Composite Substrate, Elastic Wave Device, and Method for Producing Elastic Wave Device

Patent metadata

Field	Value
Publication number	US-2015328875-A1
Application number	US-201514811953-A
Country	US
Kind code	A1
Filing date	Jul 29, 2015
Priority date	Feb 19, 2013
Publication date	Nov 19, 2015
Grant date	—

Abstract

A composite substrate 10 is formed by bonding together a piezoelectric substrate 12 and a support substrate 14 that has a lower thermal expansion coefficient than the piezoelectric substrate. The support substrate 14 is formed by directly bonding together a first substrate 14 a and a second substrate 14 b at a strength that allows separation with a blade, the first and second substrates being formed of the same material, and a surface of the first substrate 14 a is bonded to the piezoelectric substrate 12 , the surface being opposite to another surface of the first substrate 14 a bonded to the second substrate 14 b.

First claim

What is claimed is:

1 . A composite substrate formed by bonding together a piezoelectric substrate and a support substrate that has a lower thermal expansion coefficient than the piezoelectric substrate,
wherein the support substrate is formed by directly bonding together a first substrate and a second substrate at a strength that allows separation with a blade, the first and second substrates being formed of the same material; and a surface of the first substrate is bonded to the piezoelectric substrate, the surface being opposite to another surface of the first substrate bonded to the second substrate.

2 . The composite substrate according to claim 1 ,
wherein the first and second substrates are both silicon substrates.

3 . The composite substrate according to claim 1 ,
wherein the strength that allows separation with a blade corresponds to a bonding energy per unit area of the first and second substrates in a range of 0.05 to 0.6 J/m 2 .

4 . The composite substrate according to claim 1 ,
wherein the first and second substrates have a thickness of 100 to 600 μm.

5 . A method for producing an elastic wave device, comprising the steps of:
(a) preparing the composite substrate according to claim 1 ; (b) forming electrodes for elastic wave devices, on a surface of the piezoelectric substrate of the composite substrate; (c) removing the second substrate from the first substrate by separation with a blade; and (d) dicing the composite substrate to obtain elastic wave devices.

6 . The method for producing an elastic wave device according to claim 5 ,
wherein, in the step (a), the first substrate and the second substrate are directly bonded together at the strength that allows separation with the blade to form the support substrate, and the support substrate and the piezoelectric substrate are subsequently bonded together directly or with resin.

7 . An elastic wave device obtained by the method for producing an elastic wave device according to claim 5 .

8 . An elastic wave device obtained by the method for producing an elastic wave device according to claim 6 .

9 . The elastic wave device according to claim 7 ,
wherein the first substrate is a silicon substrate on a back surface of which iron and chromium elements are present.

10 . The elastic wave device according to claim 8 ,
wherein the first substrate is a silicon substrate on a back surface of which iron and chromium elements are present.

Assignees

• Ngk Insulators Ltd

Inventors

• Hattori Ryosuke
• Hori Yuji
• Tai Tomoyoshi

Classifications

• H10P54/00

  Cutting or separating of wafers, substrates or parts of devices · CPC title

• H10P72/74 Primary

  using temporarily an auxiliary support · CPC title

• B32B37/10

  characterised by the pressing technique, e.g. using action of vacuum or fluid pressure · CPC title

• H03H9/02574

  of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate · CPC title

• B32B2309/02

  Temperature · CPC title