Plasma processes often go beyond the primary objectives focused on the substrate, or targeted materials. For instance, sputtered materials deposit on surfaces other than the substrate, and plasma deposition extends to the walls of the reactor. In the process of plasma polymerization, or plasma chemical vapor deposition (PCVD), every surface (not just the substrate surface) participates in the overall plasma deposition process. Consequently the chemical and physical natures of all surfaces within a reactor are very important factors that determine the fate of the PCVD process. The materials deposited on the wall surface (wall contaminants) are created in the previous run in a batch operation of PCVD. In a sequential plasma process, where plasma polymerization of trimethylsilane (TMS) was followed by plasma polymerization of hexafluoroethane (HFE), F-containing oligomers (low molecular weight compounds), created during the plasma polymerization of HFE in the previous ran, remain on surfaces in the reactor. The wall contaminants were found to migrate to the new substrate (aluminum alloy) surface in the subsequent run upon the evacuation of the reactor. If an O-2 plasma treatment is applied, F-containing organic compounds chemisorbed on the new substrate surface are converted to F-containing inorganic compounds, which decreases the plasma-ablatable F on the surface. If no O-2 plasma treatment is applied, the F-containing organic compounds are exposed to the environment of the TMS plasma. From the viewpoint of the sequence of plasma processes, a new HFE/TMS sequence is created without the O-2 plasma treatment. The HFE/TMS system (reversed order to the normal cycle) causes adhesion failure at the interface between the plasma polymers and the aluminum alloys, whereas the TMS/HFE system yields good adhesion of plasma deposited layers to the substrate and provides superior adhesion of a primer applied on the plasma polymer coating. This difference was created by the difference in handling of the wall contaminants.