Dynamic precursor dosing for atomic layer deposition

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.

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.