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This invention employs a novel approach to the copper metallization of a workpiece, such as a semiconductor workpiece. In accordance with the invention, an alkaline electrolytic copper bath is used to electroplate copper onto a seed layer, electroplate copper directly onto a barrier layer material,

This invention employs a novel approach to the copper metallization of a workpiece, such as a semiconductor workpiece. In accordance with the invention, an alkaline electrolytic copper bath is used to electroplate copper onto a seed layer, electroplate copper directly onto a barrier layer material, or enhance an ultra-thin copper seed layer which has been deposited on the barrier layer using a deposition process such as PVD. The resulting copper layer provides an excellent conformal copper coating that fills trenches, vias, and other microstructures in the workpiece. When used for seed layer enhancement, the resulting copper seed layer provide an excellent conformal copper coating that allows the microstructures to be filled with a copper layer having good uniformity using electrochemical deposition techniques. Further, copper layers that are electroplated in the disclosed manner exhibit low sheet resistance and are readily annealed at low temperatures.

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1. A process for applying a metal structure to a workpiece comprising:providing a first electroplating bath including a source of metal ions as a principal metal species to be deposited during subsequent electroplating, boric acid, and a metal ion complexing agent;providing a workpiece on which one

1. A process for applying a metal structure to a workpiece comprising:providing a first electroplating bath including a source of metal ions as a principal metal species to be deposited during subsequent electroplating, boric acid, and a metal ion complexing agent;providing a workpiece on which one or more microelectronic devices are to be formed;exposing at least one surface of the workpiece to the first electroplating bath; andapplying electroplating power between the at least one surface of the workpiece and an electrode disposed in electrical contact with the first electroplating bath to electroplate the principal metal species onto the at least one surface of the workpiece in an electrolytic first deposition process, wherein power is applied during at least a portion of the first deposition process for a workpiece surface current density of between 1.0 mA/cm 2 and 5.0 mA/cm 2 . 2. The process of claim 1, wherein power is applied during at least a portion of the first deposition process at a workpiece surface current density of about 2.0 mA/cm 2 . 3. The process of claim 1, wherein power is applied at a workpiece surface current density of between 1.0 mA/cm 2 and 5.0 mA/cm 2 over a time period of between 1.0 and 5.0 minutes. 4. The process of claim 1, wherein power is applied in periodic pulses during deposition. 5. The process of claim 4, wherein power is applied in forward pulses having a period of about 2 msec at a 50% duty cycle. 6. The process of claim 1, further comprising depositing additional metal of the same principal metal species onto the metal deposited in the first deposition process using a second deposition process that is different than the first electrolytic deposition process. 7. The process of claim 6, wherein the second deposition process occurs in an acidic electrolytic bath. 8. The process of claim 6, wherein metal is deposited in the second deposition process at a higher rate than in the first deposition process. 9. The process of claim 6, wherein the metal deposited is copper. 10. The process of claim 6, wherein the source of metal ions comprises copper sulfate included at a level of 0.03 to 0.25 M. 11. The process of claim 1, wherein the first electroplating bath comprises an alkaline bath. 12. The process of claim 11, wherein the alkaline bath has a pH of at least 9.0. 13. The process of claim 12, wherein the alkaline bath is pH adjusted with an alkaline agent selected from the group consisting of potassium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide and sodium hydroxide. 14. The process of claim 11, wherein the first electroplating bath includes a conformality increasing agent. 15. The process of claim 14, wherein the conformality increasing agent comprises ethylene glycol. 16. The process of claim 11, further comprising depositing a barrier layer on the surface of the workpiece before the first deposition process. 17. The process of claim 16, wherein metal is plated directly onto the barrier layer in the first deposition process. 18. The process of claim 16, further comprising depositing an ultra-thin seed layer of metal onto the barrier layer before the first deposition process. 19. The process of claim 1, further comprising depositing an ultra-thin seed layer of metal onto the barrier layer before the first deposition process. 20. The process of claim 1, wherein the complexing agent is selected from the group consisting of ED, EDTA, and a polycarboxylic acid. 21. The process of claim 20, wherein the complexing agent is citric acid. 22. The process of claim 1, wherein the source of metal ions comprises copper sulfate, and the complexing agent comprises ED, further comprising tetramethylammonium hydroxide in an amount sufficient to adjust the pH of the solution to at least 9.0. 23. A process for applying a metal structure to a workpiece comprising:providing a first electroplating bath including a source of metal ions as a principal metal species to be deposited during sub sequent electroplating, a metal ion complexing agent and an alkaline agent in an amount sufficient to adjust the pH of the bath to at least 9.0;providing a workpiece on which one or more microelectronic devices are to be formed;exposing at least one surface of the workpiece to the first electroplating bath; andapplying electroplating power between the at least one surface of the workpiece and an electrode disposed in electrical contact with the first electroplating bath to electroplate the principal metal species onto the at least one surface of the workpiece in an electrolytic first deposition process, wherein power is applied during at least a portion of the first deposition process for a workpiece surface current density of between 1.0 mA/cm 2 and 5.0 mA/cm 2 . 24. A process for applying a metal structure to a workpiece comprising:providing a first electroplating bath including a source of metal ions as a principal metal species to be deposited during subsequent electroplating, boric acid, and a metal ion complexing agent;providing a workpiece on which one or more microelectronic devices are to be formed;exposing at least one surface of the workpiece to the first electroplating bath; andapplying electroplating power between the at least one surface of the workpiece and an electrode disposed in electrical contact with the first electroplating bath to electroplate the principal metal species onto the at least one surface of the workpiece in an electrolytic first deposition process, wherein power is applied during at least a portion of the first deposition process in periodic pulses for a workpiece surface current density of between 1.0 mA/cm 2 and 5.0 mA/cm 2 . 25. The process of claim 24, wherein power is applied in forward pulses having a period of about 2 msec at a 50% duty cycle. 26. The process of claim 25, wherein pulsed power is applied for a period of 1.0 to 5.0 minutes. 27. A process for applying a copper structure to a workpiece comprising:providing a workpiece on which one or more microelectronic devices are to be formed;depositing an ultra-thin seed layer of copper onto a surface of the workpiece;providing a first electroplating bath including copper as a source of metal ions as a principal metal species to be deposited during subsequent electroplating and an alkaline agent in an amount sufficient to adjust the pH of the bath to at least 9.0;exposing the surface of the workpiece to the first electroplating bath; andapplying electroplating power between the surface of the workpiece and an electrode disposed in electrical contact with the first electroplating bath to electroplate the principal metal species onto the ultra-thin seed layer in an electrolytic first deposition process, wherein power is applied during at least a portion of the first deposition process for a workpiece surface current density of between 1.0 mA/cm 2 and 5.0 mA/cm 2 .