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An apparatus for wet etching metal from a semiconductor wafer comprises a wafer holder for rotating a wafer and a plurality of nozzles for applying separate flow patterns of etching liquid to the surface of the wafer. The flow patterns impact the wafer in distinct band-like impact zones. The flow pa

An apparatus for wet etching metal from a semiconductor wafer comprises a wafer holder for rotating a wafer and a plurality of nozzles for applying separate flow patterns of etching liquid to the surface of the wafer. The flow patterns impact the wafer in distinct band-like impact zones. The flow pattern of etching liquid from at least one nozzle is modulated during a total etching time control the cumulative etching rate in one local etch region relative to the cumulative etching rate in one or more other local etch regions. Some embodiments include a lower etch chamber and an upper rinse chamber separated by a horizontal splash shield. Some embodiments include a retractable vertical splash shield used to prevent splashing of etching liquid onto the inside walls of a treatment container. An etch-liquid delivery system includes a plurality of nozzle flow paths having corresponding nozzle flow resistances, and a plurality of drain flow paths having corresponding drain flow resistances. Nozzle flow resistances and drain flow resistances are matched so that switching the flow from a nozzle to a corresponding drain flow path does not change the flow rate of etching liquid through other nozzles. A non-wafer-contacting measuring device measures a metal thickness on a rotating semiconductor wafer during metal wet etching by immersing a plurality of electrodes in etching liquid in close proximity to the wafer surface of the rotating wafer and determining electrical resistance between a plurality of electrodes.

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1. A method of removing metal from a semiconductor wafer using localized wet etching, comprising: rotating a semiconductor wafer in a wafer holder;applying a first flow pattern of wet etching solution to a first band-like impact zone of said rotating semiconductor wafer using a first etch nozzle dur

1. A method of removing metal from a semiconductor wafer using localized wet etching, comprising: rotating a semiconductor wafer in a wafer holder;applying a first flow pattern of wet etching solution to a first band-like impact zone of said rotating semiconductor wafer using a first etch nozzle during at least a portion of a total etching time;simultaneously applying a second flow pattern of wet etching solution to a second band-like impact zone of said rotating semiconductor wafer using a second etch nozzle during at least a portion of said total etching time, wherein said first impact zone and said second impact zone are spatially distinct from each other; andselectively controlling a first cumulative etching rate in a first local etch region of said semiconductor wafer relative to a second cumulative etching rate in a second local etch region by modulating said first flow pattern of wet etching solution. 2. The method of claim 1, wherein: said first impact zone and said second impact zone do not overlap. 3. The method of claim 1, wherein: at least one of said first band-like impact zone and said second band-like impact zone has a substantially arced shape and extends completely across said semiconductor wafer substantially concentric with the wafer center. 4. The method of claim 1, wherein: each of said first etch nozzle and said second etch nozzle applies a three-dimensional flow pattern of wet etching solution that extends beyond peripheral edges of the semiconductor wafer. 5. The method of claim 1, wherein: said first etch nozzle modulates said first flow pattern of wet etching solution by ceasing flow of wet etching solution. 6. The method of claim 1, wherein: said first etch nozzle modulates said first flow pattern of wet etching solution by ceasing flow of wet etching solution and then applying deionized water to said first impact zone. 7. The method of claim 1, wherein: said first etch nozzle modulates said first flow pattern of wet etching solution by ceasing flow of wet etching solution and then applying an etching quenchant to said first impact zone. 8. The method of claim 1, wherein: said first etch nozzle modulates said first flow pattern of wet etching solution by changing a flow rate of wet etching solution. 9. The method of claim 1, wherein: said first etch nozzle modulates said first flow pattern of wet etching solution by changing a composition of wet etching solution. 10. The method of claim 1, wherein: said first etch nozzle modulates said first flow pattern of wet etching solution by changing a concentration of wet etching solution. 11. The method of claim 1, wherein: said first etch nozzle modulates said first flow pattern of wet etching solution by changing a shape of said first flow pattern. 12. The method of claim 1, wherein: said first etch nozzle and said second etch nozzle apply wet etching solution substantially normal to the surface of the semiconductor wafer. 13. The method of claim 1, wherein: said first etch nozzle applies a first spray pattern to said first band-like impact zone at an angle in a range of about from 5° to 15° to the surface of the semiconductor wafer so that an inside edge of said first impact zone is offset from the center of said semiconductor wafer by a radial distance in a range of about from 5 mm to 25 mm. 14. The method of claim 1, further comprising: rinsing said etch nozzles using a rinse nozzle when substantially no wet etching solution is flowing through said etch nozzles. 15. The method of claim 1, wherein: said wafer holder, said semiconductor wafer and said first and second etch nozzles are located in a treatment container; and further comprisingrinsing wet etching solution from treatment container walls using a plurality of rinse nozzles. 16. The method of claim 1, wherein said wet etching solution comprises: a complexing agent selected from the group consisting of a bidentate, a tridentate and a quadridentate complexing agent at a concentration in a range of about from 0.01M to 6M; andan oxidizing agent at a concentration in a range of about from 0.2M to about 12M;wherein said wet etching solution has a pH value in a range of about from 6 to 10. 17. The method of claim 1, wherein said wet etching solution comprises: ethylenediamine at a concentration in a range of about from 0.04M to 0.2M; andH2O2 at a concentration in a range of about from 0.2 M to 2M;wherein said wet etching solution has a pH value in a range of about from 8.5 to 10. 18. The method of claim 1, further comprising: forming said wet etching solution by mixing a complexing agent and an oxidizer less than two minutes before applying said wet etching solution to said semiconductor wafer. 19. The method of claim 1, further comprising: heating said wet etching solution by using one or more heat-generating mixing events selected from the group consisting of: dissolution of a complexing agent in water; addition of a pH adjustor to a solution containing a complexing agent; and mixing of a solution of a complexing agent with a solution of an oxidizing agent. 20. The method of claim 1, wherein: at least one of said first band-like impact zone and said second band-like impact zone has a substantially rectangular shape and extends completely across said semiconductor wafer substantially parallel to a wafer diameter. 21. The method of claim 20, wherein: said first impact zone has a radial width in a range of about from 5 mm to 20 mm; andsaid second impact zone has a radial width in a range of about from 5 mm to 20 mm. 22. The method of claim 1, further comprising: rinsing wet etching solution from said semiconductor wafer using a rinse nozzle. 23. The method of claim 22, further comprising: moving said semiconductor wafer between an etch chamber and a rinse chamber; whereinapplying wet etching solution to said semiconductor wafer using a plurality of etch nozzles for selectively modulating a first cumulative etching rate relative to a second cumulative etching rate is performed in said etch chamber; andsaid rinsing wet etching solution from said semiconductor wafer is performed in said rinse chamber after said moving. 24. The method of claim 1, further comprising: measuring a metal thickness on said semiconductor wafer during said applying wet etching solution to said semiconductor substrate using a non-wafer-contacting measuring device. 25. The method of claim 24, wherein: said measuring a metal thickness using said non-wafer-contacting measuring device comprises immersing a plurality of electrodes in wet etching solution in close proximity to the wafer surface of said rotating semiconductor wafer and determining electrical resistance between a plurality of electrodes. 26. The method of claim 1, further comprising: using a nozzle arm to support said first and second etch nozzles and to dispose said first and second etch nozzles substantially above the rotating semiconductor wafer in said wafer holder during localized etching. 27. The method of claim 26, further comprising: moving said nozzle arm to a position in which said nozzle arm and said etch nozzles are not directly above the semiconductor wafer in said wafer holder. 28. The method of claim 26, further comprising: moving said nozzle arm to an etching position in which a plurality of said etch nozzles are substantially aligned with a radius of a semiconductor wafer in said wafer holder. 29. The method of claim 28, further comprising: adjusting the radial position of at least one of said first and second etch nozzles relative to the center of a semiconductor wafer. 30. The method of claim 26, further comprising: moving said nozzle arm in a direction perpendicular to the semiconductor wafer in said wafer holder to change the distance of said first and second etch nozzles from said semiconductor wafer. 31. The method of claim 26, further comprising: adjusting at least one of a plurality of said etch nozzles supported on said nozzle arm to change the distance between said at least one etch nozzle and the semiconductor wafer. 32. The method of claim 26, further comprising: rinsing said nozzle arm and said etch nozzles using a rinse nozzle. 33. A method of removing metal from a semiconductor wafer using localized wet etching, comprising: rotating a semiconductor wafer in a wafer holder positioned in a treatment container;applying a first flow pattern of etching liquid to a first band-like impact zone of said rotating semiconductor wafer using a first etch nozzle during at least a portion of a total etching time;simultaneously applying a second flow pattern of etching liquid to a second band-like impact zone of said rotating semiconductor wafer using a second etch nozzle during at least a portion of said total etching time, wherein said first impact zone and said second impact zone are spatially distinct from each other;selectively controlling a first cumulative etching rate in a first local etch region of said semiconductor wafer relative to a second cumulative etching rate in a second local etch region by modulating said first flow pattern of etching liquid; andrinsing etching liquid from said semiconductor wafer using a rinse nozzle, wherein said wafer holder, said semiconductor wafer, said first and second etch nozzles and said rinse nozzle are located in a treatment container; and further comprisingpositioning a retractable vertical splash shield in an active position while applying said etching liquid to said semiconductor wafer so that said vertical splash shield substantially surrounds said semiconductor wafer in said wafer holder and is located between said wafer holder and an inner wall of said treatment container and is operable to inhibit etching liquid from etch nozzles and from a spinning semiconductor wafer from splashing onto said inner wall; andduring said rinsing, positioning said vertical splash shield in an inactive position so that said vertical splash shield is not proximate to said semiconductor wafer in said wafer holder. 34. A method of removing metal from a semiconductor wafer using localized wet etching, comprising: rotating a semiconductor wafer in a wafer holder positioned in a treatment container;applying a first flow pattern of etching liquid to a first band-like impact zone of said rotating semiconductor wafer using a first etch nozzle during at least a portion of a total etching time;simultaneously applying a second flow pattern of etching liquid to a second band-like impact zone of said rotating semiconductor wafer using a second etch nozzle during at least a portion of said total etching time, wherein said first impact zone and said second impact zone are spatially distinct from each other;selectively controlling a first cumulative etching rate in a first local etch region of said semiconductor wafer relative to a second cumulative etching rate in a second local etch region by modulating said first flow pattern of etching liquid; andpositioning a retractable vertical splash shield in an active position while applying said etching liquid to said semiconductor wafer so that said vertical splash shield substantially surrounds said semiconductor wafer in said wafer holder and is located between said wafer holder and an inner wall of a treatment container housing the semiconductor wafer and, wherein the retractable vertical splash shield is operable to inhibit etching liquid from etch nozzles and from a spinning semiconductor wafer from splashing onto said inner wall.