This article presents the extension of krypton fluoride (KrF) excimer laser lithography. An 0.18 mu m device can be fabricated by KrF excimer laser lithography when weak off-axis illumination is combined with an attenuated phase-shifting mask, a high-performance antireflective layer, and a high-numeral-aperture exposure tool. A 1.0 mu m depth-of-focus can be achieved for 0.18 mu m rule logic patterns. The weak off-axis illumination can reduce the influences of the secondary peak in the high-duty periodic patterns, and retain the depth-of-focus for isolated patterns when it is used in combination with an attenuated phase-shifting mask. A high-performance antireflective layer can increase the depth-of-focus because a uniformly exposed area in the photoresist can be formed when the light reflected from the substrate is eliminated.