Study On Preparation Process And Properties Of HfO₂ Thin Films

It is commonly known that Hafnium oxide (HfO2) thin films are widely used in the fields of optical system, integrated circuit and protective coating. This is because of its superior properties such as transparent spectral range from the infrared to the ultraviolet, excellent laser induced damage threshold(LIDT), high permittivity, good thermodynamic stability and chemical stability. Meanwhile, magnetron sputtering provides some advantages in controlling the microstructure and composition of the films. So that, it has become one of the main method to prepare HfO2 films. However, how to prepare high purity, low defect density, low stress and good stability of HfO2 thin films by using magnetron sputtering method is still a hot research problem in recent years.HfO2 films are deposited by different magnetron sputtering of DC and RF. Orthogonal experiment is used to study the target power, target-substrate distance and argon oxygen ratio (Ar:O2) which effect on films properties. The effect of the biggest impact of the factors that is Ar:O2 on the thin films structure, optical property and mechanical propery are analyzed. At the same time the thesis anaylzes the intimate relationship between microstructure and property of HfO2 films. With the problem of HF metal sputtering rate is higher than O, Hf element reaction rate in the process of HfO2 films are fabricated by magnetron sputtering, the thesis determine the best parameters of substrate temperature and negative bias for improving the properties of HfO2 films. Finally, the optimum parameters in the preparation process are obtainedIn order to further improve the properties of the HfO2 films, the films are annealing and treated by ion beam. The thesis study the change rules of thickness, crystallization behavior, transmissivity, hardness, elasticity modulus and LIDT of HfO2 films under the control of the parameters of annealing temperature, ion energy, ion beam density and ion beam treatment time. The result shows:as the annealing temperature is 900℃, the peak transmittance in the visible spectral range, hardness and elastic modulus of the films are 93.11%,10.61 GPa and 183.99GPa respectively. The LIDT of films is 15.32J/cm2 when the ion source beam voltage is 400V and treat time is 20min. It is indicated that the method of reactive magnetron sputtering and the corresponding post treatment could be used to prepare the high quality HfO2 films.