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Cu Interconnection Formation for High Reliability and Cu Low Resistance

IP.com Disclosure Number: IPCOM000223280D
Publication Date: 2012-Nov-15
Document File: 4 page(s) / 110K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method to supply impurity atoms from an impurity atom source film formed on top of plated Cu.

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Cu Interconnection Formation for High Reliability and Cu Low Resistance

As the device dimension shrinks, the interconnect dimension also shrinks, but the current density does not decrease. As a result, the Cu interconnects face electromigration problems. In order to resolve this problem, Cu alloys such as CuAl and CuMn are used. The impurity atoms such as MN and Al are usually given as a dopant in the Cu seed layer and then diffuse through the plated Cu to reach the Cu top surface during heating processes to form the impurity segregated Cu top surface area. However, as the interconnect width gets smaller and smaller, it becomes more difficult for the Cu interconnects to have the amount of impurity atoms required for improvement of EM performance without extra increase in the Cu line resistance due to the impurity scattering of electrons.

The disclosed solution is a method to supply impurity atoms from an impurity atom source film formed on top of plated Cu. Such a source film is formed by either physical vapor deposits (PVD) or plating on top of plated Cu film. After the formation of the source film, a thermal process is given to drive the diffusion of the impurity atoms into the plated Cu. After the diffusion process, the chemical-mechanical planarization (CMP) is performed to remove the source film and unnecessary plated Cu layer, leaving Cu remaining only in trenches and vias.

Then, a dielectric cap layer is deposited on top. During the cap formation process...