The Ashing step in the 40nm BSI CMOS Image Sensor process flow immediately follows the Sacrificial Lower OCL Etch (Engineering Practice).In advanced image sensor manufacturing, sacrificial organic layers are utilized to planarize deep topography and facilitate controlled etch-back processes P3.Once the structural transfer is complete, it is critical to completely remove any remaining sacrificial polymer, photoresist, and etch-induced fluorocarbon residues P4.Ashing provides the necessary highly