An acoustic resonator device is provided that includes a substrate; a piezoelectric layer on the substrate and including a diaphragm that extends across a cavity over the substrate; first and second interdigital transducer (IDT) busbars extending along opposing sides of the diaphragm; and first and second sets of IDT fingers extending from the first and second busbars, respectively, with the first and second sets of IDT fingers being interleaved and disposed on the diaphragm. Moreover, at least one interior angle between the first and second sets of IDT fingers and the respective first and second IDT busbars has a rounded corner disposed above the diaphragm in a thickness direction of the acoustic resonator device.