Conventionally, a capacitor structure in an integrated circuit may either be a flat parallel-plate capacitor structure or a trench capacitor structure. Capacitance per unit area for these flat parallel-plate capacitor structures or trench capacitor structures is based on dielectric thickness of the capacitor structures. This is unlike a metal-oxide-metal (MOM) finger capacitor structure where the capacitances depend on the overlapping conductive segments.
The MOM finger capacitor structure is a common circuit component within an integrated circuit. The MOM finger capacitor structure can be used within a loop filter circuit, an inductance-capacitance voltage controller oscillator (LCVCO) circuit, an analog-to-digital converter (ADC) circuit, a digital-to-analog converter (DAC) circuit, a power supply decoupling circuit or a ground decoupling circuit. Most of these circuits require a small-sized yet a precisely-designed MOM finger capacitor structure (e.g., the ADC circuit).
However, it is difficult to manufacture the small-sized yet precisely-designed MOM finger capacitor structure. One of the reasons is due to backend of the line (BEOL) process variations. The other reason is the capacitances requirement for a particular circuit may vary as a manufacturing process matures. The abovementioned reasons coupled with the limitations arising from new generation processes, especially where each metal layer may have conductive segments routed in a single direction only, make it difficult to manufacture the MOM finger capacitor structure within an integrated circuit.