Fabrication technology of high frequency and high power durable surface acoustic wave devices for mobile radio communications

Addition of Ti, Ge and Zn to sputtered Al electrodes is investigated to obtain both high power durability and fine dimension control in high frequency surface acoustic wave (SAW) devices. Ti is more effective than Ce, Zn and conventional Cu. Improvement of electrode durability to SAW power is related to the grain refinement and static stress incorporated by addition of Ti, Ce, Cu and by the sputter deposition. In Ti added Al, dry etching (reactive ion etching: RIE) with BCl containing gases can be more easily performed than Cu added ones. By using the RIE and dyed W posi-type resist, line-width deviation (3σ) of 1.2 μm electrodes can be decreased to the small value of 95 nm, a value which is 40% of that in conventional wet etched ones