Exploration charge effect and wafer backside materials correlation to Diamond-Like Carbon wafer table degradation

In DRAM process development history, Wafer table (WT) corrosion is an inevitable problem which mainly affects exposed wafer focus and overlay in exposure machines. In this study, Diamond-Like Carbon (DLC) WT experience of the Vendor Charge Measurements (VCM) and Wafer Load Grid (WLG) characterization elaborated correlation among WT corrosion, charge effect and wafer backside materials, contributing to extend WT lifetime and improve high-volume manufacturing (HVM) stability. Research results indicated CXMT product clustered charge main from pre-lithography process and Lithography back side treatment (BST) process. The difference of wafer backside materials bring friction in varying degrees between wafer and WT. The wafer backside materials with hardness and smooth property induced WT rapid degradation.