Abstract: A chemical vapor deposition apparatus for depositing films or coatings on semiconductor substrates. Substrates are supported within an air tight reactor and heated to a predetermined reaction temperature. A manifold disposed within the reactor, and having a plurality of openings therein, receives one or more reactive vapors and evenly distributes the vapors through the openings in the vicinity of the substrates, such that the vapors react at the substrate surfaces and a film or coating is deposited thereon. One or more cooling tubes substantially envelope the manifold, thereby maintaining the manifold at a temperature less than at least the reaction temperature such that the vapors do not prematurely react within the manifold. Hence, films and coatings are prevented from forming within the manifold, and sufficient unreacted vapors are supplied to the substrate to effect a satisfactory coating or film thereon.