Packaged acoustic wave devices with multilayer piezoelectric substrate

A method of making a packaged acoustic wave component, comprising:

• forming an acoustic wave device including forming or providing a substrate, forming or providing a piezoelectric structure over at least a portion of the substrate, and forming or providing an electrode structure disposed over the piezoelectric structure;
• providing a polymer structure lateral portion over the substrate or over the piezoelectric structure;
• forming or providing a polymer structure comprising a polymer structure wall portion and a polymer structure roof portion configured to form a cavity over the electrode structure;
• forming or providing a metal structure disposed over the polymer structure;
• and
• forming a buffer coating disposed over the metal structure,
• the polymer structure having a polymer structure lateral portion sandwiched between the substrate, a dielectric layer disposed on the substrate, or the piezoelectric structure on one side, and the metal structure and the buffer coating on the other side.