CMP Slurry Deionization for Defect-Reduced Wafer Planarization

The patent applies preliminary action by performing capacitive deionization treatment on the CMP slurry before the actual CMP process. The deionization module removes metallic ions from the slurry in advance, preventing their deposition on the wafer surface during planarization. This pre-treatment ensures that the CMP process achieves surface flatness without generating the harmful ion deposition effect.

The patent extracts the harmful metallic ions from the CMP slurry using a capacitive deionization module. The module contains electrodes that create an electric field to attract and remove ions from the slurry flow. By extracting these ions before they contact the wafer, the system maintains the beneficial planarization effect while eliminating the harmful ion deposition that causes humps and defects.

The patent merges the ion removal function with the existing CMP process by integrating a capacitive deionization module into the slurry delivery system. Instead of adding a separate ion removal step, the deionization is performed in-line as part of the slurry preparation, combining two functions (planarization and ion removal) into a single integrated process flow. This maintains device yield improvement while minimizing additional processing complexity.

The capacitive deionization module acts as an intermediary component between the slurry reservoir and the CMP contact point. It mediates the slurry by removing ions without requiring changes to the fundamental CMP process steps. The module is positioned in the slurry flow path, allowing it to treat the slurry continuously without interrupting the CMP workflow, thus improving yield without significantly increasing process complexity.