surface wave filter

Abstract

Abstract PURPOSE:To eliminate defect of stage due to the bent of a substrate and defect of crystal (zinc oxide) by constituting a surface wave filter comprising of a comb line electrode, a piezoelectric material and an opposed electrode to one side of a glass substrate and providing the same piezoelectric material or a material having a thermal expansion coefficient close to the former material to the other side. CONSTITUTION:A zinc oxide thin film 2 is provided to one major plane of the glass substrate 1 by the sputtering or the like and an SiO2 film 3 is provided by the sputtering so as to avoid the zinc oxide thin film 2 from being etched at the post etching process. Then aluminum is vapor-deposited to the major plane of the front side, the aluminum-made comb line electrode 4 is provided by the photo lithography, the zinc oxide thin film 5 is provided on it by the sputtering, the aluminum opposed electrode 6 is vapor-deposited on it, then the zinc oxide on the pad electrode connected to the comb line electrode is removed finally by etching to complete the wafer. Since the zinc oxide thin films 2, 5 are formed on both sides of the glass substrate line this way, the difference of thermal expansion due to temperature change hardly takes place and the bent of the glass substrate is eliminated.

Inventors

• 👤 Junichi Inohara
• 👤 猪原　淳一

Bibliographic Details