Surface acoustic wave device with a layered conductive film and method of producing the same

In a surface acoustic wave filter comprising a piezoelectric substrate, a plurality of electrode fingers formed on the piezoelectric substrate, a bus bar connecting the electrode fingers in common, and an electrode pad connected to the bus bar, a surface acoustic wave filter characterized in that said electrode fingers, said bus bar, and said electrode pad are each formed by alternately stacking a conductive layer consisting mainly of aluminum and an intermediate layer consisting mainly of any other metal than aluminum, and said bus bar is provided with regions in which said conductive layers are different in number.

In a surface acoustic wave filter comprising a piezoelectric substrate and surface acoustic wave filter elements having at least input and output electrodes and formed on said piezoelectric substrate, a composite surface acoustic wave filter characterized in that a plurality of surface acoustic wave filter elements are provided on the same surface of said piezoelectric substrate, a conductive film of at least one first surface acoustic wave filter element is composed of two or more layers of different compositions, a conductive film of at least one second surface acoustic wave filter element is composed of one layer or two or more layers of different compositions and is thinner than the conductive film of said first surface acoustic wave filter element, and the composition of the uppermost layer of the conductive film is different from that of said first surface acoustic wave filter element.

In a surface acoustic wave filter comprising a piezoelectric substrate and surface acoustic wave filter elements having at least input and output electrodes and formed on said piezoelectric substrate, a surface acoustic wave filter characterized in that a plurality of surface acoustic wave filter elements are provided on the same surface of said piezoelectric substrate, a conductive film of at least one first surface acoustic wave filter element is composed of a plurality of metallic layers including an uppermost layer formed of or consisting mainly of aluminum and a layer thereunder consisting mainly of aluminum and tantalum, a conductive film of at least one second surface acoustic wave filter element is a metallic layer including an uppermost layer formed of an alloy consisting mainly of aluminum and tantalum and having a thickness different from that of said first surface acoustic wave filter element.

In a surface acoustic wave filter comprising a piezoelectric substrate, a plurality of electrode fingers formed of a plurality of metallic layers on the piezoelectric substrate, a bus bar formed of a plurality of metallic layers on said piezoelectric substrate and connecting the electrode fingers in common, and an electrode pad formed of a plurality of metallic layers on said piezoelectric substrate and connected to the bus bar, a surface acoustic wave filter characterized in that said electrode-fingers and said electrode pad are different in film thickness arid surface layer metal composition, and the same metal composition of the surface layer of said electrode fingers is used for intermediate layers among the metallic layers constituting the electrode pad.