Surface acoustic wave device, surface acoustic wave filter and antenna duplexer using the same, and electronic equipment using the same

A method of manufacturing a surface acoustic wave device, the surface acoustic wave device comprising:

• a substrate including lithium niobate;
• a IDT being provided on an upper surface of the substrate and including a plurality of electrode fingers;
• and
• a protective film covering the IDT and having an uneven shape on an upper surface thereof,
• wherein the method satisfies a following first relations,
• p1+p2=p, and h/(2×p)≧4.5%
• when a pitch width of one pitch of the IDT is p,
• a width of one of the electrode fingers is p1,
• a width between the electrode fingers is p2, and
• a thickness from the surface of the substrate to an upper part of the IDT in an equivalent thickness of aluminum is h;
• a shape of the uneven shape is controlled in accordance with an electrode film thickness;
• and
• the method satisfies a following second relations,
• L1+L2=L, L1≦p1, and L2≧p2
• when a pitch width of one pitch in the uneven shape is L;
• a width of one pitch of a convex portion in the uneven shape is L1, and
• a width of one pitch of a concave portion in the uneven shape is L2, and
• wherein the surface acoustic wave device satisfying the first relations and the second relations is produced by using a bias sputtering method.