Characterizing Voltage Linearity and Leakage Current of High Density MIM Capacitors

It was found that the quadratic voltage coefficient of the capacitance (VCC) of Al₂O₃-based metal-insulator-metal (MIM) capacitors is inversely proportional to the square of the insulator thickness, i.e., ~t^-2, whereas HfO₂-based MIM capacitors exhibit the inverse cube relationship, i.e., ~t^-3. Using each of their voltage linearity characteristics in combination with the VCC calculation method, the quadratic VCC of Al₂O₃/HfC₂/Al₂O₃ (A/H/A)-structured MIM capacitors, with various thickness ratios of the Al₂O₃ and HfO₂ insulators, could be well estimated. A large portion of the HfO₂ insulators in the A/H/A structures improved the voltage linearity of the MIM capacitors, whereas it deteriorated the dielectric breakdown and the leakage current characteristics.