Method and system for continuous atomic layer deposition
A system and method for continuous atomic layer deposition. The system and method includes a housing, a moving bed which passes through the housing, a plurality of precursor gases and associated input ports and the amount of precursor gases, position of the input ports, and relative velocity of the moving bed and carrier gases enabling exhaustion of the precursor gases at available reaction sites.
1. A method for atomic layer deposition, comprising the steps of,
providing a housing;
providing a moving bed which passes through the housing of the moving bed including a reaction surface;
providing a first precursor gas at a first precursor gas input;
simultaneously providing a second precursor gas at a second precursor gas input spaced apart from the first precursor gas input a distance L; and
controlling the speed of the moving bed and amounts of the first precursor gas released into the housing, the amounts of the first precursor gas being less than available reaction sites of the reaction surface, thereby leading to consumption of the first precursor gases prior to the first precursor gas reaching the second precursor gas input such that the first precursor gas and the second precursor gas are not intermixed.
2. The method as defined in claim 1 wherein the housing further includes an associated plurality of precursor gas input ports positioned to enable the plurality of precursor gases to react with the available reaction sites, thereby consuming the precursor gases input into the housing.
3. The method as defined in claim 1 wherein the moving bed is constructed to be of a prescribed length passing through the housing to insure complete consumption of the precursor gases input to the housing and which react with the available reaction sites.
4. The method as defined in claim 1 further including the step of providing a carrier gas.
5. The method as defined in claim 4 wherein at least one of flow velocity of the carrier gas and velocity of the moving bed is controlled to insure consumption of the precursor gases.
6. The method as defined in claim 1 further including a device coupled to the moving bed for mixing particles comprising the reaction surface.
7. The method as defined in claim 6 wherein relative direction of flow of the carrier gas and the moving bed are controlled.
8. The method as defined in claim 2 wherein spacing of the input ports is adjustable, thereby optimizing reaction of the precursor gases with the available reaction sites.
9. The method as defined in claim 1 wherein multiple processing cycles are included by passing the moving bed a plurality of times through the housing, thereby obtaining about 99% coverage of the available reaction sites on the reaction surface.
10. The method as defined in claim 1 further including the step of selecting reactivity of the precursor gases to control kinetics of the atomic layer deposition on the available reaction sites.
11. The method as defined in claim 1 wherein the housing is disposed in ambient atmosphere and is not isolated from the ambient atmosphere.
12. The method as defined in claim 1 wherein the atomic layer deposition process is continuous.
13. The method as defined in claim 1 further including the steps selected from the group of atomic layer deposition on (a) a catalytic substrate to form a catalyst, (b) a substrate to form a photovoltaic material, (c) a substrate to form a transparent electronic material, (d) a substrate to form a barrier coating for organic photovoltaic, (e) a substrate to form organic light emitting diodes and (f) a substrate to form a transparent conducting oxide material.
14. The method of claim 1 where the speed of the moving bed, v, the flow velocity of the gas in the housing, u, and the ratio of first precursor gas released into the housing to the total number of reactive sites, γ, are selected such that γu/v<1.