Copper electrodeposition solution and process for high aspect ratio patterns
Assigneeaveni
InventorsLaurianne Religieux, Vincent Mevellec, Mikailou Thiam
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Abstract
The present invention relates to an electrolyte composition for depositing copper on a conductive surface. The composition contains a combination of 2,2′-bipyridine, imidazole, tetra-ethyl-ammonium, and a complexing agent for copper. This electrolyte makes it possible to manufacture small size copper interconnects without any void and with a filling speed that is compatible with industrial constrain. The invention also concerns a process for filling cavities with copper, and a semiconductor device that is obtained according to this process.
Claims11
An electrolyte having a pH being from 8.5 to 9.5, that is intended for electrodeposition of copper on a metal substrate, said electrolyte comprising, in an aqueous solution, from 0.4 to 50 mM of a mixture of at least two copper (II) ion complexes including:
- a first copper (II) ion complex or combination of complexes selected from the group consisting of:
- a complex of copper (II) ions with 2,2′-bipyridine and imidazole;
- a combination of a complex of copper (II) ions with 2,2′-bipyridine and a complex of copper (II) ions with imidazole;
- a combination of a complex of copper (II) ions with 2,2′-bipyridine and a complex of copper (II) ions with 2,2′-bipyridine and imidazole;
- a combination of a complex of copper (II) ions with imidazole and a complex of copper (II) ions with 2,2′-bipyridine and imidazole;
- and
- a combination of a complex of copper (II) ions with 2,2′-bipyridine, a complex of copper (II) ions with imidazole, and a complex of copper (II) ions with 2,2′-bipyridine and imidazole;
- and
- a second copper (II) ion complex that includes a complexing molecule being tartaric acid or ethylenediamine, wherein said complexing molecule is in an acidic or basic form when complexed with the copper,
- wherein the electrolyte is a result of mixing a first solution comprising the first copper (II) ion complex or combination of complexes with a second solution comprising the second copper (II) ion complex,
- said first solution results from mixing copper (II) ions, 2,2′-bipyridine, and imidazole, wherein a molar ratio between a 2,2′-bipyridine concentration and an imidazole concentration is in the range from 4/1 to 1/4, and
- said second solution results from mixing copper (II) ions with the complexing molecule.
An electrochemical process for copper filling of patterns that are hollowed-out in a dielectric substrate, and have at least one exposed surface of a metal seed layer, wherein said patterns have an opening dimension that is from 5 nm to 45 nm and a form factor that is from 3:1 to 20:1, said process comprising the steps of:
- bringing the exposed surface into contact with an electrolyte, the electrolyte having a pH being from 8.5 to 9.5, that is intended for electrodeposition of copper on a metal substrate, said electrolyte comprising, in an aqueous solution, from 0.4 to 50 mM of a mixture of at least two copper (II) ion complexes including:
- a first copper (II) ion complex or combination of complexes selected from the group consisting of:
- a complex of copper (II) ions with 2,2′-bipyridine and imidazole;
- a combination of a complex of copper (II) ions with 2,2′-bipyridine and a complex of copper (II) ions with imidazole;
- a combination of a complex of copper (II) ions with 2,2′-bipyridine and a complex of copper (II) ions with 2,2′-bipyridine and imidazole;
- a combination of a complex of copper (II) ions with imidazole and a complex of copper (II) ions with 2,2′-bipyridine and imidazole;
- and
- a combination of a complex of copper (II) ions with 2,2′-bipyridine, a complex of copper (II) ions with imidazole, and a complex of copper (II) ions with 2,2′-bipyridine and imidazole;
- and
- a second copper (II) ion complex that includes a complexing molecule being tartaric acid or ethylenediamine, wherein said complexing molecule is in an acidic or basic form when complexed with the copper, and
- polarizing the exposed surface with a cathodic electric current and allowing the electrodeposition of copper onto the exposed surface, for a time sufficient to completely fill patterns with a copper deposit that comprises no void.
Dependencies are inferred from the claim text.