Surface acoustic wave (SAW) device with one or more intermediate layers for self-heating improvement

A wireless device comprising:

• a radio frequency (RF) circuit;
• and
• a surface acoustic wave (SAW) filter coupled to the RF circuit, the SAW filter comprising:
• a piezoelectric layer;
• and
• an interdigital transducer (IDT) disposed above the piezoelectric layer and comprising a first electrode having a first busbar and a first plurality of fingers extending from the first busbar, wherein the first electrode comprises:
• a first copper layer disposed above the piezoelectric layer, wherein a grain size of the first copper layer is at most 120 nm;
• a first intermediate layer disposed above the first copper layer, the first intermediate layer comprising a different material than the first copper layer;
• and
• a second copper layer disposed above the first intermediate layer.

A method of fabricating a surface acoustic wave (SAW) device, the method comprising:

• forming an interdigital transducer (IDT) above a piezoelectric layer, wherein forming the IDT comprises forming a first electrode of the IDT, the first electrode having a first busbar and a first plurality of fingers extending from the first busbar, and wherein forming the first electrode comprises:
• forming a first copper layer above the piezoelectric layer;
• forming a first intermediate layer above the first copper layer, the first intermediate layer comprising a different material than the first copper layer, wherein the first intermediate layer has a thickness in a range of 0.1 to 5.0 nm;
• and
• forming a second copper layer above the first intermediate layer.

A surface acoustic wave (SAW) device comprising:

• a piezoelectric layer;
• and
• an interdigital transducer (IDT) disposed above the piezoelectric layer and comprising a first electrode having a first busbar and a first plurality of fingers extending from the first busbar, wherein the first electrode comprises:
• a first copper layer disposed above the piezoelectric layer;
• means for interrupting grain growth in the first copper layer, disposed above the first copper layer;
• a second copper layer disposed above the means for interrupting grain growth in the first copper layer;
• a silver layer disposed beneath the first copper layer;
• and
• an adhesion layer disposed beneath the silver layer.