Following the chemical mechanical polishing (CMP) and cleaning of Metal 4, ILD 4-1 is deposited to serve as an initial layer or etch stop, immediately preparing the surface for the bulk ILD 4-2 deposition P4.The primary function of this bulk dielectric is to physically isolate Metal 4 from the subsequent Metal 5 layer and to structurally house the Via 4 interconnects A2.As device scaling heavily reduces interconnect pitch, minimizing the resistance-capacitance (RC) delay becomes a critical prior