Deposition of tantalum on steel by sputtering

Recent interest in tantalum deposition comes from two different applications. One is in microelectronics where thin tantalum films (\u3c 1 µm) are used as diffusion barrier layers for copper interconnects. The other involves its application as a material for corrosion and wear resistant coating on surfaces that are subjected to high stresses and harsh chemical and erosive environments. This thesis is a part of the investigation done at the Ion Beam and Thin Film Research Laboratory at NJIT to study the deposition conditions and properties of tantalum thin films. It includes the design and construction of Planar D.C. Magnetron Sputtering System and Cylindrical D.C. Magnetron Sputtering System for deposition on the planar and cylindrical surfaces of steel, respectively. The electrical characteristics of the cylindrical system were tested in a range of pressures and conditions for initiation and maintaining of discharge were established. The successful completion of planar magnetron system was demonstrated by deposition of tantalum films. The quality of these films has improved with refining of the deposition system and the process procedure. Tantalum films deposited in the planar magnetron sputtering system had thickness in the range of 4000 Å - 6000 Å. As a part of a pilot study, the films were analyzed using profilometry, Scanning Electron Microscope (SEM), X-ray Diffraction (XRD) and Rutherford Backscattering Techniques (RBS). The characteristics of the films were strongly dependent on the surface preparation and the residual gas in the deposition chamber. The presence of oxygen and water vapor in the residual gas results in films containing substantial amount of oxygen. Proper cleaning of steel substrates is essential for film integrity and adhesion. Surface preparation, including steel polishing, also influences crystallinity of the films. Typically, alpha and beta tantalum phases are present but there are indications that under controlled conditions pure alpha phase can be formed