths of the portions of the edge regions distal to the center regions. ### Claim 6 (depends on 1) The acoustic wave device of claim 1 wherein the IDT electrodes include a layer of tungsten. ### Claim 7 (depends on 1) The acoustic wave device of claim 1 further comprising strips of a material having a density higher than the density of the second dielectric film disposed in the second dielectric film in the edge regions. ### Claim 8 (depends on 1) The acoustic wave device of claim 1 wherein widths of the IDT electrodes in the gap regions is less than widths of the IDT electrodes in the center regions. ### Claim 9 (depends on 1) The acoustic wave device of claim 1 further comprising dummy IDT electrodes disposed in the gap regions. ### Claim 10 (depends on 9) The acoustic wave device of claim 9 wherein a duty factor of the dummy IDT electrodes is different from the duty factor of the IDT electrodes in the center regions and different from the duty factor of the IDT electrodes in the edge regions. ### Claim 11 (depends on 10) The acoustic wave device of claim 10 wherein the duty factor of the dummy IDT electrodes is less than the duty factor of the IDT electrodes in the center regions and less than the duty factor of the IDT electrodes in the edge regions. ### Claim 12 An acoustic wave device comprising: a substrate including a piezoelectric material; interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate, the IDT electrodes having gap regions, edge regions, and center regions, a width of the IDT electrodes in the gap regions being less than a width of the IDT electrodes in the center regions; and dummy IDT electrodes disposed in the gap regions. ### Claim 13 (depends on 12) The acoustic wave device of claim 12 wherein a duty factor of the IDT electrodes in the edge regions is greater than a duty factor of the IDT electrodes in the center regions. ### Claim 14 (depends on 12) The acoustic wave device of claim 12 wherein a duty factor of the dummy IDT electrodes is different from the duty factor of the IDT electrodes in the center regions and different from a duty factor of the IDT electrodes in the edge regions. ### Claim 15 (depends on 14) The acoustic wave device of claim 14 wherein the duty factor of the dummy IDT electrodes is less than the duty factor of the IDT electrodes in the center regions and less than the duty factor of the IDT electrodes in the edge regions. ### Claim 16 An acoustic wave device comprising: a substrate including a piezoelectric material; interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate, the IDT electrodes having gap regions, edge regions, and center regions, a duty factor of the IDT electrodes in the edge regions being greater than a duty factor of the IDT electrodes in the center regions; and a first dielectric film disposed above the IDT electrodes and an upper surface of the substrate, the first dielectric film having a greater thickness in portions of the center regions than in portions proximate the gap regions, the first dielectric film having a greater thickness in the center regions and portions of the edge regions proximate the center regions than in portions of the edge regions distal to the center regions, lengths of the portions of the edge regions proximate the center regions being at least as long as lengths of the portions of the edge regions distal to the center regions. ### Claim 17 An acoustic wave device comprising: a substrate including a piezoelectric material; interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate, the IDT electrodes having gap regions, edge regions, and center regions, a duty factor of the IDT electrodes in the edge regions being greater than a duty factor of the IDT electrodes in the center regions, widths of the IDT electrodes in the gap regions being less than the widths of the IDT electrodes in the center regions; a first dielectric film disposed above the IDT electrodes and an upper surface of the substrate, the first dielectric film having a greater thickness in portions of the center regions than in portions proximate the gap regions. ### Claim 18 An acoustic wave device comprising: a substrate including a piezoelectric material; interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate, the IDT electrodes having gap regions, edge regions, and center regions, a duty factor of the IDT electrodes in the edge regions being greater than a duty factor of the IDT electrodes in the center regions; a first dielectric film disposed above the IDT electrodes and an upper surface of the substrate, the first dielectric film having a greater thickness in portions of the center regions than in portions proximate the gap regions; and dummy IDT electrodes disposed in the gap regions, a duty factor of the dummy IDT electrodes being different from the duty factor of the IDT electrodes in the center regions and different from the duty factor of the IDT electrodes in the edge regions. ### Claim 19 An acoustic wave device comprising: a substrate including a piezoelectric material; interdigital transducer (IDT) electrodes disposed on an upper surface of the substrate, the IDT electrodes having gap regions, edge regions, and center regions, a duty factor of the IDT electrodes in the edge regions being greater than a duty factor of the IDT electrodes in the center regions; and a first dielectric film disposed above the IDT electrodes and an upper surface of the substrate, the first dielectric film having a greater thickness in portions of the center regions than in portions proximate the gap regions, the first dielectric film having a greater thickness in the center regions and portions of the edge regions proximate the center regions than in portions of the edge regions distal to the center regions, lengths of the portions of the edge regions proximate the center regions being less than lengths of the portions of the edge regions distal to the center regions.