Barrier and electroplating seed layer
First Claim
1. A method of forming a conductive structure in an opening in a partially fabricated integrated circuit, comprising:
- initially sputtering a metal target in the presence of an amount of nitrogen source gas, thereby forming a metal nitride layer in the opening;
reducing a flow rate of the nitrogen source gas linearly with time;
further sputtering the metal target after reducing the amount of nitrogen source gas to form a substantially metal layer over the metal nitride layer in the opening, the metal layer having a top surface; and
electroplating a second metal onto the top surface of the metal layer.
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Accused Products
Abstract
A barrier layer material and method of forming the same is disclosed. The method includes depositing a graded metal nitride layer in a single deposition chamber, with a high nitrogen content at a lower surface and a high metal content at an upper surface. In the illustrated embodiment, a metal nitride with a 1:1 nitrogen-to-metal ratio is initially deposited into a deep void, such as a via or trench, by reactive sputtering of a metal target in nitrogen atmosphere. After an initial thickness is deposited, flow of nitrogen source gas is reduced and sputtering continues, producing a metal nitride with a graded nitrogen content. After the nitrogen is stopped, deposition continues, resulting in a substantially pure metal top layer. This three-stage layer includes a highly conductive top layer, upon which copper can be directly electroplated without a separate seed layer deposition. Advantageously, native oxide on the top metal surface can be cleaned in situ by reversing polarity in the electroplating solution just prior to plating.
61 Citations
21 Claims
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1. A method of forming a conductive structure in an opening in a partially fabricated integrated circuit, comprising:
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initially sputtering a metal target in the presence of an amount of nitrogen source gas, thereby forming a metal nitride layer in the opening;
reducing a flow rate of the nitrogen source gas linearly with time;
further sputtering the metal target after reducing the amount of nitrogen source gas to form a substantially metal layer over the metal nitride layer in the opening, the metal layer having a top surface; and
electroplating a second metal onto the top surface of the metal layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of forming a wiring element with a barrier/seed layer in an integrated circuit, comprising:
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depositing an initial metal nitride layer having a first nitrogen content into an opening in an interlevel dielectric of a substrate assembly, the opening comprising sidewalls and a floor;
depositing a second metal nitride layer directly onto the initial metal nitride layer, the second metal nitride having a second nitrogen content lower than the first nitrogen content;
depositing a substantially metal seed layer directly onto the second metal nitride layer, wherein depositing the initial metal nitride layer, the second metal nitride layer and the metal seed layer are all conducted in situ without removing the substrate assembly from a deposition chamber;
electroplating copper directly onto the substantially metal seed layer; and
precleaning the metal seed layer prior to electroplating, wherein precleaning comprises immersing the substrate assembly in a solution and applying a potential. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification