2000 Volume 120 Issue 12 Pages 1889-1893
In the lithographic processes of VLSI's, high setting accuracies between masks and wafer are required. The methods using moiré signals obtained by gratings were found to give very high alignment accuracies. In this paper, influences of the inclination of gratings for the alignment accuracies in modified and differential moiré systems have been investigated. The moiré signals and the alignment point have been calculated using computer simulation. As a result, it has been shown that the effects are small and the inclinations do not affect alignment accuracies in the moiré alignment systems.
The transactions of the Institute of Electrical Engineers of Japan.C
The Journal of the Institute of Electrical Engineers of Japan