Acoustic wave device and electronic apparatus including same

An acoustic wave device comprising:

• a piezoelectric substrate having an upper surface;
• an interdigital transducer (IDT) electrode disposed above the upper surface of the piezoelectric substrate, the IDT electrode including a plurality of electrode fingers configured to excite a main acoustic wave;
• a first dielectric film made of an oxide and disposed above the upper surface of the piezoelectric substrate, covering the plurality of electrode fingers, and contacting the upper surface of the piezoelectric substrate at positions between adjacent electrode fingers of the plurality of electrode fingers;
• a second dielectric film made of a non-oxide and disposed on upper surfaces of the plurality of electrode fingers and between the first dielectric film and each of the plurality of electrode fingers;
• and
• a third dielectric film disposed between the piezoelectric substrate and each of the plurality of electrode fingers.

An acoustic wave device comprising:

• a piezoelectric substrate having an upper surface
• an interdigital transducer (IDT) electrode disposed above the upper surface of the piezoelectric substrate, the IDT electrode including a plurality of electrode fingers configured to excite a main acoustic wave;
• a first dielectric film made of an oxide and disposed above the upper surface of the piezoelectric substrate, the first dielectric film covering the plurality of electrode fingers;
• a second dielectric film made of a non-oxide and disposed on upper surfaces of the plurality of electrode fingers and between the first dielectric film and each of the plurality of electrode fingers;
• and
• a contiguous third dielectric film made of a non-oxide and disposed between the piezoelectric substrate and each of the plurality of electrode fingers beneath each of the plurality of electrode fingers.