Abstract: A method for manufacturing a boundary acoustic wave device prevents formation of discontinuous portions in a dielectric film without a significant decrease in the thickness of an IDT when the dielectric film is formed by deposition and without deterioration of electrical characteristics. The method includes the steps of forming an IDT on a piezoelectric substrate, forming a lower dielectric film so as to cover the IDT, conducting a planarizing step so as to smooth the rough surface of the lower dielectric film, and forming an upper dielectric film so as to cover the lower dielectric film of which the rough surface is smoothed.

Abstract: An acoustic wave device includes a piezoelectric substrate and an IDT electrode disposed thereon. The IDT electrode includes a metal laminate. The metal laminate includes a first metal layer made of Al or an Al-based alloy, a second metal layer made of a metal or alloy different from that used in the first metal layer, a Cu layer, and a Ti layer. The Cu layer and the Ti layer are disposed between the first and second metal layers. The Cu layer is located on the first metal layer side.

Abstract: A method for manufacturing a boundary acoustic wave device prevents formation of discontinuous portions in a dielectric film without a significant decrease in the thickness of an IDT when the dielectric film is formed by deposition and without deterioration of electrical characteristics. The method includes the steps of forming an IDT on a piezoelectric substrate, forming a lower dielectric film so as to cover the IDT, conducting a planarizing step so as to smooth the rough surface of the lower dielectric film, and forming an upper dielectric film so as to cover the lower dielectric film of which the rough surface is smoothed.

Abstract: A boundary acoustic wave device includes a first medium, a second medium, and an IDT electrode disposed at an interface between the first medium and the second medium, the IDT electrode having an Au layer defining a main electrode layer, wherein a Ni layer is laminated so as to contact at least one surface of the Au layer, and a portion of Ni defining the Ni layer is diffused from the Ni layer side surface of the Au layer toward the inside of the Au layer.

Abstract: A boundary acoustic wave device includes a first medium, a second medium, and an IDT electrode disposed at an interface between the first medium and the second medium, the IDT electrode having an Au layer defining a main electrode layer, wherein a Ni layer is laminated so as to contact at least one surface of the Au layer, and a portion of Ni defining the Ni layer is diffused from the Ni layer side surface of the Au layer toward the inside of the Au layer.

Abstract: A surface acoustic wave device has superior electrical power resistance that is obtained by improving stress migration resistance of electrodes. In order to form at least one electrode, for example, on a ? rotation Y-cut (?=36° to 42°) LiTaO3 piezoelectric substrate, an underlying electrode layer including Ti or Cr as a primary component is formed, and an Al electrode layer including Al as a primary component is then formed on this underlying electrode layer. The Al electrode layer is an oriented film grown by epitaxial growth and is also a polycrystalline thin film having a twin structure in which a diffraction pattern observed in an X-ray diffraction pole figure has a plurality of symmetry centers.

Abstract: A surface acoustic wave device has superior electrical power resistance that is obtained by improving stress migration resistance of electrodes. In order to form at least one electrode, for example, on a ? rotation Y-cut (?=36° to 42°) LiTaO3 piezoelectric substrate, an underlying electrode layer including Ti or Cr as a primary component is formed, and an Al electrode layer including Al as a primary component is then formed on this underlying electrode layer. The Al electrode layer is an oriented film grown by epitaxial growth and is also a polycrystalline thin film having a twin structure in which a diffraction pattern observed in an X-ray diffraction pole figure has a plurality of symmetry centers.

Abstract: A surface acoustic wave device has superior electrical power resistance that is obtained by improving stress migration resistance of electrodes. In order to form at least one electrode, for example, on a &thgr; rotation Y-cut (&thgr;=36° to 42°) LiTaO3 piezoelectric substrate, an underlying electrode layer including Ti or Cr as a primary component is formed, and an Al electrode layer including Al as a primary component is then formed on this underlying electrode layer. The Al electrode layer is an oriented film grown by epitaxial growth and is also a polycrystalline thin film having a twin structure in which a diffraction pattern observed in an X-ray diffraction pole figure has a plurality of symmetry centers.

Abstract: A surface acoustic wave device includes a piezoelectric substrate made of a LiNO3 or LiTaO3 single crystal, and an electrode having power endurance. After a damaged layer formed on a surface of the piezoelectric substrate is removed, an under-electrode layer including at least one of Ti and Cr as a main component is formed by a vacuum deposition process at a temperature of about 100° C. or less, and an Al electrode layer including Al or an Al main component is then formed on the under-electrode layer. The Al electrode layer has a twin crystal structure in which the Al crystal is oriented in a desired direction such that the (111) crystal plane of Al substantially coincides with the Z crystal direction of the piezoelectric substrate.

Abstract: A surface acoustic wave device has superior electrical power resistance that is obtained by improving stress migration resistance of electrodes. In order to form at least one electrode, for example, on a &thgr; rotation Y-cut (&thgr;=36° to 42°) LiTaO3 piezoelectric substrate, an underlying electrode layer including Ti or Cr as a primary component is formed, and an Al electrode layer including Al as a primary component is then formed on this underlying electrode layer. The Al electrode layer is an oriented film grown by epitaxial growth and is also a polycrystalline thin film having a twin structure in which a diffraction pattern observed in an X-ray diffraction pole figure has a plurality of symmetry centers.

Abstract: A surface acoustic wave device includes a piezoelectric substrate made of a LiNO3 or LiTaO3 single crystal, and an electrode having excellent power endurance. After a damaged layer formed on a surface of the piezoelectric substrate is removed, an under-electrode layer including at least one of Ti and Cr as a main component is formed by a vacuum deposition process at a temperature of about 100° C. or less, and an Al electrode layer including Al or an Al main component is then formed on the under-electrode layer. The Al electrode layer has a twin crystal structure in which the Al crystal is oriented in a desired direction such that the (111) crystal plane of Al substantially coincides with the Z crystal direction of the piezoelectric substrate.