Abstract: Alumina is a high-k material that can be used in high-density MIM capacitors. It has a large bandgap and good thermal stability, and can effectively reduce leakage current. Alumina film was prepared by electron beam evaporation, and 10 nm Al₂O₃ metal-insulator-metal (MIM) capacitors were prepared. The capacitance-voltage (C-V) and current-voltage (I-V) characteristic curves of the MIM capacitors without annealing, 250 ℃, 300 ℃, and 350 ℃ nitrogen atmosphere annealing were tested. The experiment shows that 300 ℃ annealing can achieve the best comprehensive performance of MIM capacitors, reduces the secondary nonlinear voltage characteristic parameters by 85%, and the leakage current by more than two orders of magnitude, thereby effectively improving the electrical performance of thin film capacitors.