Characterizing Voltage Linearity and Leakage Current of High Density Al2O3/HfO2/Al2O3 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., similar to t(-2), whereas HfO2-based MIM capacitors exhibit the inverse cube relationship, i.e., similar to t(-3). Using each of their voltage linearity characteristics in combination with the VCC calculation method, the quadratic VCC of Al2O3/HfO2/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.