Method to improve planarity of electroplated copper
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsShih-Wei Chou, Ming-Hsing Tsai, Ming-Wei Lin
Life of this patent
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Abstract
Narrow trenches in a substrate tend to fill more rapidly than wide trenches This results in a non-planar surface once all trenches have been filled. The present invention solves this problem by performing the electro-deposition in two steps. The plating bath used during the first step, is optimized for filling narrow trenches while the plating bath used during the second step, is optimized for filling wide trenches. The net result is a final layer having a planar surface, with all trenches being properly filled.
Claims24
A process to form damascene structures, comprising:
- providing a substrate having an upper surface in which are a plurality of trenches that have at least two different widths, said trenches having a conductive surface;
- providing a first electrolytic solution comprising a comparatively short chain polymer to trenches having a narrower width of the two different widths, and a second electrolytic solution comprising a comparatively long chain polymer to trenches having a wider width of the two different widths;
- electroplating from said first solution a sufficient thickness of a metal to overfill all narrower trenches while under-filling all wider trenches;
- and
- then electroplating from said second solution a sufficient thickness of said metal to overfill all trenches.
A process for filling trenches with copper, comprising:
- providing a silicon wafer having an upper surface in which are a plurality of trenches that have at least two different widths, all trenches being lined with a conductive barrier layer;
- providing an aqueous solution that comprises at least one copper salt;
- forming a first plating solution that contains a first concentration, in said aqueous solution, of a first accelerator additive;
- forming a second plating solution that contains a second concentration, in said aqueous solution, of a second accelerator additive, said second concentration being greater than said first concentration;
- in a first bath that contains said first plating solution, electroplating onto said upper surface a first thickness of copper that is sufficient to overfill all trenches whose width is less than an amount while under-filling all trenches whose width is greater than said amount;
- and
- then transferring said wafer to a second bath that contains said second plating solution and electroplating on the wafer a second thickness of copper that is sufficient to overfill all trenches.
A Process for filling trenches with copper, comprising:
- providing a silicon wafer having an upper surface in which are a plurality of trenches that have at least two different widths, all trenches being lined with a seed layer;
- providing an aqueous solution that comprises at least one copper salt;
- forming a first plating solution that contains a first concentration, in said aqueous solution, of a first accelerator additive;
- forming a second plating solution that contains a second concentration, in said aqueous solution, of a second accelerator additive, said second concentration being greater than said first concentration;
- in a first bath that contains said first plating solution, electroplating onto said seed layer a first thickness of copper that is sufficient to overfill all trenches whose width is less than an amount while under-filling all trenches whose width is greater than said amount;
- and
- then transferring said wafer to a second bath that contains said second plating solution and electroplating on the wafer a second thickness of copper that is sufficient to overfill all trenches.
Dependencies are inferred from the claim text.