Fabrication tolerance analysis of grating mask for pattern-specific off-axis illumination

摘要

In this paper, the effectiveness of grating mask proposed previously was evaluated for line and space patterns, and its fabrication tolerance was analyzed with aerial image simulation. The structure of grating mask was determined from the local features of Cr patterns. It was verified that grating mask could provide locally matched oblique illumination for specific patterns written on the Cr mask. When the fabrication errors of ±10% were randomly introduced into both the widths and the phases of phase gratings in the grating mask, the resulting aerial image showed the CD variation of 15.5%. In order to reduce CD variation to 5% and less, width and phase errors should be maintained to be less than 3.2% and 7.2%, respectively.