Application of alkaline polishing solution in inhibition of galvanic couple corrosion of copper-tantalum barrier layer

Abstract

The invention belongs to the field of chemically mechanical polishing, and in particular, relates to an application of an alkaline polishing solution in inhibition of galvanic couple corrosion of a copper-tantalum barrier layer; the alkaline polishing solution takes a polyhydroxy polyamino compound as a chelating agent and a pH regulator; the mass percentage of the polyhydroxy polyamino compound in the alkaline polishing solution is 0.1%-2%, and the pH value of the alkaline polishing solution is 9-10.5; the polyhydroxy polyamino compound is formed by mixing one or more of hydroxyethyl ethylenediamine, tetrahydroxyethyl-ethylene diamine and triethanolamine. The special hydroxyl and amino containing compound is added in the alkaline polishing solution to be used as a chelating agent, the chelating agent makes the potential of copper in the polishing solution reduced, a passivation layer is formed on the surface of tantalum, and the potential of tantalum in the polishing solution is reduced in a smaller degree, so that the purpose of reducing the potential difference between copper and tantalum is achieved, the corrosion current is reduced, and the corrosion rate is controlled.

Description

technical field [0001] The invention belongs to the field of chemical mechanical polishing, and in particular relates to the application of an alkaline polishing solution in inhibiting galvanic corrosion of a copper-tantalum barrier layer. Background technique [0002] After the double damascene process replaces the traditional metal etching process, in order to prevent Cu ions from entering SiO 2 Impurities become in the medium, and a diffusion barrier layer needs to be deposited on the surface of the medium before Cu electroplating. The barrier layer (such as Ta / TaN) has stable thermal properties and low film resistivity, which can effectively prevent the diffusion of Cu ions to the dielectric layer and improve the adhesion between Cu and the dielectric. With the continuous reduction of device feature size, the continuous improvement of integration level and the continuous increase of wiring layers in GLSI (Great Large Scale IC, very large scale integrated circuit), chemi...

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Problems solved by technology

They proposed that when the pH is 4, the galvanic corrosion can be inhibited by using the inhibitor benzotriazole (BTA) with large side effects, but the desired effect cannot be achieved, and the existence of BTA makes cleaning after CMP difficult and easy Cause organic contamination and affect device reliability

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