Preparation Of High Hardness HfN_xO_y Films And Characterization Of Its Properties

HfO₂films are used in MOSFET as a substitute for SiO2films because of itshigh dielectric. As the separation technology of Zr and Hf advances, there are aplenty of research about Hf and its compounds, Hf application not only in thenuclear industry. HfO₂has shown many excellent properties, especially its goodtransmission from visible light to far infrared, it has the potential as a broad-bandantireflection film.This paper discussed the preparation methods of HfO₂, HfN and HfN_xO_ythinfilms, and determined the main process parameters in the process of filmspreparation. We prepared three groups of films in use of Reactive MagnetronSputtering methods, including HfO₂、HfN and HfN_xO_yfilms. X-ray photoelectronspectroscopy（XPS）, X-ray diffraction（XRD）, Nanoindentation and some othermethods were used to study the components, structure and hardness of the films.We studied the effect of the temperature and oxygen partial pressure on thecrystal structures of HfO₂films. The results showed that the HfO₂films areMonoclinic crystal structure at room temperature, there is also still some amorphousphase. Different oxygen partial pressure affect film crystalline structure. The higherthe temperature, the higher the degree of crystallinity of the film, and the trend ofthe preferential growth of the orientation （111）is more obvious. orientation. Onthis basis, we studied the structures of HfN_xO_yfilm through a variety of testmethods. GIXRD and the FTIR spectra analysis showed that the crystal structure ofthe the HfN_xO_ythin films were same as the HfO₂. XPS analysis revealed that thecontent of nitrogen in the HfN_xO_yfilms increased with the rise of nitrogen partialpressure. Surface profile measured the film thickness and radius of curvature, theresults showed that the deposition rate accelerated with the increase of nitrogenpartial pressure, the stress was a compressive stress state, and relatively low. HfO₂films’ hardness decrease with substrate temperature increasing, no higher than12GPa. All of the HfN_xO_yfilms’ hardness were greater than the hardness of12GPa,with increasing nitrogen content in the film, the hardness increases. When nitrogenand Hf atom ratio was0.756in the film, the film hardness was14.578GPa. It hadbeen proved that the incorporation of nitrogen making the film’s hardness greatlyimproved, but did not cause too much impact on the premise of the film crystalstructure. Elliptical polarization tests of the films showed that the refractive indexof HfN_xO_yfilms were1.9, same like the HfO₂films. We achieved the designrequirements that improving films’ hardness with no big affect on the optical properties of the films. In this paper, we did some basic research for application ofHfN_xO_yfilm as a kind of broad band transparent protective film.