Use of spectroscopic techniques to monitor and control reactant gas input into a pre-pump reactive gas injection system
View Patent ↗The present invention relates to vacuum processing systems in which process gases are introduced in a process chamber and are exhausted through a vacuum processing system exhaust path. Deposits made by the exhausted gas are reduced or eliminated by introducing a reactive gas upstream of the device affected by deposits. The amount of introduced reactive gas is controlled by measuring gas phase concentrations of exhausted gas components upstream and downstream of the affected device, and, from those measurements, determining whether the components are being consumed in deposits on the affected device.
1. A method for controlling deposits made by at least one component of an exhaust gas on a device in a vacuum processing system exhaust path, the method comprising the steps of:
introducing a flow of a reactant gas into the vacuum processing system exhaust path at a position upstream of the device, the reactant gas inhibiting the deposits made by the at least one component of the exhaust gas;
measuring a quantity of the at least one component of the exhaust gas present at a position upstream of the device;
measuring a quantity of the at least one component of the exhaust gas present at a position downstream of the device;
determining from the upstream and downstream measurements whether at least a predetermined portion of the at least one component of the exhaust gas is consumed in the device; and, if so;
increasing the flow of the reactant gas.
2. The method of claim 1 , further comprising the steps of
determining from the upstream and downstream measurements whether substantially none of the at least one component of the exhaust gas is consumed in the device; and, if so,
determining whether excess reactant gas is flowing through the device; and, if so,
decreasing the flow of reactant gas.
3. The method of claim 1 , wherein the measuring steps comprise measuring the quantity of the at least one component of the exhaust gas using an instrument selected from the group consisting of an infrared spectrometer, a Raman Spectrometer, a mass spectrometer and a laser induced fluorescence spectrometer.
4. The method of claim 1 , wherein the reactant gas is fluorine.
5. The method of claim 1 , wherein the step of introducing a flow of a reactant gas into the vacuum processing system exhaust path further comprises dissociating a precursor gas using a remote plasma source.
6. The method of claim 5 , wherein the reactant gas is fluorine and the precursor gas is NF 3 .
7. The method of claim 1 , wherein the device is selected from a group consisting of a vacuum pump and an abatement device.
8. The method of claim 1 , wherein the at least one component of the exhaust gas is tungsten fluoride.
9. The method of claim 8 , wherein the reactant gas is fluorine.
10. The method of claim 1 , wherein the at least one component of the exhaust gas comprises at least one gas selected from the group consisting of WF 3 , H 2 , NH 3 , B 2 H 6 and SiH 4 .
11. The method of claim 1 , wherein the measuring steps comprise measuring a gas phase concentration of the at least one component.