Electrostatic scattering of ionic species in low pressure sputtering of Ti and TiN

A technique of sputtering with low pressures and large substrate to target distances (long throw) has been studied with a view of applying the technique to the deposition of titanium and titanium nitride on high aspect ratio topographies. The angular distributions of the sputtered species produced by most sputtering systems are broad and therefore unsuitable for application to via filling in ultralarge scale integration or even to lift‐off patterning in very‐large scale integration. In our work, progressive reduction in the pressure to 0.013 Pa (0.1 m Torr) while reducing the size of the planar magnetron (to 50 mm diam), was made possible by injecting electrons and ionized Ar by means of a secondary hollow cathode source. These reductions in pressure and magnetron size have greatly narrowed the incident angular distribution of the sputtered species at the substrate. However, we believe that a component of the sputtered species is electrostatically scattered near the substrate. This is important because ma...