Very thin plasma enhanced chemical vapor deposition (PECVD) titanium (Ti) of 6 +/- 1 nm was characterized on doped unstructured and structured Si substrate. Based on the current state of the art, we utilized the Design of Experiment (DoE) methodology, considering selected responses and factors of the Ti deposition and post annealing. This paper provides approaches on how to apply PECVD for unstructured silicon and structures with increasing aspect ratios. The derived process for unstructured wafers yields low resistivity at a Ti film thickness of approximately 7 nm. An uniform filling inside a test structure was achieved with a low process temperature of 590 degrees C, an increasing pressure and TiCl4-flow as well as a post rapid temperature anneal process (RTP) at medium temperature and time. The dispersion of the measured total resistance increases over the different trench distances at lower process pressure, higher power, and higher RTP. In contrast to the reference process configuration, the formed TiSi2 is smaller-grained and more uniform within the entire test structure. Consequently, leveraging DoE for the used test structure geometries allows the evaluation and optimization of silicide and its properties as a function of contact geometry and of Si doping.