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An integrated sputtering method and reactor for copper or aluminum seed layers in which a plasma sputter reactor initially deposits a thin conformal layer onto a substrate including a high-aspect ratio hole subject to the formation of overhangs. After the seed deposition, the same sputter reactor is

An integrated sputtering method and reactor for copper or aluminum seed layers in which a plasma sputter reactor initially deposits a thin conformal layer onto a substrate including a high-aspect ratio hole subject to the formation of overhangs. After the seed deposition, the same sputter reactor is used to sputter etch the substrate with energetic light ions, especially helium, having an energy sufficiently low that it selectively etches the metallization to the heavier underlying barrier layer, for example, copper over tantalum or aluminum over titanium. An RF inductive coil generates the plasma during the sputtering etching while the target power is turned off. A final copper flash step deposits copper over the bare barrier field region before copper is electrochemically plated to fill the hole. The invention also includes a simultaneous sputter deposition and sputter etch, and an energetic ion processing of the copper seed sidewall.

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The invention claimed is: 1. A method of forming in a substrate a metallic layer principally comprising a metallization metal having a first atomic mass overlying a barrier layer comprising a barrier metal having a second atomic mass greater than said first atomic mass, said metallic and barrier la

The invention claimed is: 1. A method of forming in a substrate a metallic layer principally comprising a metallization metal having a first atomic mass overlying a barrier layer comprising a barrier metal having a second atomic mass greater than said first atomic mass, said metallic and barrier layers formed over at least sidewalls of a hole, said method comprising the steps of: a first step of sputter depositing said metallic layer in a sputter reactor including a target having a target surface area comprising said metallization metal from a plasma that is at least excited with argon as a first sputter gas; and a second step of sputter etching said metallic layer with a second sputter gas having a third atomic mass less than said first atomic mass. 2. The method of claim 1, wherein substantially more argon than helium is supplied into said sputter reactor in said first step and substantially more helium than argon is supplied into said sputter reactor in said second step. 3. The method of claim 1, wherein substantially more helium is supplied into said sputter reactor in said second step than in said first step. 4. The method of claim 1, wherein an amount of power applied during the second step of sputter etching step is substantially reduced from that applied during the first step of sputter depositing. 5. The method of claim 1, wherein said sputter etching step is performed in said sputter reactor. 6. The method of claim 5, wherein said sputter etching step includes applying RF power to a coil in said sputter reactor and applying RF biasing power to a pedestal electrode supporting said substrate. 7. The method of claim 1, further comprising a subsequent third step of sputter depositing another metallization layer in the sputter reactor including the target. 8. The method of claim 7, wherein said third step includes a process that produces a more isotropic flux than does said first step. 9. The method of claim 1, wherein said metallization metal is aluminum and said barrier metal is titanium. 10. The method of claim 9, wherein said second sputter gas comprises helium. 11. The method of claim 10, wherein said second sputter gas additionally comprises argon. 12. The method of claim 1, wherein said metallization metal comprises copper and said barrier metal comprises tantalum. 13. The method of claim 12, wherein said second sputter gas comprises neon. 14. The method of claim 12, wherein said second sputter gas comprises nitrogen. 15. The method of claim 12, wherein said second sputtering gas comprises helium. 16. The method of claim 15, wherein said second sputtering gas additionally comprises argon. 17. The method of claim 15, wherein said sputter etching step includes biasing a pedestal electrode supporting said substrate to have a voltage of between-100 and-600 VDC. 18. A method of forming in a substrate a first layer comprising a first element having a first atomic mass overlying a second layer comprising a second element having a second atomic mass greater than said first atomic mass, said metallic and baffler layers formed over at least sidewalls of a hole, said method comprising the steps of: a first step of sputter depositing said first layer in a sputter reactor including a target having a target surface area comprising said first element from a plasma that is at least ignited with a first sputter gas; and a second step of sputter etching said first layer with a second sputter gas comprising a gas having a third atomic mass less than said first atomic mass. 19. The method of claim 18, wherein said first sputter gas is argon. 20. The method of claim 18, wherein said first element is a metallization metal and said second element is a baffler metal. 21. The method of claim 20, wherein said metallization metal is copper and said second baffler metal is tantalum. 22. The method of claim 18, wherein said second sputter gas comprises at least one of helium, nitrogen, and neon. 23. A method of depositing a seed layer comprising a metallization metal selected from the group consisting of aluminum and copper in a hole formed in a substrate and having at least sidewalls of said hole covered with a baffler layer of a refractory-based material, said method performed in a plasma sputter reactor including a target having a surface layer comprising said metallization metal, an RF inductive coil within said reactor, and a pedestal electrode for supporting said substrate, said method comprising the steps of: sputter depositing a first layer of said metallization metal while applying a first amount of DC target power to said target, biasing said pedestal with a first amount of RF biasing power to excite a plasma within said reactor to sputter said target, substantially no power being applied to said RF inductive coil during said sputter depositing step; and sputter etching said first layer while biasing said pedestal with a second amount of RF biasing power and applying RF power to said RF inductive coil to excite a sputtering gas into a plasma, substantially no power being applied to said target during said sputter etching step. 24. The method of claim 23, wherein said metallization metal is copper. 25. The method of claim 23, wherein said metallization metal is aluminum. 26. The method of claim 23, wherein said sputtering gas comprises at least one inactive gas selected from the group consisting of helium, nitrogen, neon, and argon. 27. The method of claim 26, wherein said inactive gas is helium. 28. The method of claim 27, wherein said second amount of RF biasing power creates a DC self-bias on said pedestal electrode of between-100 and-600 VDC. 29. A method of depositing a copper seed layer in a hole formed in a substrate and having at least sidewalls of said hole covered with a refractory baffler layer, said method performed in a plasma sputter reactor including a copper target, an RF inductive coil within said reactor, and a pedestal electrode for supporting said substrate, said method comprising the steps of: sputter depositing a first layer of copper while applying a first amount of DC target power to said target to excite a plasma within said reactor to sputter said target, biasing said pedestal with a first amount of RF biasing power, substantially no power being applied to said RF inductive coil during said sputter depositing step; and sputter etching said first layer while biasing said pedestal with a second amount of RF biasing power and applying RF power to said RF inductive coil to excite helium gas into a plasma, substantially no power being applied to said target during said sputter etching step. 30. The method of claim 29, wherein said refractory barrier layer comprises tantalum. 31. The method of claim 29, wherein during said sputter etching step a DC self-bias of between-100 and-600 VDC develops on said pedestal electrode. 32. A process for forming a copper seed layer in a substrate formed with a hole in a dielectric layer and performed in a magnetron plasma sputter reactor including an RF coil surrounding a processing space between a copper target and a pedestal supporting said during at least part of said process of the simultaneous steps of: supplying a sputtering gas into said reactor; providing a first level of RF power to said RF coil; and biasing said pedestal, whereby ions of said noble gas excited into a plasma by said RF coil processes copper deposited onto said substrate; wherein during part of said process said target is not substantially powered while said RF coil is powered. 33. The process of claim 32, wherein said sputtering gas comprises helium. 34. The process of claim 32, wherein said sputtering gas comprises neon. 35. The process of claim 32, wherein said sputtering gas comprises argon. 36. The process of claim 32, wherein said sputtering gas comprises at least two of helium, nitrogen, neon, and argon. 37. The process of claim 32, further comprising the previous step of: biasing said target with sufficient power to sputter material from it onto said substrate while said RF coil is biased if at all with less than said first level of RF power. 38. The process of claim 32, wherein said supplying steps supplies both helium and argon into said reactor and further comprising the simultaneous step of biasing said target to sputter material from it onto said substrate. 39. A method of depositing a copper seed layer in a hole formed in a substrate and having at least sidewalls of said hole covered with a refractory barrier layer, the method performed in a plasma sputter chamber including a copper target, an RF inductive coil within the chamber, and a pedestal electrode for supporting the substrate, the method comprising the steps of: a first step of sputter depositing a first layer of copper on the substrate while supplying argon into the chamber, RF biasing the pedestal, and applying DC power to the target to excite an argon plasma to sputter the target; and sputter etching the first layer while supplying helium into the chamber, RF biasing the pedestal, and applying RF power to said RF inductive coil to excite a helium plasma to sputter etch the substrate. 40. The method of claim 39, further comprising the subsequent step of a second step of sputter depositing a second layer of copper on the substrate while supplying argon into the chamber and applying DC power to the target to excite an argon plasma to sputter the target, less RF biasing being applied to the pedestal in the second step than in the first step.