In the 40nm BSI CMOS Image Sensor BEOL flow, the multi-layer ILD 6 stack serves as the foundational integration platform for the Direct Bond Interconnect (DBI) pad (Engineering Practice).Following the deposition of earlier bulk low-k layers (ILD 6-3 and 6-4) and post-ash cleaning, ILD 6-5 is deposited to function as a dense hermetic barrier and structural support layer (Engineering Practice).This layer prepares the substrate for the subsequent ILD 6-6 wafer bonding layer (WBL) deposition and the