Numerical study of slot-die coating on film formation for different die lip configurations

Slot-die coating is a promising technology for the development of integrated circuits. In this study, we used  ANSYS Fluent, to investigate slot-die coating for different die lip configurations. We compared the coating window results with published experimental data. The results were consistent at low coater speeds and mass flow rates; however, we observed a large discrepancy at the highest speeds and pump flow rates. This could be because the two-dimensional model fails to predicta realistic boundary condition in the spanwise direction. We also implemented a three-dimensional model to predict the uniformity of the slot-die coating for different coating gaps (0.25, 0.3, and 0.35 mm). The results show that the 0.25 mm gap results in the smallest thickness, while the 0.3 mm gap has the best uniformity. We considered different die lip configurations. When the pump flow rate was 1.904 g/s, the coater speed was 0.1 m/s, and the die lip was 0.5 mm upstream and 0.25 mm downstream, the film thickness was 12.2 μm. Under the same conditions, when the die lips were 0.25 mm upstream and 0.5 mm downstream, the film thickness was nearly the same at around 13.2 μm.  The pressure gradient plays an important role in a faster coating process.