Thin Sc0.2Al0.8N Film Based 15 GHz Wideband Filter: Towards mmWave Acoustic Filters

In this work, 200 mm wafer-level 15 GHz bulk acoustic wave (BAW) resonators and filters have been demonstrated based on 90 nm thin Sc
0.2
Al
0.8
N film. The fabricated resonators have achieved an effective coupling coefficient of ~15% and a quality factor of over 200. The fabricated filters have demonstrated an insertion loss of ~ 3.5 dB and fractional bandwidth of ~ 10%, which is the highest among the reported acoustic filters at this frequency range. Further, circuit models with area-dependent parameters and embedded parasitics have been developed and calibrated for filter design. The promising results indicate the possibility of ScAlN-based BAW technology going beyond 10 GHz towards mmWave frequency filtering.