METHOD FOR MANUFACTURING SURFACE ACOUSTIC WAVE ELEMENT AND SURFACE ACOUSTIC WAVE ELEMENT

Abstract

A method for manufacturing a surface acoustic wave element having an interdigital transducer (IDT) electrode formed on a semiconductor substrate includes a) forming an insulation layer on a surface of an active side of the semiconductor substrate, b) forming a base layer on a whole surface of the insulation layer, c) planarizing a surface of the base layer, d) forming a piezoelectric member on a planarized surface of the base layer, e) forming the IDT electrode on a surface of the piezoelectric member, and f) forming a bank being higher than a height from the surface of the base layer to the surface of the IDT electrode on a peripheral of the surface of the base layer so as to surround the piezoelectric member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.

FIGS. 1A and 1B show a schematic structure of a surface acoustic wave element according to the invention. FIG. 1A is a plan view thereof. FIG. 1B is a cross-sectional view taken along the line A-A in FIG. 1A.

FIGS. 2A through 2F are schematic sectional-views showing manufacturing steps for the surface acoustic wave element according to a first embodiment of the invention.

FIGS. 3A through 3E are schematic sectional-views showing the manufacturing steps for the surface acoustic wave element according to the first embodiment of the invention.

FIG. 4 is a schematic sectional-view showing a part of manufacturing steps for a surface acoustic wave element according to a second embodiment of the invention.

FIG. 5 is a schematic sectional-view showing a part of a modification of the second embodiment of the invention.

FIGS. 6A through 6H are schematic sectional-views showing major manufacturing steps for a surface acoustic wave element according to a third embodiment of the invention.

FIGS. 7A through 7H are schematic sectional-views showing major manufacturing steps for a surface acoustic wave element according to a fourth embodiment of the invention.

Claims

1. A method for manufacturing a surface acoustic wave element having an interdigital transducer (IDT) electrode formed on a semiconductor substrate, comprising: a) forming an insulation layer on a surface of an active side of the semiconductor substrate;b) forming a base layer on a whole surface of the insulation layer;c) planarizing a surface of the base layer;d) forming a piezoelectric member on a planarized surface of the base layer;e) forming the IDT electrode on a surface of the piezoelectric member; andf) forming a bank being higher than a height from the surface of the base layer to the surface of the IDT electrode on a peripheral of the surface of the base layer so as to surround the piezoelectric member.

2. The method for manufacturing a surface acoustic wave element according to claim 1, wherein step b) includes forming a single insulation layer.

3. The method for manufacturing a surface acoustic wave element according to claim 1, wherein step b) includes forming the base layer by laminating an Al layer and the insulation layer, and planarizing at least a surface of the Al layer.

4. The method for manufacturing a surface acoustic wave element according to claim 1, wherein step f) includes forming a bank layer to be as high as the bank on the surface of the base layer and forming a recess by removing the bank layer by etching to reach the surface of the base layer in a region to form the piezoelectric member, and the piezoelectric member in step d) is formed on a bottom of the recess.

5. The method for manufacturing a surface acoustic wave element according to claim 1, wherein step e) is followed by step f), and step f) includes: forming the bank in a predetermined shape by discharging a liquid member having a precursor compound for SiO2 in a region to form the bank on the peripheral of the surface of the base layer using a droplet discharge method; andsolidifying the liquid member by heat treatment.

6. The method for manufacturing a surface acoustic wave element according to claim 1, wherein step f) includes: forming the bank in a predetermined shape by discharging a liquid member having a precursor compound for SiO2 in a region to form the bank on the peripheral of the surface of the base layer using a droplet discharge method; andsolidifying the liquid member by heat treatment,

7. The method for manufacturing a surface acoustic wave element according to claim 5, wherein the bank is made of SiO2 and formed by solidifying a precursor compound for SiO2 being a liquid member including an organic metal compound Si (OR) 4(R=CH3, C2H5, C3H7, C4H9) with heat treatment.

8. The method for manufacturing a surface acoustic wave element according to claim 5, wherein a temperature for the heat treatment is in a range from 350 to 400 degrees centigrade.

9. A surface acoustic wave element having an interdigital transducer (IDT) electrode formed on a semiconductor substrate, comprising: an insulation layer formed on a surface of an active side of the semiconductor substrate;a base layer formed on a whole surface of the insulation layer and planarized;a piezoelectric member formed on a planarized surface of the base layer;the IDT electrode formed on a surface of the piezoelectric member; anda bank formed being higher than a height from the surface of the base layer to the surface of the IDT electrode on a peripheral of the surface of the base layer so as to surround the piezoelectric member.

10. The surface acoustic wave element according to claim 9, wherein a sealing member to seal a recess formed by the bank is further provided on a top surface of the bank and packaged.