Fabrication and Integration of Ultrathin, High-Density, High-Frequency Ta Capacitors on Silicon for Power Modules

This paper demonstrates silicon-integrated, thinfilm, high-density tantalum capacitors for integrated power modules. The capacitors in form-factors of less than 75 mu m showed stable capacitance densities of more than 0.3 mu F/mm(2) with leakage of less than 0.1 mu A/mu F at 3 V. To the best of authors' knowledge, this is the highest capacitance density reported till date at the mentioned form-factors. Furthermore, these capacitors are integrated directly above the active silicon, enabling shorter interconnection path with lower system parasitics, leading to higher switching frequencies and lower losses. These ultra-miniaturized, substrate-compatible tantalum capacitors, thus, address the strategic need for highly-efficient, ultra-miniaturized power modules.