Substrate Effects on Resonant Frequency of Silicon-Based RF On-Chip MIM Capacitor

This brief presents an analytical model that describes a silicon-based RF on-chip metal-insulator-metal (MIM) capacitor including the parasitics originating from its coupling with backend intermetal dielectric (IMD) scheme and the substrate. Results show that the resonant frequency f_re depends on the intrinsic capacitance, inductance, and substrate effects of the MIM. The model and f_re formula are verified experimentally for several types of MIM capacitors (i.e., high kappa and Si₃N₄ based) integrated on different IMDs (e.g., undoped glass and low kappa). The results also show that for a given C_MIM, if the capacitance density is increased further so that the area is shrunk, and the inductances are reduced to a level that is comparable to the substrate effects from item epsiv₀epsiv_rrho_Si h_eff|SiR₂/h_eff|IMD, then further f_re improvement could be limited