Investigation of thin films for fabrication of Nb/AlN/NbN tunnel junctions and microstrip lines of NbTiN-SiO2-Al

The surface of thin films of Nb, Al, NbTiN, SiO2, Al2O3 is investigated in this work. These films are necessary for the fabrication of high-sensitive devices of THz range. The fabrication processes of such devices are described briefly. All films were fabricated using a Kurt J. Lesker magnetron sputtering system. The study of the film surface roughness was carried out using a Bruker Ikon atomic force microscope. The surface quality of films is determined not only deposition mode, but plasma etching process also. The best values of the root-mean-square deviation of the surface profile Rq = 2 nm were obtained for the used NbTiN film with a thickness of 325 nm. Thin Al-layers that is used for tunnel barrier formation is studied. It is shown than Al films with a thickness of more than 6 nm are already continuous. The surface roughness of the single-layer and multilayer films has been studied.