In the 40nm Backside Illuminated (BSI) CMOS Image Sensor process flow, the Upper Grid Seal Layer Etch is a critical step within the BONDPAD module P2.Positioned immediately after the Bond Pad Opening 2 photoresist patterning, this step selectively removes the protective upper grid seal material overlying the peripheral bond pads and optical pads P2.Unlike earlier oxide grid seal layer etches (such as step #323) which define the high-resolution pixel-level isolation grid itself, this specific ste