Patent ID: 10924086

Abstract:
A device including a piezoelectric substrate, an interdigital transducer (IDT), and an antireflective structure is disclosed herein. The piezoelectric substrate has a front-side surface and a smoothed back-side surface. The IDT is on the front-side surface of the piezoelectric substrate. The antireflective structure is over at least a portion of the smoothed back-side surface of the piezoelectric substrate. By having the antireflective structure on at least a portion of the smoothed back-side surface of the piezoelectric substrate, reflection of spurious bulk acoustic waves toward the front-side surface of the piezoelectric substrate can be reduced and/or eliminated to lessen interference with surface acoustic waves. The reduction and/or elimination of spurious bulk acoustic waves allows the device to forego conventional roughening of the back-side surface of the piezoelectric substrate, thereby reducing fractures at the back-side surface and allowing for singulation techniques capable of producing smaller die sizes.