Surface acoustic wave filter

Abstract

A surface acoustic wave (SAW) filter and its surface treatment method are disclosed. The surface treatment method includes a step A and a step B. Step A involves ion bombardment of the surface of a piezoelectric substrate. Step B involves forming a finger transducer on the ion-bombarded surface of the piezoelectric substrate. By ion bombarding the surface of the piezoelectric substrate, impurities can be removed. The subsequent formation of the finger transducer on the ion-bombarded surface reduces the contact resistance between the piezoelectric substrate and the finger transducer, thereby reducing insertion loss.

Claims

1. A surface acoustic wave filter, comprising: a piezoelectric substrate including an ion-bombarded surface, the surface being roughened; a finger transducer formed on the roughened surface of the piezoelectric substrate; a dielectric layer formed on the piezoelectric substrate and the finger transducer; a first electrode covering the dielectric layer and electrically connected to the finger transducer; a second electrode spaced apart from the first electrode and electrically connected to the finger transducer; and a protective layer covering the piezoelectric substrate, the finger transducer, the first electrode, and the second electrode.

Images