Phosphorous trifluoride co-gas for carbon implants
AssigneeAxcelis Technologies, Inc.
InventorsNeil Colvin, Tseh-Jen Hsieh
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Abstract
Processes and systems for carbon ion implantation include utilizing phosphorous trifluoride (PF3) as a co-gas with carbon oxide gas, and in some embodiments, in combination with the lanthanated tungsten alloy ion source components advantageously results in minimal oxidation of the cathode and cathode shield. Moreover, acceptable levels of carbon deposits on the arc chamber internal components have been observed as well as marked reductions in the halogen cycle, i.e., WFx formation.
Claims12
A process for implanting carbon into a substrate, the process comprising:
- ionizing a carbon oxide gas source and a co-gas comprising phosphorous trifluoride in an ion source chamber to produce carbon ions and phosphorous oxide;
- detecting formation of phosphorous oxides based on analysis of atomic mass unit spectra;
- determining a final ratio between the carbon oxide gas source and the co-gas comparing the phosphorous trifluoride when the phosphorous oxides are no longer detectable;
- and
- implanting the carbon ions into the substrate.
A process for implanting carbon ions into a workpiece, the process comprising:
- supplying a mixture of a carbon oxide gas and a phosphorous trifluoride gas to an ion source, wherein the ion source and an ion implantation system containing the ion source comprises a cathode, a cathode shield, and/or a repeller formed of or coated with lanthanum tungsten;
- ionizing the carbon oxide gas and the phosphorous trifluoride gas with the ion source at a stoichiometry effective to create a feedstream of ionized carbon and a byproduct comprising phosphorous oxides, wherein the stoichiometry is in accordance with reaction scheme III having corresponding atomic mass units shown in parenthesis:
- 19CO+7PF3+4LaW17C++O+20F+2CO+P+PO+2La2O3+3W+WO3+P4O6. III.
- extracting the ionized carbon within the plasma to form an ion beam;
- and
- exposing the workpiece to the ion beam to implant the ionized carbon into the workpiece.
Dependencies are inferred from the claim text.