Standing waves phenomena in a resist laid on a reflective substrate give rise, when resist thickness changes, to variations of linewidths to be transferred by projection printing. We have attempted to display all parameters such as wafer reflectivity, numerical aperture of the lens, spatial coherence of illumination, resist thickness, and their effect on linewidth variations. We demonstrate the possibility to transfer, onto a strongly reflective substrate such as aluminium, lines and spaces 1 μm wide over steps 0.5 μm high, through a CERCO 5 X TULIPE lens, if the resist layer is ≃ 2 μm thick, and if the illumination is spatially coherent