processed simultaneously which results in multiple channel flows in parallel as indicated in overall step 11 the primary purpose of the second molecular precursor is to condition the substrate surface back toward reactivity with the first molecular precursor the second molecular precursor also provides material as a molecular gas to combine with one or more metal compounds at the surface forming compounds such as an oxide nitride sulfide etc with the freshly deposited metal containing precursor the continuous ald purge does not need to use a vacuum purge to remove a molecular precursor after applying it to the substrate assuming that two reactant gases ax and by are used when the reaction gas ax flow is supplied and flowed over a given substrate area atoms of the reaction gas ax are chemically adsorbed on a substrate resulting in a layer of a and a surface of ligand x associative chemisorptions step 2 then the remaining reaction gas ax is purged with an inert gas step 4 then the flow of reaction gas by and a chemical reaction between ax surface and by gas occurs resulting in a molecular layer of ab on the substrate dissociative chemisorptions step 6 the remaining gas by and by products of the reaction are purged step 8 the thickness.