Low copper electroplating solutions for fill and defect control
AssigneeNovellus Systems, Inc.
InventorsJian Zhou, Jon Reid
Life of this patent
Estimating the term…
Abstract
Certain embodiments herein relate to a method of electroplating copper into damascene features using a low copper concentration electrolyte having less than about 10 g/L copper 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.
Claims31
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;
- immersing the substrate in an aqueous low copper acid-containing electrolyte comprising less than about 10 grams per liter copper ions and at least one suppressor compound, whereby the low copper electrolyte induces a cathodic overpotential on the seed sufficient to protect the seed from dissolution by acid in the electrolyte during immersion;
- electroplating copper into the features at a current density of about 3 mA/cm2 or less;
- 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;
- immersing the substrate in an aqueous low copper acid-containing electrolyte comprising less than about 10 grams per liter copper ions, at least one suppressor compound and at least one accelerator compound,
- during the immersing, electroplating copper into the features by a bottom-up fill mechanism, wherein the low copper electrolyte permits plating using sufficiently low current density such that the time of plating is adequate 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;
- halide ions;
- one or more suppressor compound;
- one or more accelerator compound;
- and
- the electrolyte having a cloud point above 50° C.
The electrolyte of claim 26, wherein the acid is sulfuric acid.
Dependencies are inferred from the claim text.