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 system for performing atomic layer deposition comprising:
a housing;
a moving bed which passes through the housing, the moving bed including a reaction surface;
a first precursor gas input opening into the housing and configured to provide a first precursor gas and a second precursor gas input opening into the housing and configured to provide a second precursor gas, the first precursor gas input and the second precursor gas input spaced apart by a precursor decay length such that all of the first precursor gas is reacted with the reaction surface prior to reaching the second precursor gas input;
a carrier gas input configured to provide a carrier gas flow having a flow rate of u through the housing, the carrier gas input in communication with the first precursor gas input and the second precursor gas input;
wherein the first precursor gas input is entirely positioned between the carrier gas input and the second precursor gas input and the first precursor gas input and the second precursor gas input are configured to input into the carrier gas flow, respectively, the first precursor gas and the second precursor gas, at the same time; and
wherein the precursor decay length is given by L(ε):
L
(
ɛ
)
=
4
u
d
υ
th
β
(
1
-
c
0
)
log
(
1
-
c
0
(
1
-
ɛ
)
ɛ
)
wherein u is an average flow velocity, c 0 is a final coverage after all precursor is consumed, νth is average thermal velocity, β is bare reaction probability for the atomic layer deposition, d is a vertical gap of the first precursor gas input and the second precursor gas input from the moving bed and ε is tolerance for precursor depletion, all under an assumption of a first order irreversible Langmuir kinetics; and
wherein the system is free of physical separation and flow-induced separation between the first precursor gas input and the second precursor gas input.
2. The system as defined in claim 1 , wherein the moving bed is constructed to be of a prescribed length passing through the housing to ensure complete exhaustion of the precursor gases input to the housing and the precursor gases react with the available reaction sites.
3. The system as defined in claim 1 further including a device coupled to the moving bed for mixing particles comprising the reaction surface.
4. The system as defined in claim 1 further including a control system for controlling at least one of (a) carrier gas flow rate, (b) velocity of motion of the moving bed, and (c) direction of motion of the moving bed relative to the carrier gas and/or the precursor gases.
5. The system as defined in claim 1 , wherein the amounts of the precursor gas are less than available reaction sites of the reaction surface, thereby leading to exhaustion of the precursor gases input into the housing.
6. The system as defined in claim 1 , wherein the system comprises gas inputs consisting of the first precursor gas input, the second precursor gas input, and the carrier gas input.
7. A system for performing atomic layer deposition comprising:
a housing;
a moving bed which passes through the housing of the moving bed including a reaction surface;
gas inputs consisting of a first precursor gas input, a second precursor gas input, and a carrier gas input;
a flow control in communication with the first precursor gas input and the second precursor gas input and configured to control the flow of first precursor gas and second precursor gas; and
a mechanical agitation device coupled to the moving bed;
wherein the first precursor gas input opens into the housing and is configured to provide a first precursor gas and the second precursor gas input opens into the housing and is configured to provide a second precursor gas, the first precursor gas input and the second precursor gas input spaced apart by a precursor decay length such that all of the first precursor gas is reacted with the reaction surface prior to reaching the second precursor gas input;
wherein the carrier gas input is in communication with the first precursor gas input and the second precursor gas input;
wherein the first precursor gas input is positioned entirely between the carrier gas input and the second precursor gas input and the first precursor gas input and the second precursor gas input are configured to input into the carrier gas flow, respectively, the first precursor gas and the second precursor gas, at the same time; and
wherein the precursor decay length is given by L(ε):
L
(
ɛ
)
=
4
u
d
υ
th
β
(
1
-
c
0
)
log
(
1
-
c
0
(
1
-
ɛ
)
ɛ
)
wherein u is an average flow velocity, c 0 is a final coverage after all precursor is consumed, νth is average thermal velocity, β is bare reaction probability for the atomic layer deposition, d is a vertical gap of the first precursor gas input and the second precursor gas input from the moving bed and ε is tolerance for precursor depletion, all under an assumption of a first order irreversible Langmuir kinetics wherein the system is free of physical separation and flow-induced separation between the first precursor gas input and the second precursor gas input.
8. The system as defined in claim 7 , wherein the moving bed is constructed to be of a prescribed length passing through the housing to ensure complete exhaustion of the precursor gases input to the housing and the precursor gases react with the available reaction sites.
9. The system as defined in claim 7 , wherein the amounts of the precursor gas are less than available reaction sites of the reaction surface, thereby leading to exhaustion of the precursor gases input into the housing.