Inhibiting excess precursor transport between separate precursor zones in an atomic layer deposition system

A method of depositing a thin film onto a substrate, comprising:

• introducing a first precursor gas into a first precursor zone;
• introducing a second precursor gas into a second precursor zone spaced apart from the first precursor zone, the second precursor gas different from the first precursor gas;
• introducing an inert gas into an isolation zone interposed between the first and second precursor zones;
• imparting relative movement between the substrate and the precursor zones so that a surface of the substrate is sequentially exposed to the first precursor gas, the inert gas, the second precursor gas, and the inert gas, wherein the exposure of the surface to the first precursor gas leaves a chemisorbed portion of the first precursor gas on the surface and an excess non-chemisorbed portion of the first precursor gas on the surface;
• and
• while the surface of the substrate is exposed to the inert gas, actively removing the excess non-chemisorbed first precursor from the surface to inhibit the excess non-chemisorbed first precursor from entering the second precursor zone while leaving the chemisorbed first precursor on the surface,
• whereby, when the substrate is exposed to the second precursor gas, the second precursor gas reacts with the chemisorbed first precursor at the surface to deposit a thin film thereon.