Optimization of Bevel Clean in Back End of Line Passivation Module

In the back end of line (BEOL) passivation module, keeping the wafer's bevel clean is crucial to avoid problems during trench etching in the Metpass film stack. The current process involves using backside chemicals dispensing while the wafer spins, but it's not very effective. It is time-consuming and struggles to remove metal, especially tantalum (Ta), from the bevel. This inefficiency leads to excessive chemical use and increases the risk of issues in subsequent trench etching steps. To address this, our study investigates the details of etch rates, Clean Bevel Edge (CBE), and the efficiency of bevel cleaning. This deep dive allows us to optimize the existing process. As a result, we've managed to cut down the processing time by a third while significantly improving the removal of metal deposits from the wafer bevel. This optimization not only enhances operational efficiency but also substantially reduces the risk in the subsequent trench etching steps, making the overall process more reliable and resource efficient.