A New Design of Trapezoidal Interdigital Capacitor with High Q or Capacitance Using BCB-based MEMS Process

This paper presents a novel design of trapezoidal interdigital capacitors using BCB-based MEMS process. The proposed designs improve the capacitance density and Q value under high-frequency conditions. The electrode and dielectric losses are calculated by HFSS, which explain the Q value difference between the trapezoidal and classic interdigital capacitors. The electrode surface current density analyses further reveal the mechanisms behind the loss characteristics. The stacked configuration can increase the capacitance and mitigate the Q value variation related to electrode shape despite the Q value reduction compared with single-layer designs. This work provides a feasible approach to optimizing interdigital capacitors for specific RF applications, balancing capacitance density and Q factor through electrode geometric changes.