Study On The Preparation Of HfO₂ Nano-films By Reactive Magne- Tron Sputtering And The Integration Of Capacitor

With the rapid development of integrated circuits and the upgrading of semiconductor materials technology, higher requirements have been put forward for performance of the MOS device gate dielectric materials, and the conventional SiO2 gate oxide layer has been not suitable for process requirements gradually. Currently high-& oxide materials has become a hot research direction in this field. HfO2 thin film which has excellent properties and good compatibility with silicon integrated circuit, has become the most promising gate dielectric material. Furthermore, a recent study has found that HfO2-based thin films also have ferroelectric properties after doping, and HfO2-based ferroelectric thin films have achieved excellent integration with silicon-based semiconductor compared with conventional ferroelectric materials,, this discovery will greatly promote replace traditional ferroelectric material and break through the barriers for the application of Ferroelectric RAM.In this paper, the HfO2-based film has been prepared by reactive magnetron sputtering with pure hafnium metal target innvatively. Starting with the preparation of pure non-doped HfO2, the step instrument, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM) and other analytical tools have been applied to determine the thickness, composition, effects of process parameters on the surface morphology of the films, which laid the foundation for doping. Pure yttrium metal target connected with RF power have been used to achieve the preparation of Y-doped HfO2 films, and X-ray reflectivity, X-ray photoelectron spectroscopy, X-ray diffraction have been employed to determine the thickness, composition and crystal structure of the films.In order to complete the integration of capacitor, the preparation of the top electrode has been investigated in this paper. The first method was to design the mask based on the electrical measurement, and Au, Pt, then make a representation and comparison among Au, Pt and TiN electrode materials of the growth rate and resistivity, finally electrical properties were measured after the completion of the integrated thin film capacitor.The results show that high quality Y-doped HfO2 films have been successfully deposited on Si substrates by the RF magnetron reactive sputtering system. Growth rate of the films obtained at room temperature was about 0.6nm/min, the XPS spectra showed precise relationship between Y% and the power of target, and by dividing the peak illustrated Y doping form of Y2O3. By comparison, titanium nitride as the top electrode material of capacitor structure was choosen in this paper because of its stable and controllable process, high deposition efficiency and excellent resistivity. Electrical tests showed the initial dielectric constant was small and the leakage current was not ideal. After analysis of the reasons that may arise, we attempted to reduce the working pressure. Results showed density and thickness of films were improved, and the electrical properties were developed significantly according to the XRR analysis.