Synergistic effects of PBTCA and ABO on the chemical mechanical polishing of titanium barrier layers in TSV application

The chemical mechanical polishing (CMP) process for the titanium (Ti) barrier layer in Through-Silicon Via (TSV) technology is crucial for the fabrication of advanced 3D and 2.5D integrated circuit (IC) chip packaging. A major challenge in this process is achieving a high Ti removal rate while carefully optimizing the selectivity ratio between Ti and copper (Cu). This study rationally selected 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) as a complexing agent and α-benzoin oxime (ABO) as a corrosion inhibitor in CMP for TSV Ti-based barrier layers. A combined experimental and theoretical approach was used to explore the CMP effects of the two reagents. The experimental results demonstrate that PBTCA significantly enhances the Ti removal rate, while the adsorption of ABO on the Cu surface mitigates the corrosion caused by PBTCA and effectively improved the surface quality of both Cu and Ti. Density Functional Theory (DFT) calculations were performed to analyze the interaction between PBTCA and ABO molecules at the atomic level. This study presents an effective method for removing Ti barrier layers from TSV by using PBTCA and ABO synergistically, providing a practical and effective solution for barrier layer CMP in advanced IC packaging applications.