A method and apparatus for controlling the introduction of contaminates into a deposition chamber that occur naturally within the chamber components. The CVD chamber is "seasoned" with a protective layer after a dry clean operation and before a substrate is introduced into the chamber. The deposited seasoning layer has a lower diffusion rate for typical contaminants in relation to the chamber component materials and covers the chamber component, reducing the likelihood that the naturally occurring contaminants will interfere with subsequent processing steps. After deposition of the seasoning layer is complete, the chamber is used for one to n substrate deposition steps before being cleaned by another clean operation as described above and then reseasoned.