High reliability metal insulator metal capacitors for silicon germanium analog applications

In this work, a novel "planar" metal-insulator-metal capacitor (MIMCAP) process is introduced, integrated in a Silicon Germanium (SiGe) HBT process, which has excellent yield, reliability and repeatability. The MIMCAP was characterized for DC and AC parametrics, and stressed at elevated biases and temperatures to assess reliability. An equivalent circuit and SPICE model were generated, and good agreement was found between the simulated and measured characteristics. A MIMCAP with high device/bottom plate capacitance ratio, excellent yield and reliability are critical needs in high quality passives for the fabrication of advanced analog mixed/signal circuits with on-chip components. In collaboration with Analog Devices, SiGe HBT voltage controlled oscillators (VCO) circuits were designed with both MIMCAP and substrate capacitor controls to demonstrate the leverage of this novel passive element.