Composite substrate, piezoelectric device, and method for manufacturing composite substrate

Patent metadata

Field	Value
Publication number	US-9680083-B2
Application number	US-201414565902-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Jul 12, 2012
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A composite substrate 10 includes a piezoelectric substrate 12 and a support layer 14 bonded to the piezoelectric substrate 12 . The support layer 14 is made of a material having no crystalline anisotropy in a bonded surface thereof and has a smaller thickness than the piezoelectric substrate 12 . The piezoelectric substrate 12 and the support layer 14 are bonded together with an adhesive layer 16 therebetween. The composite substrate 10 has a total thickness of 180 μm or less. The base thickness ratio Tr=t2/(t1+t2) is 0.1 to 0.4, where t1 is the thickness of the piezoelectric substrate 12 , and t2 is the thickness of the support layer 14 . The thickness t1 is 100 μm or less. The thickness t2 is 50 μm or less.

First claim

What is claimed is:

1. A composite substrate comprising:
a piezoelectric substrate including LiTaO 3 and having a thickness of 100 μm or less; and
a support layer bonded to the piezoelectric substrate, the support layer comprising a material having no crystalline anisotropy in a bonded surface thereof and having a thermal expansion coefficient smaller than that of the piezoelectric substrate,
wherein the support layer comprises borosilicate glass, a ceramics comprising ZnO, or a ceramics comprising alumina, and
the base thickness ratio Tr=t2/(t1+t2) is 0.1 to 0.3, where t1 is the thickness of the piezoelectric substrate, and t2 is the thickness of the support layer.

2. The composite substrate according to claim 1 , wherein the composite substrate has a total thickness of 100 μm or less.

3. A piezoelectric device comprising:
the composite substrate according to claim 1 ; and
electrodes formed on the piezoelectric substrate.

4. The composite substrate according to claim 1 , wherein the support layer has a thickness of 10 μm to 20 μm.

5. The composite substrate according to claim 2 , wherein the support layer has a thickness of 10 μm to 20 μm.

6. The composite substrate according to a claim 1 , wherein the piezoelectric substrate has a thickness of 80 μm or less.

7. The composite substrate according to a claim 2 , wherein the piezoelectric substrate has a thickness of 80 μm or less.

8. The composite substrate according to a claim 4 , wherein the piezoelectric substrate has a thickness of 80 μm or less.

9. The composite substrate according to a claim 5 , wherein the piezoelectric substrate has a thickness of 80 μm or less.

10. The composite substrate according to claim 1 , wherein the piezoelectric substrate has a thickness of 50 μm to 70 μm.

11. The composite substrate according to claim 2 , wherein the piezoelectric substrate has a thickness of 50 μm to 70 μm.

12. The composite substrate according to claim 4 , wherein the piezoelectric substrate has a thickness of 50 μm to 70 μm.

13. The composite substrate according to claim 5 , wherein the piezoelectric substrate has a thickness of 50 μm to 70 μm.

14. A piezoelectric device comprising:
the composite substrate according to claim 2 ; and
electrodes formed on the piezoelectric substrate.

15. A method for manufacturing a composite substrate, comprising the steps of:
(1) forming a support layer on a piezoelectric substrate including LiTaO 3 , the support layer comprising a material having no crystalline anisotropy in a surface thereof bonded to the piezoelectric substrate and having a thermal expansion coefficient smaller than that of the piezoelectric substrate; and
(2) polishing a surface of the piezoelectric substrate so that the piezoelectric substrate has a thickness of 100 μm or less,
wherein the support layer comprises borosilicate glass, a ceramics comprising ZnO, or a ceramics comprising alumina, and
the support layer is formed in the step (1) so that the base thickness ratio Tr=t2/(t1+t2) is 0.1 to 0.3, where t1 is the thickness of the piezoelectric substrate after being polished in the step (2) and t2 is the thickness of the support layer, or a surface of the support layer is polished during, before, or after the step (2) so that the base thickness ratio Tr=is 0.1 to 0.

Assignees

• Ngk Insulators Ltd

Inventors

• Hori Yuji
• Tai Tomoyoshi
• Hamajima Akira
• Nakahara Toshinao

Classifications

• Y10T428/2495

  Thickness [relative or absolute] · CPC title

• H03H3/08

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

• H03H9/02574 Primary

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

• H01L41/22

  Electricity · mapped topic

• H01L41/0805 Primary

  Electricity · mapped topic