Solid state electronic device

• US 4,942,327 A
• Filed: 05/26/1989
• Issued: 07/17/1990
• Est. Priority Date: 06/01/1988
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Watanabe, Hitoshi, Yamada, Jun, Yuhara, Akitsuna, Hosaka, Norio
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US07/357,464
• Time in Patent Office: 417 Days
• Field of Search: 310/313 R, 310/313 A, 310/313 B, 310/363, 310/364
• US Class Current: 310/313.00R
• CPC Class Codes: G10K 11/36 Devices for manipulating acoustic surface waves electro-acoustic amplifiers H03F13/00; networks comprising electro-acoustic elements H03H9/00
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H03H 9/02929 of ageing changes of characteristics, e.g. electro-acousto-migration
• CPC Class Codes: H03H 9/14538 Formation

Abstract

A solid state electronic device having a thin film of an Al (aluminum) alloy Li (lithium) on the surface of a substrate for a surface acoustic wave (SAW). Interdigital electrodes, electric wiring patterns and bonding pads are formed by the thin film of the Li-added Al alloy. This thin film suppresses migration which occurs when a high density current is supplied to the device or a large amplitude SAW is generated. The thin film, which provides a small loss and relatively low hardness, provides a desired power handling capability and high yield of wire bonding. The this film assures high endurance to failure of the device and sufficient life of the device.

Claims

1. A solid state electronic device comprising:

a substrate along which a surface acoustic wave propagates, and

a conductive thin film provided on the surface of said substrate, said conductive thin film constituting at least one of electrodes, electric wiring patterns and bonding pads, wherein at least a part of said conductive thin film is made of a first aluminum alloy added with lithium by 0.05-3 wt %.

2. A solid state electronic device according to claim 1, wherein first aluminum alloy has a grain size set to 0.05 μ

m or less.

3. A solid state electronic device according to claim 1, wherein said conductive thin film consists of a first thin film of said Al alloy and a second thin film of pure aluminum, which are laminated in a multi-layer structure.

4. A solid state electronic device according to claim 2, wherein said conductive thin film consists of a first thin film of said Al alloy and a second thin film of pure aluminum, which are laminated in a multi-layer structure.

5. A solid state electronic device according to claim 1, wherein said conductive thin film consists of a first thin film of said Al alloy and a third thin film of a second Al alloy, which are laminated in a multi-layer structure.

6. A solid state electronic device according to claim 2, wherein said conductive thin film consists of a first thin film of said Al alloy and a third thin film of a second Al alloy, which are laminated in a multi-layer structure.

7. A solid state electronic device according to claim 1, wherein said substrate is made of ST-cut quartz, and said electrodes include a set of interdigital electrodes and a pair of grating reflectors provided on both sides of said interdigital electrodes, each grating reflector consisting of a plurality of metal strips.

8. A solid state electronic device according to claim 1, wherein said substrate is made of LiTaO₃ cut the crystal 36°

rotated around the Y-axis thereof, and said electrodes include a set of electrodes consisting of a plurality of interdigital electrodes with different resonant frequencies connected in series and a shield electrode provided intermediately between said set of electrodes.