SURFACE ACOUSTIC WAVE FILTER

摘要

PURPOSE:To obtain the desired characteristic of a surface acoustic wave filter by providing a dummy electrode adjacently to the outside of the utmost edge side of a roller creen type electrode, and obtaining the same etching state for each electrode and eliminating a tapered shape at the utmost edge side of the electrode. CONSTITUTION:A pair of dummy electrodes 14 having the same length as an aluminum utmost edge side electrode 13 of a roller screen form is provided adjacently to the outside of the electrode 13. Therefore the same etching state is secured for each roller screen type electrode in an etching mode for formation of electrodes since a resist mask is provided at the area equivalent to the electrode 14. This eliminate the difference of etching speed between the inside of the roller screen type electrode and the thickness direction of a metallic film of the side 15 immediately adjacent to the electrode 13. This causes no tapered shape of the electrode 13. Furthermore the characteristics can be obtained as designed since the electrode 14 has the same length as the electrode 13.