Apparatus and methods for roll-to-roll (R2R) plasma enhanced/activated atomic layer deposition (PEALD/PAALD)
Techniques are disclosed for roll-to-roll (R2R) atomic layer deposition (ALD). R2R ALD is accomplished by arranging precursor nozzles in A/B pairs while a flexible web substrate moves underneath the A/B pairs at a uniform speed. Nozzles A of the A/B pairs continuously flow a precursor A into the process volume of the R2R ALD chamber. The plasma enhanced/activated ALD (PEALD/PAALD) embodiments utilize electron cyclotron resonance or rotation (ECR)-enhanced hollow cathode plasma sources (HCPS) where nozzles B flow activated neutrals of precursor B into the process volume. As the flexible web moves in an R2R motion, nucleates from precursor A deposited on the surface of the substrate, and neutrals of precursor B undergo a self-limiting reaction to deposit a single atomically sized ALD film/layer. In this manner, multiple ALD layers may be deposited by each successive A/B pair in a single pass of the web. There is also a heat source underneath the web to further facilitate the ALD reaction, or to support thermal ALD embodiments.
1. A method comprising the steps of:
(a) continuously flowing a precursor A and activated neutrals of a precursor B from a first plurality of nozzles and a second plurality of nozzles respectively into a roll-to-roll (R2R) atomic layer deposition (ALD) chamber, wherein said first plurality of nozzles and said second plurality of nozzles are arranged linearly in one or more A/B pairs in a direction perpendicular to a roll-to-roll motion of a flexible web occurring at a constant speed underneath said A/B pairs, wherein said second plurality of nozzles comprise a respective plurality of electron cyclotron resonance (ECR)-enhanced hollow cathode plasma sources (HCPSes) for producing a plasma of said precursor B, and wherein said respective plurality of ECR-enhanced HCPSes comprise a corresponding plurality of cylindrical and aligned magnets around a corresponding plurality of hollow cathodes;
(b) placing a ceramic plug containing a pinhole underneath each of said second plurality of nozzles to allow activated neutrals of said precursor B to flow into said R2R ALD chamber while preventing said plasma from flowing into said R2R ALD chamber and from coming in contact with said flexible web; and
(c) depositing one or more uniform atomically sized ALD layers on a surface of said flexible web as a result of a self-limiting reaction on said surface between nucleates from said precursor A and said activated neutrals of precursor B, and wherein said self-limiting reaction consists only of an ALD reaction, and without requiring intervening purge and exhaust operations, and without requiring complete consumption of precursor A, and wherein:
(d) a distance between the lower ends of said first plurality and said second plurality of nozzles and said flexible web is substantially in the range of 1 inch to 2 inches;
(e) a spacing between each of said first plurality of nozzles is substantially in the range of 0.5 inch to 1 inch;
(f) a spacing between each of said second plurality of nozzles is substantially in the range of 0.5 inch to 1 inch; and
(g) a spacing between said first plurality of nozzles and said second plurality of nozzles is greater than 2 inches.
2. The method of claim 1 depositing said one or more uniform atomically sized ALD layers across an entire width of said flexible web.
3. The method of claim 1 utilizing a heating element to heat said flexible web for further facilitating said self-limiting reaction.
4. The method of claim 1 providing a temperature of said flexible web to be substantially in the range of 20° C. to 300° C.
5. The method of claim 1 utilizing one A/B pair amongst said one or more A/B pairs to deposit one of said one or more uniform atomically sized ALD layers in a single pass of said flexible web.
6. The method of claim 1 further providing an evacuation port in said R2R ALD chamber underneath a roll which said flexible web is wound onto, said evacuation port used for pumping out unreacted quantities of said precursor A and said precursor B.
7. The method of claim 6 preventing said precursor A and said activated neutrals of said precursor B from sticking to said surface once said surface is saturated by said self-limiting reaction.
8. The method of claim 1 providing a diameter of said pinhole in said ceramic plug to be substantially in the range of 20 mills to 40 mills.
9. The method of claim 1 , providing an inside pressure of said R2R ALD chamber to be substantially in the range of 0.1 Torr to 0.5 Torr.
10. The method of claim 1 providing said one more uniform atomically sized ALD layers to include one or both of an oxide layer and a nitride layer.