The Pre Litho Cleaning step occurs immediately following the deposition of the ILD 6-1 and ILD 6-2 dielectric layers, serving as the critical preparatory phase before the Bond Pad Cavity Photo step A2.Oxide deposition processes inevitably introduce trace particulate contamination and variations in surface morphology that must be mitigated prior to photolithography P2.Unlike earlier pre-litho cleans in this flow that prepare fine-pitch copper interconnects or dense via arrays, this specific step