In the 40nm BSI CMOS Image Sensor flow, the Light Shield (LS) Grid requires precise patterning to prevent optical crosstalk between adjacent pixels (Engineering Practice).Following the "Mid Vertical Grid Trench - Photo" step, the lithographic pattern must be transferred through intermediate layers before etching the underlying grid material (Engineering Practice).The "Lower OCL Coating Etch" specifically targets the organic planarization layer (OPL) or anti-reflective coating that was deposited