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US-20260128725-A1 - PIEZOELECTRIC DEVICE

US20260128725A1US 20260128725 A1US20260128725 A1US 20260128725A1US-20260128725-A1

Abstract

A piezoelectric device includes a piezoelectric layer including first and second principal surfaces opposed to each other, a support on a second principal surface side of the piezoelectric layer, a first functional electrode on at least one of the first and second principal surfaces, a substrate opposed to the first principal surface of the piezoelectric layer with a space therebetween and including a second functional electrode, and a shield between the piezoelectric layer and the substrate. The shield at least partially overlaps the first functional electrode in plan view in the first direction. A distance from a center of the shield to the piezoelectric layer is smaller than a distance from the center of the shield to the substrate.

Inventors

  • Shintaro Kubo

Assignees

  • MURATA MANUFACTURING CO., LTD.

Dates

Publication Date
20260507
Application Date
20260106
Priority Date
20230728

Claims (20)

  1. 1 . A piezoelectric device comprising: a piezoelectric layer having a thickness in a first direction and including a first principal surface and a second principal surface on an opposite side from the first principal surface; a support on a second principal surface side of the piezoelectric layer; a first functional electrode on at least one of the first principal surface and the second principal surface of the piezoelectric layer; a substrate opposed to the first principal surface of the piezoelectric layer with a space therebetween in the first direction, including a second functional electrode, and having a thickness in the first direction; and a shield between the piezoelectric layer and the substrate; wherein the shield is located at a position at least partially overlapping the first functional electrode in plan view in the first direction; and a distance from a center of the shield to the piezoelectric layer is smaller than a distance from the center of the shield to the substrate.
  2. 2 . The piezoelectric device according to claim 1 , wherein the support includes a void portion at a position at least partially overlapping the first functional electrode in plan view in the first direction.
  3. 3 . The piezoelectric device according to claim 1 , wherein the shield is located at a position at least partially overlapping the second functional electrode in plan view in the first direction.
  4. 4 . The piezoelectric device according to claim 1 , further comprising: a seal between the piezoelectric layer and the substrate; wherein the first functional electrode is located in a region surrounded by the seal in plan view in the first direction; a void surrounded by the piezoelectric layer, the substrate, and the seal is airtight; and a pressure inside the void is higher than an atmospheric pressure.
  5. 5 . The piezoelectric device according to claim 1 , wherein a distance from the shield to the first principal surface of the piezoelectric layer at the center of the shield is different from a distance from the shield to the first principal surface of the piezoelectric layer at a position other than the center of the shield; and the distance from the center of the shield to the piezoelectric layer is smaller than the distance from the position other than the center of the shield to the piezoelectric layer.
  6. 6 . The piezoelectric device according to claim 1 , further comprising: a covering layer on a surface of the shield; wherein the covering layer has a lower electric conductivity than an electric conductivity of the shield and a higher thermal conductivity than a thermal conductivity of the shield.
  7. 7 . The piezoelectric device according to claim 1 , further comprising: a covering layer on a surface of the shield; wherein the covering layer has a lower electric conductivity than an electric conductivity of the shield and a higher emissivity than an emissivity of the shield.
  8. 8 . The piezoelectric device according to claim 1 , wherein the piezoelectric layer includes lithium niobate, lithium tantalate, or crystal.
  9. 9 . The piezoelectric device according to claim 1 , wherein the first functional electrode includes an upper electrode on the first principal surface and a lower surface on the second principal surface.
  10. 10 . The piezoelectric device according to claim 9 , wherein the upper electrode includes an upper circular main electrode portion and an upper extending portion extending from the upper circular main electrode; and the lower electrode includes a lower circular main electrode portion and a lower extending portion extending from the lower circular main electrode.
  11. 11 . The piezoelectric device according to claim 9 , wherein each of the upper and lower electrodes includes aluminum, platinum, copper, tungsten, or molybdenum, or an alloy including at least one of aluminum, platinum, copper, tungsten, or molybdenum.
  12. 12 . The piezoelectric device according to claim 9 , wherein each of the upper and lower electrodes includes an adhesive layer including titanium or a nickel-chromium alloy.
  13. 13 . The piezoelectric device according to claim 1 , wherein the support includes a support substrate and an intermediate layer between the support substrate and the piezoelectric layer.
  14. 14 . The piezoelectric device according to claim 13 , wherein the support substrate includes silicon or crystal.
  15. 15 . The piezoelectric device according to claim 13 , wherein the intermediate layer includes silicon oxide.
  16. 16 . The piezoelectric device according to claim 1 , further comprising: a second piezoelectric layer on the substrate; wherein the second functional electrode is provided on a surface of the second piezoelectric layer facing the piezoelectric layer; wherein the shield is located between the piezoelectric layer and the second piezoelectric layer.
  17. 17 . The piezoelectric device according to claim 1 , wherein the shield includes aluminum, copper, gold, or silver.
  18. 18 . The piezoelectric device according to claim 1 , wherein the shield is electrically connected to ground.
  19. 19 . The piezoelectric device according to claim 1 , wherein the shield has an arch shape.
  20. 20 . The piezoelectric device according to claim 4 , wherein the seal includes a first portion, a second portion, and a bonding portion between the first and second portions; the first and second portions include aluminum; and the bonding portion includes gold.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to Japanese Patent Application No. 2023-123666 filed on Jul. 28, 2023 and is a Continuation Application of PCT Application No. PCT/JP2024/019083 filed on May 23, 2024. The entire contents of each application are hereby incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to piezoelectric devices. 2. Description of the Related Art Japanese Unexamined Patent Application Publication No. 2005-252175 and Japanese Unexamined Patent Application Publication No. 2018-014717 disclose piezoelectric devices each of which includes two substrates that are opposed to each other with a distance therebetween, and is provided with a shield located between the two substrates so as to cover a functional electrode provided to one of the substrates. The piezoelectric devices according to Japanese Unexamined Patent Application Publication No. 2005-252175 and Japanese Unexamined Patent Application Publication No. 2018-014717 are not capable of sufficiently dissipating operating heat from the functional electrode. SUMMARY OF THE INVENTION Example embodiments of the present invention provide piezoelectric devices each having a high heat dissipation property of a functional electrode. A piezoelectric device according to an example embodiment of the present invention includes a piezoelectric layer having a thickness in a first direction and including a first principal surface and a second principal surface on an opposite side from the first principal surface, a support on a second principal surface side of the piezoelectric layer, a first functional electrode on at least one of the first principal surface and the second principal surface of the piezoelectric layer, a substrate opposed to the first principal surface of the piezoelectric layer with a space in the first direction therebetween, including a second functional electrode, and having a thickness in the first direction, and a shield between the piezoelectric layer and the substrate. The shield is located at a position at least partially overlapping the first functional electrode in plan view in the first direction, and a distance from a center of the shield to the piezoelectric layer is smaller than a distance from the center of the shield to the substrate. According to example embodiments of the present invention, piezoelectric devices each having a high heat dissipation property of a functional electrode are provided. The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing an example of a piezoelectric device according to a first example embodiment of the present invention. FIG. 2 is a schematic plan view of the piezoelectric device according to the first example embodiment, which is viewed from a cross-section taken along line A-A in FIG. 1. FIG. 3 is a schematic plan view of the piezoelectric device according to the first example embodiment, which is viewed from the cross-section taken along line A-A in FIG. 1. FIG. 4 is a plan view showing a modification of the piezoelectric device according to the first example embodiment of the present invention. FIG. 5 is a diagram for explaining an example of a method of manufacturing the piezoelectric device according to the first example embodiment of the present invention. FIG. 6 is a diagram for explaining an example of a method of manufacturing the piezoelectric device according to the first example embodiment of the present invention. FIG. 7 is a diagram for explaining an example of a method of manufacturing the piezoelectric device according to the first example embodiment of the present invention. FIG. 8 is a schematic sectional view showing an example of a piezoelectric device according to a second example embodiment of the present invention. FIG. 9 is a schematic sectional view showing an example of a piezoelectric device according to a third example embodiment of the present invention. DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS Example embodiments of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to the example embodiments. The respective example embodiments described in this disclosure are merely exemplary, and in modifications as well as in second and subsequent example embodiments that enable partial replacement or combination of configurations between different example embodiments, descriptions concerning matters common to the first example embodiment will be omitted and only different points therefrom will be explained. In particular, the same operations and advantageous effects attributed to the same or substantially the same config