CN-114070240-B - Elastic wave device and method for manufacturing same

Abstract

An elastic wave device includes a piezoelectric substrate, an IDT, and a pattern wiring, wherein the IDT is a pair of comb electrodes formed on the piezoelectric substrate, each of the comb electrodes is composed of a first metal and a second metal, each of the comb electrodes has a plurality of electrode fingers interposed therebetween, the pattern wiring is formed on the piezoelectric substrate, each of the comb electrodes is composed of a first metal and a second metal, and the pattern wiring is electrically connected to the IDT, and a content of the second metal in a total amount of the first metal and the second metal of the IDT is higher than a content of the second metal in a total amount of the first metal and the second metal of the pattern wiring. Thus, an elastic wave device having excellent power resistance and bondability is provided.

Inventors

• MOTOYAMA KEIICHIRO
• Takata atsuya

Assignees

• 三安日本科技株式会社

Dates

Publication Date

20260508

Application Date

20210709

Priority Date

20200803

Claims (9)

1. 1. An elastic wave device, comprising: A piezoelectric substrate; an IDT formed on the piezoelectric substrate and composed of a first metal and a second metal and having a plurality of electrode fingers interposed therebetween, and A pattern wiring formed on the piezoelectric substrate, made of a first metal and a second metal, and electrically connected to the IDT, the pattern wiring being characterized in that: The content of the second metal in the total amount of the first metal and the second metal of the IDT is higher than the content of the second metal in the total amount of the first metal and the second metal of the pattern wiring, the content of the second metal in the total amount of the first metal and the second metal of the IDT is 1.5%, and the content of the second metal in the total amount of the first metal and the second metal of the pattern wiring is 0.5%.
2. 2. The elastic wave device according to claim 1, wherein the first metal has a higher linear expansion coefficient than the second metal.
3. 3. The elastic wave device according to claim 1, wherein the first metal is aluminum.
4. 4. The elastic wave device according to claim 1, wherein the second metal is copper.
5. 5. The elastic wave device according to claim 1, wherein the piezoelectric substrate is a lithium tantalate, lithium niobate, or a crystal piezoelectric single crystal, or a piezoelectric ceramic.
6. 6. The elastic wave device according to claim 1, wherein the piezoelectric substrate is bonded with a substrate made of sapphire, silicon, polycrystalline alumina, polycrystalline spinel, crystal, or glass on a principal surface opposite to a surface on which the IDT and the pattern wiring are formed.
7. 7. The elastic wave device according to claim 1, wherein the elastic wave device comprises: Bumps bonded on pads in the pattern wiring; a wiring substrate electrically connected to the pattern wiring via the bump, and And a sealing portion that seals a space between the piezoelectric substrate and the wiring substrate to form a hollow sealed space.
8. 8. A method for manufacturing an elastic wave device is characterized by comprising the steps of: forming a pattern wiring composed of a first metal and a second metal on a piezoelectric substrate using a photoresist; Forming a metal film composed of a first metal and a second metal while the photoresist layer remains on the pattern wiring, and Etching the metal film to form an IDT having a pair of comb-shaped electrodes with a plurality of electrode fingers interposed therebetween, wherein the content of the second metal in the total amount of the first metal and the second metal of the IDT is higher than the content of the second metal in the total amount of the first metal and the second metal of the pattern wiring, the content of the second metal in the total amount of the first metal and the second metal of the IDT is 1.5%, and the content of the second metal in the total amount of the first metal and the second metal of the pattern wiring is 0.5%.
9. 9. The method of manufacturing an elastic wave device according to claim 8, wherein the first metal is aluminum and the second metal is copper.

Description

Elastic wave device and method for manufacturing same Technical Field The present invention relates to a surface acoustic wave (SAW: surface Acoustic Wave) device and a method of manufacturing the same. Background Conventionally, a filter (elastic wave device) using a surface elastic wave is widely used for a transmission/reception circuit of a mobile phone or the like. With such a basic configuration, as described in many manuals, IDTs (INTERDIGITAL TRANSDUCER, interdigital transducers) for exciting an elastic surface are formed on a piezoelectric substrate made of lithium tantalate, lithium niobate, or the like, as resonators. Sometimes, a plurality of resonators are formed appropriately, and a DMS design or a ladder design is employed to construct a desired bandpass filter. In addition, some elastic wave devices require high power resistance. As described in wo2009/150786 of patent document 1, in order to provide an elastic wave device which is miniaturized, has improved power resistance, and is less likely to generate a protrusion such as a hillock, IDT is formed of an aluminum-copper alloy film formed by adding a predetermined amount of copper. The main problems to be solved by the present invention will be described below. When pure aluminum is used as the metal material of the pattern wiring or IDT of the acoustic wave device, the pattern wiring or IDT may form a protrusion, and there is a problem that the electric power resistance is weak. The protrusion is a load due to film stress caused by temperature change in the process, or occurs at the pattern wiring or IDT when a high voltage is applied. While the protrusion reduces the power resistance of the IDT. In this regard, as described in patent document 1, a technique of adding copper to suppress the occurrence of a protrusion to improve the power resistance has been disclosed. However, copper is added to ensure sufficient power resistance, which increases the copper content, and the bondability between the gold bump and the pad of the pattern wiring may be reduced, which may cause poor connection. Disclosure of Invention The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an elastic wave device with high reliability, which can suppress the occurrence of a protrusion, ensure sufficient power resistance, improve the bondability, and reduce the occurrence of a connection failure. In order to achieve the above object, an elastic wave device of the present invention includes: A piezoelectric substrate; an IDT formed on the piezoelectric substrate and composed of a first metal and a second metal and having a plurality of electrode fingers interposed therebetween, and And a pattern wiring formed on the piezoelectric substrate and made of a first metal and a second metal, and electrically connected to the IDT, wherein a content of the second metal in a total amount of the first metal and the second metal of the IDT is higher than a content of the second metal in a total amount of the first metal and the second metal of the pattern wiring. In one embodiment of the elastic wave device of the present invention, the first metal has a higher linear expansion coefficient than the second metal. In one embodiment of the elastic wave device of the present invention, the content of the second metal in the total amount of the first metal and the second metal in the IDT is 3 times the content of the second metal in the total amount of the first metal and the second metal in the pattern wiring. In one aspect of the elastic wave device of the present invention, the first metal is aluminum. In one aspect of the elastic wave device of the present invention, the second metal is copper. In one embodiment of the elastic wave device of the present invention, the piezoelectric substrate is a lithium tantalate, lithium niobate, or a crystal piezoelectric single crystal, or is a piezoelectric ceramic. In one embodiment of the acoustic wave device of the present invention, the piezoelectric substrate is bonded with a substrate made of sapphire, silicon, polycrystalline alumina, polycrystalline spinel, crystal, or glass on a principal surface opposite to a surface on which the IDT and the pattern wiring are formed. An elastic wave device according to one aspect of the present invention includes a bump bonded to a pad in the pattern wiring, a wiring board electrically connected to the pattern wiring via the bump, and a sealing portion sealing a space between the piezoelectric substrate and the wiring board to form a hollow sealed space. In addition, another aspect of the present invention provides a method for manufacturing an elastic wave device, comprising: forming a pattern wiring composed of a first metal and a second metal on a piezoelectric substrate using a photoresist; and etching the metal film to form an IDT having a pair of comb electrodes with a plurality of electrode fingers interposed therebe