Microcapacitors

Microcapacitors are miniature capacitors designed for integration into microelectronic systems. They provide local energy storage and fast charge-discharge cycles, serving decoupling, buffering, and signal integrity roles in integrated circuits and MEMS.

Most microcapacitors use interdigital electrode geometries on a chip or vertical architectures embedded in silicon. Common configurations include metal-insulator-metal (MIM) capacitors with thin dielectric films, and porous or high-surface-area carbon-based electrodes for higher capacitance per area. On-chip microcapacitors may be fabricated using CMOS-compatible processes such as lithography, chemical vapor deposition, atomic layer deposition, and sputtering to form electrodes and high-k dielectrics (for example Al2O3, HfO2) or ceramic dielectrics.

Materials considerations affect performance; high dielectric constant dielectrics maximize capacitance per area, while porous carbon, graphene, or carbon nanotube electrodes increase effective surface area. Channel and dielectric breakdown, leakage current, and parasitic inductance become important at small scales. Typical chip-scale microcapacitors exhibit capacitances from a few femto- to pico-farads for simple IDE structures, to several nanofarads in advanced vertical or stacked designs; voltage ratings range from a few volts to tens of volts, depending on dielectric.

Applications include decoupling and energy buffering in integrated circuits, RF front-ends, micro-sensors, and micro-energy storage for portable or implantable devices. In MEMS, microcapacitors can be integrated with sensors and actuators to improve noise performance and reliability.

Challenges include balancing miniaturization with energy density, reducing leakage and variability, and maintaining performance under temperature and mechanical stress. Ongoing research explores new materials, such as two-dimensional materials and nanostructured electrodes, and novel architectures to enhance capacitance while preserving CMOS compatibility.