Application of surfactant for facilitating benzotriazole removal and inhibiting copper corrosion during post-CMP cleaning

Wafer surface is usually contaminated by organic residues, such as benzotriazole(BTA), after chemical mechanical planarization (CMP). Due to the reason that these organic residuals need to be removed during the post-CMP cleaning process as well as keep the copper corrosion prevented, it is critically important for some large scale industrial applications to develop an effective and low-cost cleaning solution, which will remove the organic residuals and inhibiting corrosion of copper surface. In this work, the effect of surfactant based on alkaline chelating agent was investigated for BTA removal and copper corrosion during post-CMP cleaning. BTA removal was characterized using contact angle measurements and X-ray photoelectron spectroscopy (XPS) analysis. The degree of corrosion of Cu surface was characterized by scanning electron microscope (SEM) and electrochemical techniques. The Cu surface quality after cleaning was characterized by atomic force microscopy (AFM). The defect maps of the 300 mm Cu patterned wafer surface after cleaning were also collected. The experimental results demonstrate that surfactant in the cleaning solution can effectively inhibit the Cu surface corrosion with a lower surface roughness and simultaneously facilitate the removal of BTA residues. The related cleaning mechanism has been studied and proposed based on our experimental results.