Patent ID: 8917379

Claim:
A method, comprising: providing multipolar illumination in a pupil surface of an illumination system; and using the multipolar illumination to image a first sub-pattern of a pattern onto a layer of a radiation-sensitive material of a substrate, the first sub-pattern including a plurality of first features extending in a first direction and spaced apart essentially periodically at a predominant periodicity length P in a second direction perpendicular to the first direction, and the multipolar illumination comprising at least one substantially dipolar intensity distribution having two illumination poles positioned on a pole orientation axis substantially parallel to the second direction and spaced apart from each other, wherein the poles of the dipolar intensity distribution each have an azimuthal width defined by a pole angle θ, and a pole area A POLE according to: 0.6< A POLE /A OPT <1.1 where A OPT =θ−sin(θ) and where cos(θ/2)=λ/(2*P*NA), λ is a nominal operation wavelength of radiation used, and NA is an image-side numerical aperture of a projection optical system used, and the poles of the dipolar intensity distribution have a generally biconvex pole shape defined by a convex polygon having four or more sides, and some of the sides include angles are significantly larger than 90°.