关键词: 铜凸块, 均匀性, 垂直式电镀, COMSOL仿真, 阳极屏蔽板

Abstract: To address the challenge of uniformity control in copper pillar bump electrodeposition for 200 mm wafers in vertical plating equipment, a three-dimensional multiphysics coupled model of the plating cell was developed using COMSOL Multiphysics by employing the secondary current distribution coupled with the electrode shell, that considered the dynamic variation of seed layer resistance during the electrodeposition process. The non-uniformity (NU%) was adopted as the evaluation metric for the deposition thickness distribution on the wafer, actual electroplating experiments were conducted and the simulation results were consistent with the experimental results. The simulated NU% of 8.35%, while the experimental value was 9.17%, validating the accuracy of the model. Furthermore, the aperture distribution and the quantity on the anode shield plate was optimized, reducing the NU% to 5.52% in the simulation; subsequently, the electroplating experiments were carried out with the optimized shield plate, yielding a uniformity of 6%, which satisfies the wafer level plating specification. The model coupled with secondary current distribution–electrode shell can accurately predict the uniformity of copper pillar bump electroplating, and the analysis results can serve as the theoretical basis for the development of vertical plating system and the process optimization of the anode shield.

Key words: copper pillar bump, uniformity, vertical plating, COMSOL simulation, anode shield plate