The invention relates to an apparatus and process for the vaporization of liquid precursors and deposition of a film on a suitable substrate. In one aspect, an apparatus and process for the control of a gas flowed through a gas feedthrough in a substrate processing chamber and system is provided. In another aspect, a deposition chamber is provided for depositing BST and other materials which require vaporization, especially low volatility precursors which are transported as a liquid to a vaporizer to be converted to vapor phase and which must be transported at elevated temperatures to prevent unwanted condensation on chamber components. The chamber comprises a series of heated temperature controlled internal liners, such as a heated gas feedthrough.