Low copper/high halide electroplating solutions for fill and defect control
AssigneeNovellus Systems, Inc.
InventorsJian Zhou, Jonathan David Reid, Erik A. Edelberg
Life of this patent
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Abstract
Certain embodiments herein relate to a method of electroplating copper into damascene features using a low copper, high halide concentration electrolyte having between about 4-10 g/L copper ions, between about 150-400 ppm halide ions, and about 2-15 g/L acid. Using the low copper electrolyte produces a relatively high overpotential on the plating substrate surface, allowing for a slow plating process with few fill defects. The low copper electrolyte may have a relatively high cloud point. The use of a relatively high halide ion concentration may promote improved nucleation on a seed layer, resulting in fewer and less significant voids within the features.
Claims26
A method of plating copper into damascene features, comprising:
- receiving a substrate having a seed thickness of about 200 nanometers, on average, or thinner;
- electrically biasing the substrate while immersing the substrate in an aqueous low copper acid-containing electrolyte comprising (i) between about 4-10 grams per liter copper cations, (ii) between about 150-400 ppm chloride ions, and (iii) at least one suppressor compound, whereby the electrolyte induces a cathodic overpotential on the seed sufficient to protect the seed from dissolution by acid in the electrolyte during immersion;
- electroplating copper in a process comprising:
- (a) a first plating phase to fill the substrate features with copper via a bottom-up fill mechanism, wherein a first current density during the first plating phase is between about 0.5-10 mA/cm2, and
- (b) a second plating phase to deposit an overburden layer of copper on the substrate, wherein a second current density during the second plating phase is greater than the first current density, and wherein the first and second plating phases are part of a single electroplating process;
- and
- removing the substrate from the electrolyte.
A method of plating copper into damascene features, comprising:
- receiving a substrate having a seed thickness of about 200 nanometers, on average, or thinner;
- electrically biasing the substrate while immersing the substrate in an aqueous low copper acid-containing electrolyte comprising (i) between about 4-10 grams per liter copper ions, (ii) between about 150-400 ppm chloride ions, (iii) at least one suppressor compound, and (iv) at least one accelerator compound,
- during the immersing, electroplating copper into the features by a bottom-up fill mechanism at a first current density, wherein electroplating occurs sufficiently slowly in the electrolyte at the first current density to allow the suppressor and accelerator to adsorb onto the seed and thereby enable bottom-up fill during immersion;
- and
- removing the substrate from the electrolyte.
An electrolyte comprising:
- between about 1 and 10 grams per liter copper cations;
- between about 2 and 15 grams per liter acid;
- between about 150-400 ppm chloride ions;
- one or more suppressor compound;
- one or more accelerator compound;
- and
- the electrolyte having a cloud point above 50° C.
Dependencies are inferred from the claim text.