Characterization Of Leveling Modes On I-Line Stepper

The following study summarizes a thorough work in characterization the effects of different leveling modes in step-and-repeat exposure tool NSR-2205i11D on photolithography process parameters. The experimental work consisted on flatness measurements using the focus system of the stepper, critical dimensions measurements on Hitachi SEM 8600 and leveling sensor images on CCD camera. The study was performed on production wafers at via and metal layers and deal with phenomena that are related to the layout of products and do not appear on bare wafers. The conclusion that came out from this study is that standard leveling mode may have reduced performance due to misleading defraction pattern on its sensor, and optimal setting for the leveling mode should be made for each product and layer solely.