The ILD 6-4 Deposition step is an intermediate phase in constructing the thick composite inter-layer dielectric (ILD6) in the upper back-end-of-line (BEOL) of a 40nm BSI CMOS Image Sensor P1.Following the Ta-Barrier etch and photoresist ashing at the bondpad level, the ILD structure must be built up incrementally to encapsulate the underlying interconnects and prepare for subsequent planarization and via formation A2.Multi-stage deposition (e (Engineering Practice).g., advancing from ILD 6-3 to