Procedure for etch rate consistency
Methods of conditioning interior processing chamber walls of an etch chamber are described. A fluorine-containing precursor may be remotely or locally excited in a plasma to treat the interior chamber walls periodically on a preventative maintenance schedule. The treated walls promote an even etch rate when used to perform gas-phase etching of silicon regions following conditioning. Alternatively, a hydrogen-containing precursor may be remotely or locally excited in a plasma to treat the interior chamber walls in embodiments. Regions of exposed silicon may then be etched with more reproducible etch rates from wafer-to-wafer. The silicon etch may be performed using plasma effluents formed from a remotely excited fluorine-containing precursor.
1. A method of conditioning a substrate processing region, the method comprising:
exciting a conditioning fluorine-containing precursor in a conditioning plasma to produce conditioning plasma effluents;
exposing interior processing chamber walls to the conditioning plasma effluents, wherein the interior processing chamber walls border a substrate processing region and exposing interior processing chamber walls to the conditioning plasma effluents results in a chemical termination on the interior processing chamber walls;
(i) transferring a substrate into the substrate processing region following the operation of exposing the interior processing chamber walls to the conditioning plasma effluents, wherein the substrate comprises exposed silicon region;
(ii) flowing an etching fluorine-containing precursor into a remote plasma region fluidly coupled to the substrate processing region while forming a remote plasma in the remote plasma region to produce etching plasma effluents; and
(iii) etching the exposed silicon region by flowing the etching plasma effluents into the substrate processing region through through-holes in a showerhead, wherein the showerhead is disposed between the remote plasma region and the substrate processing region
wherein repeated substrate processing does not cause the chemical termination on the interior processing chamber walls to evolve over time.
2. The method of claim 1 wherein the conditioning fluorine-containing precursor comprises one or more of atomic fluorine, diatomic fluorine, boron trifluoride, chlorine trifluoride, nitrogen trifluoride, perfluorinated hydrocarbons, sulfur hexafluoride and xenon difluoride.
3. The method of claim 1 wherein the etching fluorine-containing precursor comprises one or more of atomic fluorine, diatomic fluorine, boron trifluoride, chlorine trifluoride, nitrogen trifluoride, hydrogen fluoride, fluorinated hydrocarbons, sulfur hexafluoride and xenon difluoride.
4. The method of claim 1 wherein the substrate processing region is essentially devoid of hydrogen during the operation of exposing the interior processing chamber walls to the conditioning plasma effluents.
5. The method of claim 1 wherein the conditioning plasma is a local conditioning plasma inside the substrate processing region.
6. The method of claim 1 wherein the conditioning plasma is a remote conditioning plasma outside the substrate processing region and the conditioning plasma effluents are flowed from the remote plasma into the substrate processing region.
7. The method of claim 1 wherein the repeated substrate processing exhibits a stable silicon etch rate over 900 substrates.