Single-Wafer Combinatorial Optimization of Border Rings for Bulk Acoustic Wave Filters

Optimization of bulk acoustic wave (BAW) resonator border ring (BR) thicknesses and widths has traditionally been done using multi-wafer splits, often in combination with modeling techniques. Here we describe a single-wafer, two-factor experimental design with 21 distinct experimental regions where we employed custom ion trim and photoresist exposure procedures to optimize BR thickness and width. This resulted in a methodology for optimizing device performance in a manner that reduces the time and cost compared to traditional methods. Though we applied this experimental design to investigating the impact of BR thickness and width on radio frequency BAW filter passband performance, it is generalizable, thereby enabling single-wafer multi-factor experimental designs across an array of device components. 2024-0039