Effect of Heat Treatment on Zirconium Oxide High-k Gate Dielectric in Silicon-Based Metal Oxide Semiconductor Capacitors

Herein, zirconia thin films are successfully prepared on silicon substrates using the sol–gel method, and the microstructure, optical, and electrical properties of zirconia high- k gate dielectric films are analyzed at different annealing temperatures. X-ray diffraction results show that ZrO 2 films crystallize above 500 °C and the grain size increases with the increase of annealing temperature; X-ray photoelectron spectroscopy analysis confirms that metal–oxygen bonds can be effectively formed and defects in the films are eliminated by annealing treatment, with significant changes in the valence band shift (Δ E v ) and conduction band shift (Δ E c ) with increasing annealing temperature. Analysis of the optical properties of the films by UV-Vis confirms that all zirconia films have high transmittance, with the bandgap increasing from 5.54 to 5.74 eV with increasing annealing temperature. Atomic force microscope and field emission scanning electron microscope show that the film quality is better and the root mean square roughness of the zirconia films increases from 0.551 to 1.190 nm and the film thickness decreases from 176.19 to 58.73 nm with increasing annealing temperature. Electrical performance tests show that proper annealing is effective in improving electrical properties, such as obtaining a larger dielectric constant ( k ) and a lower leakage current density.