Copper electroplating process for uniform across wafer deposition and void free filling on semi-noble metal coated wafers
First Claim
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1. A method for depositing a copper seed layer comprising:
- providing a semiconductor wafer having a semi-noble metal layer thereon; and
depositing the copper seed layer on the semi-noble metal layer using an electroplating process with an electrolyte comprising a copper salt and a copper complexing agent, wherein the electrolyte is substantially free of chemical species that are corrosive to the metal layer, and wherein the electrolyte has a pH of about 8.5 to 13.5.
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Abstract
Disclosed are methods of depositing a copper seed layer to be used for subsequent electroplating a bulk-layer of copper thereon. A copper seed layer may be deposited with different processes, including CVD, PVD, and electroplating. With electroplating methods for depositing a copper seed layer, disclosed are methods for depositing a copper alloy seed layer, methods for depositing a copper seed layer on the semi-noble metal layer with a non-corrosive electrolyte, methods of treating the semi-noble metal layer that the copper seed layer is deposited on, and methods for promoting a more uniform copper seed layer deposition across a semiconductor wafer.
88 Citations
22 Claims
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1. A method for depositing a copper seed layer comprising:
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providing a semiconductor wafer having a semi-noble metal layer thereon; and depositing the copper seed layer on the semi-noble metal layer using an electroplating process with an electrolyte comprising a copper salt and a copper complexing agent, wherein the electrolyte is substantially free of chemical species that are corrosive to the metal layer, and wherein the electrolyte has a pH of about 8.5 to 13.5. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for depositing a copper seed layer comprising:
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providing a semiconductor wafer having a semi-noble metal layer thereon; applying forward and reverse current pulses to the semi-noble metal layer using a process with an electrolyte to treat the metal layer and thereby improve copper seed layer nucleation and coverage, wherein an efficiency of a forward current pulse is about 40% to 80%, wherein the forward current pulse deposits at least about 2.5 monolayers of copper on the metal layer, wherein an efficiency of a reverse current pulse is greater than about 80%, and wherein the reverse current pulse strips off substantially all of the copper deposited during the forward current pulse; and depositing the copper seed layer on the semi-noble metal layer using an electroplating process with the electrolyte by applying a forward current. - View Dependent Claims (10, 11, 12)
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13. A method for depositing a copper seed layer comprising:
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providing a semiconductor wafer having a semi-noble metal layer thereon, the semiconductor wafer having an edge and a center; depositing the copper seed layer on the semi-noble metal layer using an electroplating process with an electrolyte including a copper salt and a copper complexing agent, wherein a voltage across the metal layer is higher at the edge of the wafer than at the center of the wafer due to a terminal effect, and wherein a total current density approaches or surpasses a limiting copper current density at the edge of the wafer, a copper current density being a contribution of copper reduction to the total current density, thereby promoting a more uniform deposition rate across the metal layer. - View Dependent Claims (14, 15, 16)
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17. A method for depositing a copper alloy seed layer comprising:
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providing a semiconductor wafer having a semi-noble metal layer thereon; depositing the copper alloy seed layer on the semi-noble metal layer using an electroplating process with a first electrolyte including; a copper salt and a copper complexing agent, and a salt of an alloying element, the alloying element selected from;
cobalt, nickel, and silver; anddepositing a bulk-layer of copper on the copper alloy seed layer using an electroplating process with a second electrolyte. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification