Plasma half dicing based on micro-loading effect for ultra-thin LiNbO3 plate wave devices on Si substrate

Ultra-wide band ladder filters with bandwidth of 41 to 51%, which fully cover the digital TV band, were fabricated using 0-th shear horizontal (SH0) mode plate wave in a (0°, 117.5-120°, 0°) LiNbO3 (LN) ultra-thin plate. A LN/cavity/Si wafer with a number of devices must be separated into chips as they can be mounted on a printed circuit board (PCB). When the wafer is separated using a dicing machine, the wafer must be protected from strong water showers because the LN ultra-thin plate of 0.5 to 0.6 μm thickness on a cavity is fragile. In this study, the authors developed a new separating (plasma half dicing) method using the micro-loading effect instead of the conventional blade dicing. This method enjoys the advantages of dry process, and no additional etching is needed, because the half dicing grooves are fabricated simultaneously with the device cavities. A chip filter mounted on a PCB after separation shows a good frequency characteristic similar to the one measured using a prober system before separation.