Acoustic wave device with adhesive layer and method of manufacturing the same

1. An acoustic wave device comprising:

a substrate;

an acoustic wave element provided on the substrate;

an electrode pad that is provided on the substrate, is electrically coupled to the acoustic wave element, and has an Au layer and an adhesive layer formed on the Au layer and having an opening;

a resin portion that is provided on the substrate so as to cover the acoustic wave element and the electrode pad, wherein the resin portion has a through-hole formed so as to expose a surface of the electrode pad;

a metal post that is provided in the through-hole and contacts with the Au layer through the opening of the adhesive layer; and

a Si compound layer that is provided between the adhesive layer and the resin portion and contacts with the adhesive layer and the resin portion,

wherein the adhesive layer is provided between the Au layer and the resin portion, and

wherein the adhesive layer is made of a material that provides for a degree of adhesion between the adhesive layer and the Si compound layer that is higher than the degree of adhesion between Au and the Si compound layer.

2. The acoustic wave device as claimed in claim 1 , wherein the adhesive layer is provided on top of and in contact with the Au layer.

3. The acoustic wave device as claimed in claim 1 , wherein the opening of the adhesive layer is defined with the through-hole of the resin portion.

4. The acoustic wave device as claimed in claim 1 , wherein the adhesive layer covers a side face of the Au layer.

5. The acoustic wave device as claimed in claim 1 , wherein a bottom layer of the electrode pad is made of the same material as an IDT of the acoustic wave element.

6. The acoustic wave device as claimed in claim 1 , wherein the adhesive layer is a Ti layer.

7. The acoustic wave device as claimed in claim 1 , wherein the Si compound layer is a silicon oxide layer or a silicon nitride layer.

8. The acoustic wave device as claimed in claim 1 , wherein the resin portion has a cavity on an excitation region of the acoustic wave element.

9. The acoustic wave device as claimed in claim 1 , wherein the resin portion has a first resin layer and a second resin layer,

the first resin layer having an opening for forming a cavity on an excitation region of the acoustic wave element,

the second resin layer covering the cavity.

10. The acoustic wave device as claimed in claim 1 , wherein the adhesive layer is made of Ti.

11. A method of manufacturing an acoustic wave device comprising:

forming an electrode pad that is provided on a substrate, is electrically coupled to an acoustic wave element on the substrate, and has an Au layer and an adhesive layer formed on the Au layer and having an opening;

forming a Si compound layer on to of and in contact with the adhesive layer;

forming a resin portion that is provided on the substrate so as to cover the acoustic wave element and the electrode pad, wherein the resin portion has a through-hole formed so as to expose a surface of the electrode pad; and

forming a metal post that is provided in the through-hole and contacts with the Au layer through the opening of the adhesive layer,

wherein the resin portion is formed so that the adhesive layer is formed between the Au layer and the resin portion, and

wherein the adhesive layer is made of a material that provides for a degree of adhesion between the adhesive layer and the Si compound layer that is higher than the degree of adhesion between Au and the Si compound layer.

12. The method as claimed in claim 11 , wherein the opening of the adhesive layer is formed with use of the through-hole.