Dynamic precursor dosing for atomic layer deposition
Methods and apparatuses for controlling precursor flow in a semiconductor processing tool are disclosed. A method may include flowing gas through a gas line, opening an ampoule valve(s), before a dose step, to start a flow of precursor from the ampoule to a process chamber through the gas line, closing the ampoule valve(s) to stop the precursor from flowing out of the ampoule, opening a process chamber valve, at the beginning of the dose step, to allow the flow of precursor to enter the process chamber, and closing the process chamber valve, at the end of the dose step, to stop the flow of precursor from entering the process chamber. A controller may include at least one memory and at least one processor and the at least one memory may store instructions for controlling the at least one processor to control precursor flow in a semiconductor processing tool.
1. A method for controlling precursor flow in a semiconductor processing tool, the method comprising:
(a) flowing gas through a gas line;
(b) opening one or more valves of an ampoule, before a dose step by an amount of time that is substantially equal to a line charge time, to start a flow of precursor from the ampoule to a process chamber through the gas line, wherein the line charge time is the time required for precursor to flow from the ampoule to the process chamber;
(c) closing the one or more valves of an ampoule to stop the precursor from flowing out of the ampoule;
(d) opening a process chamber valve, at the beginning of the dose step, to allow the flow of precursor to enter the process chamber; and
(e) closing the process chamber valve, at the end of the dose step, to stop the flow of precursor from entering the process chamber.
2. The method of claim 1 , wherein closing the one or more valves of an ampoule in (c) occurs before the closing of the process chamber valve in (e) by an amount of time that is substantially equal to a line charge time, wherein the line charge time is the time required for precursor to flow from the ampoule to the process chamber.
3. The method of claim 1 , wherein opening a process chamber valve in (d) occurs after opening the one or more valves of the ampoule in (b) by an amount of time that is substantially equal to a line charge time, wherein the line charge time is the time required for precursor to flow from the ampoule to the process chamber.
4. The method of claim 1 , wherein closing the process chamber valve in (e) occurs after closing the one or more valves of ampoule in (c) by an amount of time that is substantially equal to a line charge time, wherein the line charge time is the time required for precursor to flow from the ampoule to the process chamber.
5. The method of claim 1 , wherein closing the one or more valves of the ampoule in (c) occurs after opening the flow valves of the ampoule in (b) by an amount of time that is substantially equal to a desired adsorption time for the dose step.
6. The method of claim 1 , wherein closing the process chamber valve in (e) occurs after opening the process chamber valve in (d) by an amount of time substantially equal to a desired adsorption time for the dose step.
7. The method of claim 1 , wherein:
opening one or more valves of an ampoule in (b) occurs before the start of the dose step by an amount of time that is substantially equal to a line charge time, wherein the line charge time is the time required for precursor to flow from the ampoule to the process chamber;
closing the one or more valves of the ampoule in (c) occurs after opening the one or more valves of the ampoule in (b) by an amount of time that is substantially equal to a desired adsorption time for the dose step;
opening a process chamber valve in (d) occurs after opening the one or more valves of the ampoule in (b) by an amount of time that is substantially equal to the line charge time; and
closing the process chamber valve in (e) occurs after opening the process chamber valve in (d) by an amount of time substantially equal to the desired adsorption time.
8. The method of claim 7 , wherein the desired adsorption time is selected from the group consisting of: a time less than the line charge time, a time greater than the line charge time, and a time equal to the line charge time.
9. The method of claim 1 , wherein the one or more valves of the ampoule are opened before the dose step to cause the precursor to reach the process chamber at the start of the dose step.
10. The method of claim 1 , wherein the one or more valves of the ampoule are opened before the dose step to cause the precursor to at least partially fill the gas line at the start of the dose step.
11. The method of claim 1 , wherein the one or more valves of the ampoule are closed before the end of the dose step to cause substantially no precursor to remain in the gas line at the end of the dose step.
12. The method of claim 1 , wherein the one or more valves of the ampoule are closed after an amount of precursor has flowed into the gas line to achieve a desired adsorption onto a wafer.
13. The method of claim 1 , wherein the valve of the process chamber is closed after a desired adsorption onto a wafer has occurred.
14. The method of claim 1 , wherein the valve of the process chamber is closed when substantially no precursor remains in the gas line.
15. The method of claim 1 , further comprising:
determining a line charge time, wherein the line charge time is the time required for precursor to flow from the ampoule to the process chamber.
16. A method for controlling precursor flow in a semiconductor processing tool, the method comprising:
(a) flowing gas through a gas line;
(b) opening one or more valves of an ampoule, before a dose step, to start a flow of precursor from the ampoule to a process chamber through the gas line;
(c) closing the one or more valves of an ampoule to stop the precursor from flowing out of the ampoule;
(d) opening a process chamber valve, at the beginning of the dose step and after opening the one or more valves of the ampoule in (b) by an amount of time that is substantially equal to a line charge time, to allow the flow of precursor to enter the process chamber, wherein the line charge time is the time required for precursor to flow from the ampoule to the process chamber; and
(e) closing the process chamber valve, at the end of the dose step, to stop the flow of precursor from entering the process chamber.
17. A method for controlling precursor flow in a semiconductor processing tool, the method comprising:
(a) flowing gas through a gas line;
(b) opening one or more valves of an ampoule, before a dose step by an amount of time that is substantially equal to a line charge time, to start a flow of precursor from the ampoule to a process chamber through the gas line, wherein the line charge time is the time required for precursor to flow from the ampoule to the process chamber;
(c) closing the one or more valves of an ampoule, after opening the one or more valves of the ampoule in (b) by an amount of time that is substantially equal to a desired adsorption time for the dose step, to stop the precursor from flowing out of the ampoule;
(d) opening a process chamber valve, at the beginning of the dose step and after opening the one or more valves of the ampoule in (b) by an amount of time that is substantially equal to the line charge time; and
(e) closing the process chamber valve, at the end of the dose step and after opening the process chamber valve in (d) by an amount of time substantially equal to the desired adsorption time, to stop the flow of precursor from entering the process chamber.