A low-cost approach to high-k thinfilm decoupling capacitors on silicon and glass interposers

This paper demonstrates a novel low-cost thinfilm capacitor technology on silicon and glass interposers for decoupling in high-speed digital systems. Silicon interposers with thinfilm capacitors have been demonstrated before, but these technologies have not been widely adapted because of the high cost of platinum electrodes and their incompatibility with packaging infrastructure. Thinfilm capacitors with alternative package-compatible low-cost electrodes such as copper and nickel were unsuccessful because of the processing challenges on Si substrates that arise as a result of high inter-diffusion and film stress. A new class of solutions was explored to address the challenges on silicon interposer substrates. Glass-compatible crystallization processes were studied to achieve high capacitance densities. Nickel electrodes showed a capacitance density of 1.1 μF/cm², 2-3× higher than those with alternative glass-compatible thinfilm capacitor technologies.