Figure would be provided
Figure 1 shows that the most important factor in lithography is foot contrast. Low contrast leaves a large region (CAT) where resist solubility is uncertain (chaotic area), which causes unresolvable patterns, LER/LWR issues, and pattern collapse (collapse may be due to affinity imbalance).
Figure 2 shows examples of a CAT plot for two stacks of low optical reflectivity and high optical foot contrast. Low reflectivity gives higher CAT, and is further deteriorated as the image approaches the forbidden pitch, while a high foot contrast stack keeps good CAT value across all pitches. Experimental results agree well with the calculations, which will be included in the full paper.
Figure 3 is a CAT contour map versus resist and Si-HM thickness for a L/P=40/100 nm pattern. Additional CAT plots will be included in the full paper.
Figure 1. Optical distribution of a 40-nm dense line cross-section and resist contrast curve for CAT calculation.
Figure 2. CAT plots comparing two stacks, low reflectivity and high foot contrast
Figure 3. CAT contour map versus resist and Si-HM thickness.
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