Piezoelectric device and method for manufacturing piezoelectric device

Patent metadata

Field	Value
Publication number	US-2016284979-A1
Application number	US-201615074005-A
Country	US
Kind code	A1
Filing date	Mar 18, 2016
Priority date	Mar 27, 2015
Publication date	Sep 29, 2016
Grant date	—

Abstract

A piezoelectric device includes a substrate, a lower electrode disposed above the substrate, a lower bonding layer disposed on the lower electrode, a piezoelectric layer containing a piezoelectric material disposed on an upper surface of the lower bonding layer, and an upper electrode disposed above the piezoelectric layer. The lower bonding layer includes an electrode material portion containing an electrode material of the lower electrode and a piezoelectric material portion containing a piezoelectric material. The electrode material portion and the piezoelectric material portion interdigitate with each other in the lower bonding layer.

First claim

What is claimed is:

1 . A piezoelectric device comprising:
a substrate; a lower electrode disposed above the substrate, the lower electrode being made of a first electrode material; a lower bonding layer disposed on an upper surface of the lower electrode; a piezoelectric layer disposed on an upper surface of the lower bonding layer, the piezoelectric layer containing a piezoelectric material; and an upper electrode disposed above an upper surface of the piezoelectric layer, wherein the lower bonding layer includes a first electrode material portion containing the first electrode material and a first piezoelectric material portion containing the piezoelectric material, wherein the first electrode material portion and the first piezoelectric material portion interdigitate with each other in the lower bonding layer.

2 . The piezoelectric device according to claim 1 ,
wherein the first electrode material portion includes a plurality of first protrusions bonded to the lower electrode and protruding from the lower electrode toward the piezoelectric layer, wherein the first piezoelectric material portion is bonded to the piezoelectric layer, wherein the plurality of first protrusions are covered with the first piezoelectric material portion in the lower bonding layer.

3 . The piezoelectric device according to claim 2 ,
wherein each first protrusion of the plurality of first protrusions has a root bonded to the lower electrode and a tip end opposite to the root, wherein the each first protrusion has a first portion having a first diameter and a second portion located having a second diameter larger than the first diameter, the second portion being closer to the root than the first portion, and wherein the first electrode material portion and the first piezoelectric material portion are bonded to each other via the plurality of first protrusions.

4 . The piezoelectric device according to claim 3 , wherein a ratio of a weight of the first electrode material portion to a weight the first piezoelectric material portion in the lower bonding layer ranges from 12/88 to 55/45.

5 . The piezoelectric device according to claim 2 , further comprising
an upper bonding layer disposed between the piezoelectric layer and the upper electrode, wherein the upper electrode is made of a second electrode material, wherein the upper bonding layer includes a second piezoelectric material portion containing the piezoelectric material and a second electrode material portion containing the second electrode material, and wherein the second electrode material portion and the second piezoelectric material portion interdigitate with each other in the upper bonding layer.

6 . The piezoelectric device according to claim 5 ,
wherein the second electrode material portion includes a plurality of second protrusions bonded to the upper electrode and protruding from the upper electrode toward the piezoelectric layer, wherein the second piezoelectric material portion is bonded to the piezoelectric layer, and wherein the plurality of second protrusions are covered with the second piezoelectric material portion in the upper bonding layer.

7 . The piezoelectric device according to claim 1 , wherein the substrate is made of stainless steel.

8 . The piezoelectric device according to claim 1 ,
wherein the first piezoelectric material portion includes a plurality of protrusions bonded to the piezoelectric layer and protruding from the piezoelectric layer toward the lower electrode, wherein the first electrode material portion is bonded to the lower electrode, and wherein the plurality of protrusions are covered with the first electrode material portion in the lower bonding layer.

9 . The piezoelectric device according to claim 1 , wherein the piezoelectric layer has a lower surface located on the upper surface of the lower bonding layer and a side surface connected to the upper surface and the lower surface of the piezoelectric layer, and the side surface of the piezoelectric layer includes a peripheral portion connected to the lower surface of the piezoelectric layer, the piezoelectric device further comprising a cover for covering a peripheral portion of the side surface of the piezoelectric layer.

10 . The piezoelectric device according to claim 9 , wherein the cover is made of material identical to material of the lower bonding layer.

11 . The piezoelectric device according to claim 9 , wherein the cover is made of the first electrode material.

12 . A method for manufacturing a piezoelectric device, comprising:
providing a lower electrode material paste, a piezoelectric material paste, and an upper electrode material paste; providing a lower bonding material paste obtained by mixing the piezoelectric material paste and the lower electrode material paste; forming a lower electrode material layer by applying the lower electrode material paste so as to form a lower electrode above a substrate; forming a lower bonding material layer by applying the lower bonding material paste on an upper surface of the lower electrode material layer so as to form a lower bonding layer on the upper surface of the lower electrode material layer; forming a piezoelectric material layer on an upper surface of the lower bonding material layer by applying the piezoelectric material paste so as to form a piezoelectric layer on the upper surface of the lower bonding material layer; forming an upper electrode material layer by applying the upper electrode material paste so as to form an upper electrode above an upper surface of the piezoelectric material layer; and firing the lower electrode material layer, the lower bonding material layer, the piezoelectric material layer, and the upper electrode material layer.

13 . The method according to claim 12 , wherein a ratio of a weight of the lower electrode material paste to a weight of the piezoelectric material paste in the lower bonding material paste ranges from 12/88 to 55/45.

14 . The method according to claim 12 , wherein the piezoelectric material layer has a lower surface located on the upper surface of the lower bonding material layer and a side surface connected to the upper surface and the lower surface of the piezoelectric material layer, and the side surface of the piezoelectric material layer has a peripheral portion connected to the lower surface of the piezoelectric material layer, the method further comprising
applying the lower bonding material paste to cover the peripheral portion of the side surface of the piezoelectric material layer in order to form a cover layer.

15 . The method according to claim 12 , wherein the piezoelectric material layer has a lower surface located on the upper surface of the lower bonding material layer and a side surface connected to the upper surface and the lower surface of the piezoelectric material layer, and the side surface of the piezoelectric material layer includes a peripheral portion connected to the lower surface of the piezoelectric material layer, the manufacturing method further comprising
applying the lower electrode material paste to cover the peripheral portion of the side surface of the piezoelectric material layer in order to form a cover layer.

16 . The method according to claim 12 , further comprising:
providing an upper bonding material paste obtained by mixing the piezoelectric material paste and the upper electrode material paste; forming an upper bonding material layer by applying the upper bonding material paste on an upper surface of the piezoelectric material layer so as to form

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Fukui Takafumi
• Yamakoshi Kiyoshi
• Higashi Yoshiko

Classifications

• H01L41/297

  Electricity · mapped topic

• H01L41/0471

  Electricity · mapped topic

• H01L41/277 Primary

  Electricity · mapped topic

• H01L41/35

  Electricity · mapped topic

• H10N30/074

  by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing · CPC title