Piezoelectric device and manufacturing method therefor

Patent metadata

Field	Value
Publication number	US-2017194937-A1
Application number	US-201715465631-A
Country	US
Kind code	A1
Filing date	Mar 22, 2017
Priority date	Oct 17, 2014
Publication date	Jul 6, 2017
Grant date	—

Abstract

A piezoelectric device includes a first piezoelectric substrate, a second piezoelectric substrate and an adhesive layer. First conductor patterns are provided on a front surface of the first piezoelectric substrate. A first piezoelectric element is defined by the first conductor patterns. Second conductor patterns are provided on a front surface of the second piezoelectric substrate. A second piezoelectric element is provided of these patterns. The adhesive layer adheres a rear surface of the first piezoelectric substrate and a rear surface of the second piezoelectric substrate to each other. The adhesive layer adheres the first and second substrates to each other such that a compressive stress is applied to the first and second piezoelectric substrates in a bonded state.

First claim

What is claimed is:

1 . A piezoelectric device comprising:
a first functional substrate that is made of a crystalline material having piezoelectric properties and that includes a first functional conductor pattern on a front surface thereof; a second functional substrate that includes a second functional conductor pattern on a front surface thereof; and an adhesive layer that affixes a rear surface of the first functional substrate and a rear surface of the second functional substrate to each other and that applies a compressive stress to the first functional substrate in an affixed state.

2 . A piezoelectric device comprising:
a first functional substrate that is made of a crystalline material having piezoelectric properties and that includes a first functional conductor pattern on a front surface thereof; a second functional substrate that includes a second functional conductor pattern on a front surface thereof; and an adhesive layer that affixes a rear surface of the first functional substrate and a rear surface of the second functional substrate to each other; wherein a crystal lattice spacing at the rear surface of the first functional substrate and the rear surface of the second functional substrate is smaller than a crystal lattice spacing at the front surface of the first functional substrate and the front surface of the second functional substrate.

3 . The piezoelectric device according to claim 2 , wherein the rear surface of the first functional substrate has a higher surface roughness than the front surface of the first functional substrate.

4 . The piezoelectric device according to claim 2 , wherein the second functional substrate is made of a material having piezoelectric properties, and the adhesive layer applies a compressive stress to the second functional substrate in a bonded state.

5 . The piezoelectric device according to claim 4 , wherein the rear surface of the second functional substrate has a higher surface roughness than the front surface of the second functional substrate.

6 . The piezoelectric device according to claim 1 , wherein the adhesive layer includes:
an adhesive resin; and a compressive stress applying agent that generates a compressive stress via a change in state.

7 . The piezoelectric device according to claim 1 , wherein the adhesive layer has a higher coefficient of linear expansion than the first functional substrate.

8 . The piezoelectric device according to claim 1 , wherein
an elastic wave propagation speed of the adhesive layer, which applies the compressive stress, is lower than an elastic wave propagation speed of the functional substrates; and an elastic modulus of the adhesive layer, which applies the compressive stress, is lower than an elastic modulus of the functional substrates.

9 . A piezoelectric device manufacturing method comprising:
forming a first functional conductor pattern on a front surface of a first functional substrate that is made of a material having piezoelectric properties; forming a second functional conductor pattern on a front surface of a second functional substrate; and applying a compressive stress to the first functional substrate by bonding a rear surface of the first functional substrate and a rear surface of the second functional substrate to each other.

10 . The piezoelectric device manufacturing method according to claim 9 , wherein
the second functional substrate is made of a material having piezoelectric properties; and a compressive stress is also applied to the second functional substrate in the applying a compressive stress.

11 . The piezoelectric device according to claim 1 , wherein the second functional substrate is a semiconductor substrate.

12 . The piezoelectric device according to claim 2 , wherein
electrically conductive bumps are provided on both the front surface of the first functional substrate and the front surface of the second functional substrate.

13 . The piezoelectric device manufacturing method according to claim 9 , further comprising a step of forming electrically conductive bumps on both the front surface of the first functional substrate and the front surface of the second functional substrate.

14 . An elastic wave device, comprising:
the piezoelectric device according to claim 2 ; a routing substrate; and electrically conductive bumps electrically connecting the piezoelectric device to the routing substrate.

15 . The elastic wave device according to claim 14 , wherein
lateral side surfaces of the piezoelectric device are encapsulated in insulating resin; and conductive vias are defined in the insulating resin to connect the routing substrate to additional electrically conductive bumps.

16 . An electronic appliance, comprising:
the elastic wave device according to claim 14 ; a mounted circuit element; a semiconductor element; and a base circuit board; wherein each of the elastic wave device, the mounted circuit element, and the semiconductor element board are positioned adjacent to one another on a surface of the base circuit board.

17 . The electronic appliance according to claim 16 , wherein the piezoelectric device is connected to the surface of the base circuit board through the electrically conductive bumps.

18 . The piezoelectric device according to claim 1 , wherein the first functional substrate is made of a lithium tantalate substrate or a lithium niobate substrate.

19 . The piezoelectric device according to claim 2 , wherein the first functional substrate is made of a lithium tantalate substrate or a lithium niobate substrate.

20 . The piezoelectric device manufacturing method according to claim 9 , wherein the first functional substrate is made of a lithium tantalate substrate or a lithium niobate substrate.

Assignees

• Murata Manufacturing Co

Inventors

• Iwamoto Takashi

Classifications

• H03H9/059

  consisting of mounting pads or bumps · CPC title

• H03H3/08

  for the manufacture of resonators or networks using surface acoustic waves · CPC title

• H03H9/145

  for networks using surface acoustic waves · CPC title

• H03H9/02866

  of bulk wave excitation and reflections · CPC title

• H03H9/1085

  the enclosure being defined by a non-uniform sealing mass covering the non-active sides of the SAW device · CPC title