Title :
Acoustically-induced migration of thin film electrodes in SAW-resonator-coupled filters
Author :
Shibagaki, N. ; Asai, K. ; Tabuchi, T. ; Hirashima, T. ; Hikita, M.
Author_Institution :
Hitachi Ltd., Tokyo, Japan
Abstract :
The aging characteristics of recently developed SAW-resonator-coupled filters are discussed. The rejection level of the filter was decreased by applying power. This result means that the Q -factor of the surface acoustic wave (SAW) resonator decreases with applied power. This change was studied by means of resistivity measurement and microscopic observation. It was found that the resistivity of the thin film increases by stress-induced migration. The decrease of rejection level and the decrease of the resonator´s Q -factor are explained by the measurement resistivity. Voids and hillocks were observed on thin-film electrodes. These observations also support the resistivity increase caused by stress-induced migration. It was seen that the formation of voids and hillocks induced the resistivity increase in thin-film electrodes. It is concluded that the cause of electrical characteristics change is the resistivity increase in the thin-film electrodes
Keywords :
Q-factor; acoustic resonators; scanning electron microscope examination of materials; scanning tunnelling microscopy; surface acoustic wave filters; voids (solid); Q-factor; SAW-resonator-coupled filters; SEM; STM; acoustically induced migration; aging characteristics; hillocks; microscopic observation; rejection level; resistivity; stress-induced migration; surface acoustic wave; thin film electrodes; voids; Acoustic waves; Aging; Conductivity measurement; Electric variables; Electrodes; Microscopy; Q measurement; Resonator filters; Surface acoustic waves; Transistors;
Conference_Titel :
Ultrasonics Symposium, 1991. Proceedings., IEEE 1991
Conference_Location :
Orlando, FL
DOI :
10.1109/ULTSYM.1991.234203
