The ILD 3-1 SiCN Etch step is a critical back-end-of-line (BEOL) process responsible for opening the dielectric barrier and etch stop layer (SiCN) at the bottom of Via 3 to expose the underlying Metal 3 interconnect, following the structural integration principles described in A2.In the 40nm node, low-k interlayer dielectrics (ILD) are utilized to reduce resistance-capacitance (RC) delays, while dense amorphous silicon carbonitride (a-SiCN:H) serves as both an etch stop and a copper capping laye