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 semiconductor processing apparatus comprising:
a process chamber configured to receive a wafer;
an ampoule configured to contain a precursor;
a flowpath spanning between and fluidically connecting the ampoule and the process chamber;
an ampoule valve that is fluidically connected to the ampoule and the flow path, and that controls flow of the precursor from the ampoule into the flowpath;
a process chamber valve that if fluidically connected to the process chamber and the flowpath, and that controls gas flow from the flowpath into the process chamber;
and
a controller comprising control logic for:
causing the ampoule valve to open, before a dose step by an amount of time that is substantially equal to a line charge time, to start a flow of the precursor from the ampoule to the process chamber through the flowpath, wherein the line charge time is the time required for the precursor to flow from the ampoule to the process chamber through the flowpath,
causing the ampoule valve to close to stop the precursor from flowing out of the ampoule,
causing the process chamber valve to open, at the beginning of the dose step, to allow the flow of the precursor to enter the process chamber, and
causing the process chamber valve to close, at the end of the dose step, to stop the flow of the precursor from entering the process chamber.
2. The semiconductor processing apparatus of claim 1 , wherein:
causing the ampoule valve to close further includes causing the ampoule valve to close after opening the ampoule valve by an amount of time that is substantially equal to a desired adsorption time for the dose step,
causing the process chamber valve to open further includes causing the process chamber valve to open after opening the ampoule valve by an amount of time that is substantially equal to the line charge time, and
causing the process chamber valve to close further includes causing the process chamber valve to close after opening the process chamber valve by an amount of time substantially equal to the desired adsorption time.
3. The semiconductor processing apparatus of claim 1 , wherein causing the ampoule valve to open further includes causing the ampoule valve to open before the dose step to cause the precursor to reach the process chamber at the start of the dose step.
4. The controller of claim 1 , wherein the causing the ampoule valve to close further includes causing the ampoule valve to close after an amount of precursor is in the gas line to achieve a desired adsorption onto a wafer.