In-situ conditioning for vacuum processing of polymer substrates
View Patent ↗An etching chamber is equipped with an actively-cooled element preferentially adsorbs volatile compounds that are evolved from a polymeric layer of a wafer during etching, which compounds will act as contaminants if re-deposited on the wafer, for example on exposed metal contact portions where they may interfere with subsequent deposition of metal contact layers. In desirable embodiments, a getter sublimation pump is also provided in the etching chamber as a source of getter material. Methods of etching in such a chamber are also disclosed.
1. A method of sputtering comprising:
a) placing a wafer from which it is desired to remove metal oxide deposits on a support surface in a sputter etching chamber comprising an inlet for the introduction of ionizable gas, wherein the support surface located in said chamber is adapted to support the wafer to be etched in the chamber, and an actively-cooled element is located in the chamber adjacent said support surface;
b) chilling said actively-cooled element to a temperature in the range of −50 to +10° C.; and
c) ionizing an ionizable gas in said chamber to produce a plasma therefrom, said plasma etching said wafer to remove metal oxide deposits;
wherein volatile compounds evolved from said wafer as a result of said etching are preferentially adsorbed onto said actively-cooled element as compared to other surfaces in said chamber,
wherein said actively-cooled element comprises a dark space shield located at a base of said sputter etching chamber,
wherein the etching chamber further comprises a getter sublimation pump located in said chamber, and wherein the etching chamber further comprises a layer of getter material deposited on a surface of said actively-cooled element.
2. The method of claim 1 , said temperature being in the range of −20 to +10° C.
3. The method of claim 1 , said temperature being in the range of −20 to 0° C.
4. The method of claim 1 , said actively-cooled element is located adjacent the support surface of a pedestal at a base of said chamber.
5. The method of claim 1 , wherein the getter sublimation pump comprises a getter material, and said method further comprising:
d) sputtering said getter sublimation pump to evaporate the getter material therefrom and deposit the same on said actively-cooled element.
6. The method of claim 5 , comprising carrying out said steps (a) through (c) to remove metal oxide deposits from one wafer, thereafter removing said one wafer from said etching chamber, thereafter carrying out step (d) with no wafer in said etching chamber, and thereafter inserting a further wafer in said etching chamber and carrying out steps (a) through (c) on said further wafer.
7. The method of claim 5 , comprising repeating said steps (a) through (c) to remove metal oxide deposits from a first plurality of successive wafers, thereafter carrying out step (d) with no wafer in said etching chamber, and thereafter again repeating said steps (a) through (c) to remove metal oxide deposits from a further plurality of successive wafers.
8. The method of claim 1 , wherein the getter sublimation pump comprises a resistively-heated wire comprising the getter material, and said method further comprising energizing said wire to evaporate getter material therefrom during step (c).
9. The method of claim 8 , said wire being energized to evaporate getter material therefrom during step (c) on-demand based on a time-dependent profile for evolution of volatile compounds from said wafer during etching.
10. The method of claim 1 , comprising carrying out said steps (a) through (c) to remove metal oxide deposits from one wafer, thereafter removing said one wafer from said etching chamber, thereafter inserting a getter substrate that comprises or is coated with a getter material, thereafter plasma etching said getter substrate to remove getter material therefrom to be deposited on interior surfaces in said etching chamber, and thereafter inserting a further wafer in said etching chamber and carrying out steps (a) through (c) on said further wafer.
11. The method of claim 1 , comprising repeating said steps (a) through (c) to remove metal oxide deposits from a first plurality of successive wafers, thereafter inserting in said etching chamber a getter substrate that comprises or is coated with a getter material, thereafter plasma etching said getter substrate to remove getter material therefrom to be deposited on interior surfaces in said etching chamber, thereafter removing said getter substrate from said etching chamber, and thereafter again repeating said steps (a) through (c) to remove metal oxide deposits from a second plurality of successive wafers.
12. The method of claim 1 , said support surface having an exposed perimeter area that extends radially outward from said wafer resting thereon during step (c), said perimeter area comprising getter material, wherein plasma sputtering during step (c) removes getter material from said perimeter area of said support surface, which is deposited onto other surfaces within said chamber.
13. A method of sputtering comprising:
a) placing a wafer from which it is desired to remove metal oxide deposits on a support surface in a sputter etching chamber comprising an inlet for the introduction of ionizable gas, wherein the support surface located in said chamber is adapted to support a wafer to be etched in the chamber, and an actively-cooled element is located in the chamber adjacent said support surface;
b) chilling said actively-cooled element to a temperature in the range of −50 to +10° C.; and
c) ionizing an ionizable gas in said chamber to produce a plasma therefrom, said plasma etching said wafer to remove metal oxide deposits;
wherein volatile compounds evolved from said wafer as a result of said etching are preferentially adsorbed onto said actively-cooled element as compared to other surfaces in said chamber,
wherein said actively-cooled element comprises a dark space shield located at a base of said sputter etching chamber,
wherein the sputter etching chamber further comprises a pedestal disposed at least partially within said chamber, said support surface being a surface of said pedestal, said getter sublimation pump comprising at least a portion of said pedestal made from or coated with a getter material.
14. The method of sputtering according to claim 1 , wherein the dark space shield comprises a portion of a pump channel.