Voltage-dependent capacitance behavior and underlying mechanisms in metal–insulator–metal capacitors with Al 2 O 3 –ZrO 2 –SiO 2 nano-laminates

Nano-laminates consisting of high-permittivity dielectrics and SiO 2 have been extensively studied for radio frequency metal–insulator–metal (MIM) capacitors because of their superior voltage linearity and low leakage current. However, there are no reports on the capacitance–voltage ( C–V ) characteristics at a high sweep voltage range. In this work, an interesting variation in the voltage-dependent capacitance that forms a ‘ ω ’-like shape is demonstrated for the MIM capacitors with Al 2 O 3 /ZrO 2 /SiO 2 nano-laminates. As the thickness ratio of the SiO 2 film to the total insulator increases to around 0.15, the C–V curve changes from an upward parabolic shape to a ‘ ω ’ shape. This can be explained based on the competition between the orientation polarization from SiO 2 and the electrode polarization from Al 2 O 3 and ZrO 2 . When the SiO 2 film is very thin, the electrode polarization dominates in the MIM capacitor, generating a positive curvature C – V curve. When the thickness of SiO 2 is increased, the orientation polarization is enhanced and thus both polarizations are operating in the MIM capacitors. This leads to the appearance of a multiple domain C – V curve containing positive and negative curvatures. Therefore, good consistency between the experimental results and the theoretical simulations is demonstrated. Such voltage-dependent capacitance behavior is not determined by the stack structure of the insulator, measurement frequency and oscillator voltage, but by the thickness ratio of the SiO 2 film to the whole insulator. These findings are helpful to engineer MIM capacitors with good voltage linearity.