Strong and weak quadrupole apertures have been optimized and fabricated for relatively dense O.12~im geometry’s. All of the apertures were optimized using PROLITH/2 simulation software. The apertures were fabricated as fused silica reticles that are inserted at the lens pupil plane. The apertures change the illumination profile that is collected by the condenser lens. Depth of focus (DOF) is increased using quadrupole illumination when trying to resolve specific pitch values.
"Quadrupole Apertures for 193nm Lithography,"
Journal of the Microelectronic Engineering Conference: Vol. 8
, Article 15.
Available at: http://scholarworks.rit.edu/ritamec/vol8/iss1/15