Ultra-thin high density capacitors for advanced packaging solutions

The growing demand on small system solutions is driving the compression of many functions into small package outline. This requires sophisticated solutions to avoid external circuitry area when integrating passive components. Moreover, decoupling capacitors need to be placed as close as possible to the active circuits in order to suppress cross-coupling between different power planes efficiently. In our paper we present the concept, fabrication and characterization results of ultra-thin silicon capacitors that can be integrated into chip package or embedded in PCB. High capacitance densities are achieved by using high-k materials as dielectric supporting a broad application range from RF-filtering to decoupling and energy buffering. Based on characterization results of voltage and temperature characteristics it is shown that this concept offers good electrical properties and linearity compared to conventional ceramic capacitors, like MLCC. Further, potential integration options are discussed showing the way to even thinner substrates down to 30 μm.