fig1 is a generalized step diagram of a process for practicing the present invention . two reactive gases are used , a first molecular precursor and a second molecular precursor . gases are supplied from a gas source and can be delivered to the substrate , for example , via a distribution manifold . metering and valving apparatus for providing gaseous materials to the distribution manifold can be used . as shown in step 1 , a continuous supply of gaseous materials for the system is provided for depositing a thin film of material on a substrate . the steps in sequence 15 are sequentially applied . in step 2 , with respect to a given area of the substrate ( referred to as the channel area ), a first molecular precursor or reactive gaseous material is directed to flow in a first channel transversely over the channel area of the substrate and reacts therewith . in step 3 relative movement of the substrate and the multi - channel flows in the system occurs , which sets the stage for step 4 , in which second channel ( purge ) flow with inert gas occurs over the given channel area . then , in step 5 , relative movement of the substrate and the multi - channel flows sets the stage for step 6 , in which the given channel area is subjected to atomic layer deposition in which a second molecular precursor now transversely flows ( substantially parallel to the surface of the substrate ) over the given channel area of the substrate and reacts with the previous layer on the substrate to produce ( theoretically ) a monolayer of a desired material . often in such processes , a first molecular precursor is a metal - containing compound in gas form ( for example , a metallic compound such as titanium tetrachloride ) and the material deposited is a metal - containing compound . in such an embodiment , the second molecular precursor can be , for example , a non - metallic oxidizing compound or hydrolyzing compound , e . g . water . in step 7 , relative movement of the substrate and the multi - channel flows then sets the stage for step 8 in which again an inert gas is used , this time to sweep excess second molecular precursor from the given channel area from the previous step 6 . in step 9 , relative movement of the substrate and the multi - channels occurs again , which sets the stage for a repeat sequence , back to step 2 . the cycle is repeated as many times as is necessary to establish a desired film or layer . the steps may be repeated with respect to a given channel area of the substrate , corresponding to the area covered by a flow channel . meanwhile the various channels are being supplied with the necessary gaseous materials in step 1 . simultaneous with the sequence of box 15 in fig1 , other adjacent channel areas are being 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 of the thin film can be increased by repeating the process cycle ( steps 2 - 9 ). because the film can be deposited one monolayer at a time it tends to be conformal and have uniform thickness . referring now to fig2 , there is shown a cross - sectional side view of one embodiment of a distribution manifold 10 that can be used in the present process for atomic layer deposition onto a substrate 20 . distribution manifold 10 has a gas inlet port 14 for accepting a first gaseous material , a gas inlet port 16 for accepting a second gaseous material , and a gas inlet port 18 for accepting a third gaseous material . these gases are emitted at an output face 36 via output channels 12 , having a structural arrangement described subsequently . the arrows in fig2 refer to the diffusive transport of the gaseous material , and not the flow , received from an output channel . the flow is substantially directed out of the page of the figure . gas inlet ports 14 and 16 are adapted to accept first and second gases that react sequentially on the substrate surface to effect ald deposition , and gas inlet port 18 receives a purge gas that is inert with respect to the first and second gases . distribution manifold 10 is spaced a distance d from substrate 20 , provided on a substrate support . reciprocating motion can be provided between substrate 20 and distribution manifold 10 , either by movement of substrate 20 , by movement of distribution manifold 10 , or by movement of both substrate 20 and distribution manifold 10 . in the particular embodiment shown in fig2 , substrate 20 is moved across output face 36 in reciprocating fashion , as indicated by the arrow r and by phantom outlines to the right and left of substrate 20 in fig2 . it should be noted that reciprocating motion is not always required for thin - film deposition using distribution manifold 10 . other types of relative motion between substrate 20 and distribution manifold 10 could also be provided , such as movement of either substrate 20 or distribution manifold 10 in one or more directions . the cross - sectional view of fig3 shows gas flows emitted over a portion of front face 36 of distribution manifold 10 . in this particular arrangement , each output channel 12 is in gaseous flow communication with one of gas inlet ports 14 , 16 or 18 seen in fig2 . each output channel 12 delivers typically a first reactant gaseous material o , or a second reactant gaseous material m , or a third inert gaseous material i . fig3 shows a relatively basic or simple arrangement of gases . it is possible that a plurality of non - metal deposition precursors ( like material o ) or a plurality of metal - containing precursor materials ( like material m ) may be delivered sequentially at various ports in a thin - film single deposition . alternately , a mixture of reactant gases , for example , a mixture of metal precursor materials or a mixture of metal and non - metal precursors may be applied at a single output channel when making complex thin film materials , for example , having alternate layers of metals or having lesser amounts of dopants admixed in a metal oxide material . the critical requirement is that an inert stream labeled i should separate any reactant channels in which the gases are likely to react with each other . first and second reactant gaseous materials o and m react with each other to effect ald deposition , but neither reactant gaseous material o nor m reacts with inert gaseous material i . the cross - sectional views of fig4 a and 4b show , in simplified schematic form , the ald coating operation performed as substrate 20 passes along output face 36 of distribution manifold 10 when delivering reactant gaseous materials o and m . in fig4 a , the surface of substrate 20 first receives an oxidizing material from output channels 12 designated as delivering first reactant gaseous material o . the surface of the substrate now contains a partially reacted form of material o , which is susceptible to reaction with material m . then , as substrate 20 passes into the path of the metal compound of second reactant gaseous material m , the reaction with m takes place , forming a metallic oxide or some other thin film material that can be formed from two reactant gaseous materials . as fig4 a and 4b show , inert gaseous material i is provided in every alternate output channel 12 , between the flows of first and second reactant gaseous materials o and m . sequential output channels 12 are adjacent , that is , share a common boundary , formed by partitions 22 in the embodiments shown . here , output channels 12 are defined and separated from each other by partitions 22 that extend perpendicular to the surface of substrate 20 . notably , there are no vacuum channels interspersed between the output channels 12 , that is , no vacuum channels on either side of a channel delivering gaseous materials to draw the gaseous materials around the partitions . this advantageous , compact arrangement is possible because of the innovative gas flow that is used . unlike gas delivery arrays of earlier processes that apply substantially vertical ( that is , perpendicular ) gas flows against the substrate and should then draw off spent gases in the opposite vertical direction , distribution manifold 10 directs a gas flow ( preferably substantially laminar in one embodiment ) along the surface for each reactant and inert gas and handles spent gases and reaction by - products in a different manner . the gas flow used in the present invention is directed along and generally parallel to the plane of the substrate surface . in other words , the flow of gases is substantially transverse to the plane of a substrate rather than perpendicular to the substrate being treated . the above described method and apparatus are one example of a vapour deposition process that can by used in the present invention . the invention works equally well using chemical vapour depositions . in the example ald / cvd coating was carried out using apparatus similar to that described above . either titanium dioxide or alumina was coated . for titanium dioxide , titanium tetrachloride was in one bubbler and water in the other . for alumina , a 1m solution of trimethylaluminium in heptane was in one bubbler and water in the other . for both oxides , the flow rate of the carrier gas through the bubblers was 50 ml / min . the flow rate of diluting carrier gas was 300 ml / min for the water reactant and 150 ml / min for the titanium tetrachloride or trimethylaluminium . the flow rate of the inert separator gas was 21 / min . nitrogen was used for the carrier gas in all instances . a calibration was run to determine the thickness versus number of substrate oscillations for both oxides . a small piece of tape , acting as a mask , was stuck to a 63 × 63 × 1 mm piece of borosilicate glass which was coated with gh17r ( nippon gohsei ) 10 % polyvinylalcohol , pva , using a gravure roller using a 150 micron bar . the thickness of the pva layer not masked was estimated to be about 15 microns . the tape was removed to leave a hole in the pva coating creating a simple pattern . the entire substrate was coated with a layer of titanium dioxide about 100 nm thick . the edge of the pva coating was found and peeled off , removing the titanium dioxide coating which was on top of the pva layer . the thicknesses of the titanium dioxide remaining on the glass were determined by ellipsometer . it was found that there was no titanium dioxide where there had previously been pva and a layer thickness of 101 nm where there had been none . it will be understood that the material used for the first layer need not be pva , as in the above example . any suitable film forming polymer with low adhesion to the substrate may be used . similarly the second material is not limited to those used in the example described above . the second material may be any metal , metal oxide , metal nitride , metal sulphide , metal oxysulphide or metal oxynitride . the invention has been described in detail with reference to preferred embodiments thereof . it will be understood by those skilled in the art that variations and modifications can be effected within the scope of the invention .