Patent ID: 7384725

Claim:
A method of forming a plurality of contact holes in a contact layer of an integrated circuit device, wherein the plurality of contact holes includes a plurality of regularly spaced contact holes having a first pitch along a first direction and a plurality of semi-isolated contact holes having a second pitch along a second direction, said method comprising: providing a photoresist layer over the contact layer; exposing the photoresist layer to a double-dipole illumination source which transmits light energy through a mask having a pattern corresponding to a desired contact hole pattern, the exposing resulting in the desired contact hole pattern being transferred to the photoresist layer; wherein the double-dipole illumination source includes a first dipole aperture, said first dipole aperture being oriented and optimized for patterning the regularly spaced contact holes, and a second dipole aperture, said second dipole aperture being oriented substantially orthogonal to the first dipole aperture and optimized for patterning the plurality of semi-isolated contact holes, wherein the first dipole aperture and the second dipole aperture have at least one of (i) different sizes or (ii) different spacings; and etching the contact layer using the patterned photoresist layer.