US Patent 7301423 Surface acoustic wave element and manufacturing method thereof

A surface acoustic wave (SAW) element including a semiconductor substrate on which a semiconductor wiring region and a SAW region are formed alongside in a same plane, a metal wiring formed in the semiconductor wiring region, an insulating layer including the metal wiring and formed throughout on surfaces of the semiconductor wiring region and the SAW region, a most upper layer of the insulating layer formed so as to have a one flat surface throughout the semiconductor wiring region and the SAW region and a uniform thickness from an upper face of the semiconductor substrate, a piezoelectric layer formed on the most upper layer of the insulating layer and an inter digital transducer (IDT) formed on the piezoelectric layer in the SAW region.