THIN FILM ELASTIC WAVE DEVICE

• Main Author: EHATA YASUO
• Format: Patent
• Language: English
• Published: 09.04.1987
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS

PURPOSE:To prevent destruction or deformation of vibrating film due to internal stress by providing a polyimide group resin layer at least a part between a substrate and the vibrating film in a thin film elastic wave device where the vibrating film made of a piezoelectric thin film or the like is formed on the substrate. CONSTITUTION:The polyimide group resin film 2 is formed to the entire surface of an Si substrate 1. As the polyimide group resin, a PIQ (registered trade mark) is used and the PIQ pre-polymer liquid is coated by revolution by a spinner as the forming method of the resin film 2 and the film is baked to form the polyimide group resin film 2. An SiO2 film 4 is formed on the polyimide group resin film 2 and a lower electrode 5, a ZnO piezoelectric thin film 6, an upper electrode 7 and an SiO2 film 8 are formed in this order on the SiO2 film 4 by the sputtering method and the photo lithography method to form the vibrating film 9. Through the constitution above, the internal stress existing in the forming of the vibrating film 9 is relaxed by the elasticity of the polyimide group resin film 2 and destruction and deformation of the vibrating film 9 are reduced remarkably.