Effect of oxide and interface traps on electrical characteristics of post-deposition annealed HfSiO4/n-Si structures
This study presents detailed results on the modifications in chemical composition, defective bonds, crystal properties based on x-ray photoelectron spectroscopy (XPS) depth profiles and x-ray diffraction of post-deposition annealed HfSiO4/Si structure. It also leads to a link to defect centers and their effect on the electrical characteristics of MOS capacitors. The HfSiO4 films were deposited on n-Si wafers by RF magnetron sputtering and annealed at room temperature (RT), 300 °C, 700 °C, 900 °C, 1100 °C under N2 ambient. That the atomic concentration values of each element in the oxide did not change significantly depending on the annealing temperature showed that the film was deposited with high homogeneity. It was determined that the shift direction of the binding energies of Hf 4f and O 1s XPS spectra were related to the bonding preference of oxygen rather than its concentration. The increase in Hf–M and Hf–Si oxygen defective bonds decreased the binding energy of the XPS spectra. It was determined from the XPS analyses of amorphous films that Hf–Si and Si–Si oxygen defective bonds may cause the positive charge trapping, resulting in the highest negative charge trapping/positive effective oxide charge density ( Qeff ) in the 300 °C-MOS capacitor. It was determined that Hf–Hf oxygen defective bonds may be the precursors of negative charge trapping. Interface states only contributed to the dielectric constant (k) in the RT-MOS capacitor. The ΦB (barrier height) values showed that the efficiency of acceptor-like and donor-like interface states changes depending on the frequency.