Deposition method and apparatus
A method of depositing a material on a substrate comprises placing a substrate into a process space in fluidic communication with a Gaede pump stage (GPS). A precursor gas is then injected into the process space while injecting a draw gas at a draw gas flow rate into the GPS such that the injected precursor gas achieves a precursor pressure and a precursor gas flow rate in the process space. Subsequently, substantially all of the precursor gas remaining in the process space is swept from the process space by injecting a sweep gas into the process space such that the injected sweep gas achieves a sweep pressure and sweep gas flow rate in the process space. The precursor pressure is higher than the sweep pressure, and the precursor gas flow rate is lower than the sweep gas flow rate.
1. A method for depositing a material on a substrate, the method comprising the steps of:
placing the substrate into a process space in fluidic communication with a Gaede pump stage (GPS);
injecting a precursor gas into the process space while injecting a draw gas at a draw gas flow rate directly into the GPS such that the injected precursor gas achieves a precursor pressure and a precursor gas flow rate in the process space; and
sweeping substantially all of the precursor gas remaining in the process space from the process space by injecting a sweep gas into the process space such that the injected sweep gas achieves a sweep pressure and sweep gas flow rate in the process space;
wherein the precursor gas flow rate is lower than the sweep gas flow rate.
2. The method of claim 1 , wherein the precursor pressure is higher than the sweep pressure.
3. The method of claim 1 , further comprising the step of injecting a second precursor gas into the process space while injecting a second draw gas at a second draw gas flow rate directly into the GPS such that the injected second precursor gas achieves a second precursor pressure and a second precursor gas flow rate in the process space, the second precursor gas flow rate being lower than the sweep gas flow rate.
4. The method of claim 3 , wherein the second precursor pressure is higher than the sweep pressure.
5. The method of claim 3 , wherein the second draw gas has substantially the same composition as the draw gas.
6. The method of claim 3 , wherein the second draw gas flow rate is substantially the same as the draw gas flow rate.
7. The method of claim 3 , wherein the second precursor pressure differs from the precursor pressure.
8. The method of claim 1 , wherein depositing the material comprises atomic layer deposition.
9. The method of claim 1 , wherein the draw gas flow rate is higher than the sweep gas flow rate.
10. The method of claim 1 , wherein the GPS displays a lower compression ratio while the precursor gas is injected into the process space than it does while the sweep gas is injected into the process space.
11. The method of claim 1 , wherein the GPS displays a compression ratio between about 10 and about 50 while the sweep gas is injected into the process space.
12. The method of claim 1 , wherein the sweep gas injected into the process space displays a residence time less than about 25 milliseconds.
13. The method of claim 1 , wherein the GPS is operative to switch between the precursor pressure and the sweep pressure in less than about five milliseconds.
14. The method of claim 1 , further comprising the step of passing the precursor gas swept from process space by the sweep gas through an abatement space, the abatement space comprising an abatement surface on which the precursor gas may be converted to a film in the presence of an abatement gas.
15. The method of claim 14 , further comprising the step of modulating a pressure in the abatement space from a first abatement pressure to a second abatement pressure while injecting sweep gas into the process space, the first abatement pressure being higher than the second abatement pressure.