Plasma-enhanced flexible metal-insulator-metal capacitor using high-k ZrO_2 film as gate dielectric with improved reliability

摘要

We demonstrate a new flexible metal-insulator-metal capacitor using 9.5-nm-thick ZrO_2 film on a plastic polyimide substrate based on a simple and low-cost sol-gel precursor spin-coating process. The surface morphology of the ZrO_2 film was investigated using scan electron microscope and atomic force microscope. The as-deposited ZrO_2 film under suitable treatment of oxygen (O_2) plasma and then subsequent annealing at 250 ℃ exhibits superior low leakage current density of 9.0 × 10~(-9)A/cm~2 at applied voltage of 5 V and maximum capacitance density of 13.3 fF/μm~2 at 1 MHz. The as-deposited sol-gel film was completely oxidized when we employed O_2 plasma at relatively low temperature and power (30 W), hence enhancing the electrical performance of the capacitor. The shift (Zr 3d from 184.1 eV to 184.64 eV) in X-ray photoelectron spectroscopy of the binding energy of the electrons towards higher binding energy; clearly indicates that the O_2 plasma reaction was most effective process for the complete oxidation of the sol-gel precursor at relatively low processing temperature.