In the 40nm BSI CMOS Image Sensor process flow, the Pre Litho Cleaning step within the ILD2 module acts as a critical bridge between the ILD 2-2 Deposition and the Via 2 photolithography stages (Engineering Practice).Semiconductor lithography relies on forming three-dimensional relief images in a light-sensitive polymer to define patterns for subsequent etching A1.To achieve optimal pattern fidelity, the freshly deposited inter-level dielectric (ILD) must be completely free of airborne molecular