RESUMEN
Gas flow sputtering is a sputter deposition method that enables soft and high-rate deposition even for oxides or nitrides at high pressure (in the mbar range). A unipolar pulse generator with adjustable reverse voltage was used to optimize thin film growth by the hollow cathode gas flow sputtering system. In this regard, we describe our laboratory Gas Flow Sputtering (GFS) deposition system, which has been recently assembled at the Technical University of Berlin. Its technical facilities and suitability for various technological tasks are explored. The first experimental efforts are presented by the example of TiOx films on glass substrates obtained at various deposition conditions with forced Argon flow. The influence of pulsing parameters, power, and oxygen gas flow on the plasma generated is studied. The films were characterized by ellipsometry, scanning electron microscopy, x-ray diffraction, and x-ray reflectivity. Optical Emission Spectroscopy (OES) was also used to characterize the remote plasma, and the substrate temperature was measured. The pulsing frequency (f) is a significant factor that provides additional substrate heating by about 100 °C when the plasma regime changes from f = 0 (DC) to 100 kHz. Such a change in frequency provides a significant increase in the OES signals of Ti and Ar neutrals as well as of Ti+ ions. With pulsed operation at high power, the GFS plasma is capable of heating the glass substrate to more than 400 °C within several minutes, which allows for crystalline anatase TiOx film deposition without external heating. For deposition below 200 °C substrate temperature, low power DC operation can be used.
RESUMEN
This work demonstrated the optimization of HiPIMS reactive magnetron sputtering of hafnium oxynitride (HfOxNy) thin films. During the optimization procedure, employing Taguchi orthogonal tables, the parameters of examined dielectric films were explored, utilizing optical methods (spectroscopic ellipsometry and refractometry), electrical characterization (C-V, I-V measurements of MOS structures), and structural investigation (AFM, XRD, XPS). The thermal stability of fabricated HfOxNy layers, up to 800 °C, was also investigated. The presented results demonstrated the correctness of the optimization methodology. The results also demonstrated the significant stability of hafnia-based layers at up to 800 °C. No electrical parameters or surface morphology deteriorations were demonstrated. The structural analysis revealed comparable electrical properties and significantly greater immunity to high-temperature treatment in HfOxNy layers formed using HiPIMS, as compared to those formed using the standard pulsed magnetron sputtering technique. The results presented in this study confirmed that the investigated hafnium oxynitride films, fabricated through the HiPIMS process, could potentially be used as a thermally-stable gate dielectric in self-aligned MOS structures and devices.
