Surface acoustic wave device and associated production method

Patent metadata

Field	Value
Publication number	US-2018309426-A1
Application number	US-201615769684-A
Country	US
Kind code	A1
Filing date	Oct 17, 2016
Priority date	Oct 20, 2015
Publication date	Oct 25, 2018
Grant date	—

Abstract

A production method for a surface acoustic wave device comprises the following steps: a step of providing a piezoelectric substrate comprising a transducer arranged on the main front face; a step of depositing a dielectric encapsulation layer on the main front face of the piezoelectric substrate and on the transducer; and a step of assembling the dielectric encapsulation layer with the main front face of a support substrate having a coefficient of thermal expansion less than that of the piezoelectric substrate. In additional embodiments, a surface acoustic wave device comprises a layer of piezoelectric material equipped with a transducer on a main front face, arranged on a substrate support of which the coefficient of thermal expansion is less than that of the piezoelectric material. The transducer is arranged in a dielectric encapsulation layer, between the layer of piezoelectric material and the support substrate.

First claim

1 . A method of producing a surface acoustic wave device, comprising the following steps:
a step of providing a piezoelectric substrate comprising a transducer on a main front face of the piezoelectric substrate; a step of depositing a dielectric encapsulation layer on the main front face of the piezoelectric substrate and on the transducer; a step of assembling the dielectric encapsulation layer with a main front face of a support substrate having a coefficient of thermal expansion less than that of the piezoelectric substrate.

2 . The method of claim 1 , wherein the transducer comprises a metallic interdigital electrodes structure.

3 . The method of claim 1 , wherein the piezoelectric substrate comprises vias in electrical contact with the transducer, extending across the thickness of the piezoelectric substrate from the main front face to a given depth.

4 . The method of claim 1 , wherein the piezoelectric substrate is a massive substrate comprises at least one material selected from the group consisting of LiNbO 3 , LiTaO 3 , BaTiO 3 , quartz, lead zirconate titanate (PZT), ZnO, and AlN.

5 . The method of claim 1 , wherein the dielectric encapsulation layer comprises at least one material selected from the group consisting of: SiO 2 , SiN, SiON, SiOC, SiC, DLC, alumina, hafnium silicate, zirconium silicate, hafnium dioxide, and zirconium dioxide.

6 . The method of claim 1 , wherein a planarization step follows the step of depositing the dielectric encapsulation layer.

7 . The method of claim 1 , wherein the support substrate has a resistivity of more than 100 ohms-cm.

8 . The method of claim 1 , wherein the support substrate comprises a material selected from the group consisting of: silicon, sapphire, glass, ceramics, and plastics.

9 . The method of claim 1 , wherein the support substrate comprises a complementary dielectric layer on the main front face.

10 . The method of claim 1 , wherein the support substrate is thermally expanded.

11 . The method of claim 10 , wherein the support substrate is an anti-reflective layer.

12 . The method of claim 1 , wherein the assembly step comprises direct bonding by molecular adhesion.

13 . The method of claim 1 , wherein the assembly step is followed by a step for thinning a main rear face of the piezoelectric substrate.

14 . The method of claim 13 , wherein the step for thinning comprises grinding, mechanical-chemical polishing or chemical attack.

15 . The method of claim 14 , wherein the step for thinning culminates in a residual piezoelectric substrate layer of between 2 microns to 200 microns.

16 . The method of claim 15 , wherein the piezoelectric substrate comprises vias in electrical contact with the transducer, extending across the thickness of the piezoelectric substrate from the main front face to a given depth and the residual piezoelectric substrate layer of the piezoelectric substrate has a thickness of less than or equal to the determined depth of the vias.

17 . The method of claim 16 , wherein the thinning step is followed by a step of depositing an anti-reflective layer on the residual piezoelectric substrate layer of the piezoelectric substrate.

18 . The method of claim 17 , wherein the thinning step is followed by a support substrate thickening step resulting in a support layer thickness of 10 microns to 250 microns.

19 . The method of claim 18 , wherein the thinning or thickening step is followed by a step of forming vias at a main rear face of the support substrate or the support layer, the vias extending to the transducer and in electrical contact with the transducer.

20 . The method of claim 16 , wherein the method further comprises a step for the formation of contacts at the vias.

21 . A surface acoustic wave device comprising a layer of piezoelectric material having a transducer on a main front face, arranged on a substrate support of which the coefficient of thermal expansion is less than that of the piezoelectric material, wherein the transducer is arranged in a dielectric encapsulation layer, between the layer of piezoelectric material and the support substrate.

22 . The surface acoustic wave device of claim 21 , wherein the layer of piezoelectric material comprises conductive vias in electrical contact with the transducer, and extending across the layer of piezoelectric material from the main front face to a main rear face.

23 . The surface acoustic wave device of claim 21 , wherein the support substrate comprises conductive vias in electrical contact with the transducer, extending across the support substrate from a main front face to a main rear face.

Assignees

• Soitec Silicon On Insulator

Inventors

• Guenard Pascal
• Radu Ionut

Classifications

• H03H9/02574

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

• H03H9/02834 Primary

  of temperature influence (cut angles H03H9/02543) · CPC title

• H03H9/145

  for networks using surface acoustic waves · CPC title

• H01L41/0475

  Electricity · mapped topic

• H03H9/02984

  Protection measures against damaging · CPC title