Coating the inner walls of tubes with TiN films by reactive sputtering

It is possible to achieve a homogenous coating of the inner walls of tubes by sputter deposition. For this purpose a conical sputter target is moved through the tube parallel to its axis while an ion beam enters the tube along its axis, impinges onto the target and sputters material onto the tube inner wall. But so far only monatomic coatings were performed with this technique. To improve the mechanical properties of tubes TiN films were deposited by reactive sputtering. Therefore a Ti sputter target is used, the NZ reactive gas is delivered into the tube by a nozzle. The topography of the films is dominated by a ripple structure with the wave vector perpendicular to the tubes length axis. The development of the ripples is discussed in terms of scattered Ar projectiles which impinge onto the substrate as well as the deposited film under grazing incidence angles. Results of RBS, ERD, AFM, and hardness measurements are shown.