# US 7,459,094 B2 · Method for making a surface acoustic wave device package

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- Number: US 7,459,094 B2
- Document ID: US7459094B2
- Status: Granted
- Kind: B2
- Application number: 11/675,751
- Filed: 2007-02-16
- Published: 2007-08-16
- Granted: 2008-12-02
- Earliest claimed: 2004-11-05
- Assignees: I-Shou University
- Inventors: Chi-Yen Shen
- Web page: https://patentgrep.com/patent/US7459094B2

## CPC

- H03H 3/08: for the manufacture of resonators or networks using surface acoustic waves
- C23F 1/02: Local etching
- H03H 9/0542: {consisting of a lateral arrangement (H03H9/0566 takes precedence)}
- H03H 9/059: {consisting of mounting pads or bumps}
- H03H 9/1085: {the enclosure being defined by a non-uniform sealing mass covering the non-active sides of the SAW device}
- H03H 9/1092: {the enclosure being defined by a cover cap mounted on an element forming part of the surface acoustic wave [SAW] device on the side of the IDT's}
- H10W 74/00: Encapsulations, e.g. protective coatings
- H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P)
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method for making a SAW device package includes the steps of: forming a pattern of a metal layer, that defines transmitting and receiving transducers of a SAW die, on a wafer; forming a pattern of a first photo sensitive layer, which defines a peripheral wall of a cap of the SAW die, on the metal layer and the wafer through lithography techniques; forming a pattern of a second photo sensitive layer, which defines a cover wall of the cap of the SAW die, on the first photo sensitive layer through lithography techniques; curing the first and second photo sensitive layers; dicing the wafer into SAW dies; and encapsulating the SAW dies with a molding compound.

## Claims

### Claim 1

A method for making a surface acoustic wave (SAW) device package that includes a SAW die having a piezoelectric substrate, and transmitting and receiving transducers and a cap formed on the substrate, the cap having a peripheral wall and a cover wall which cooperate with the substrate to define an embedded air cavity thereamong, said method comprising the steps of:
forming a pattern of lift-off layer on a wafer surface of a wafer through lithography techniques;
forming a metal layer on the wafer surface of the wafer and the lift-off layer through metallization techniques;
removing the lift-off layer and the metal layer on the lift-off layer by dissolving the lift-off layer in a solution so as to form a pattern of the metal layer, that defines the transmitting and receiving transducers of the SAW die, on the wafer surface of the wafer;
forming a pattern of a first photo sensitive layer, which defines the peripheral wall of the cap of the SAW die, on the metal layer and the wafer surface of the wafer through lithography techniques;
forming a pattern of a second photo sensitive layer, which defines the cover wall of the cap of the SAW die, on the first photo sensitive layer through lithography techniques;
curing the first and second photo sensitive layers;
dicing the wafer into SAW dies; and
encapsulating the SAW dies with a molding compound.

### Claim 2 (depends on 1)

The method of claim 1, wherein each of the first and second photo sensitive materials is selected from the group consisting of photoresists, epoxy resin, polyimide, benzocyclobutene, acrylic-based materials, and mixtures thereof.

### Claim 3

A method for making a SAW device package that includes a SAW die having a piezoelectric substrate, and transmitting and receiving transducers and a cap formed on the substrate, the cap having a peripheral wall and a cover wall which cooperate with the substrate to define an embedded air cavity thereamong, said method comprising the steps of:
forming a metal layer on a wafer surface of a wafer through metallization techniques;
forming a pattern of a photoresist layer on the metal layer through lithography techniques;
etching an exposed portion of the metal layer that is exposed from the photoresist layer so as to form a pattern of the metal layer, which defines the transmitting and receiving transducers of the SAW die, on the wafer surface of the wafer;
forming a pattern of a first photo sensitive layer, which defines the peripheral wall of the cap of the SAW die, on the metal layer and the wafer surface of the wafer through lithography techniques;
forming a pattern of a second photo sensitive layer, which defines the cover wall of the cap of the SAW die, on the first photo sensitive layer through lithography techniques;
curing the first and second photo sensitive layers;
dicing the wafer into SAW dies; and
encapsulating the SAW dies with a molding compound.

### Claim 4 (depends on 3)

The method of claim 3, wherein each of the first and second photo sensitive materials is selected from the group consisting of photoresists, epoxy resin, polyimide, benzocyclobutene, acrylic-based materials, and mixtures thereof.