Electromagnetic energy is emitted from an illumination source of
a lithography device. A portion of the emitted electromagnetic energy passes through
an illumination optics module. The illumination optics module includes a one-dimensional
optical transform element having a pupil plane. An aperture device having an adjustable
aperture is located proximate to the pupil plane so that a portion of the electromagnetic
energy received by the one-dimensional optical transform element passes through
the aperture of the aperture device. The angular distribution of the electromagnetic
energy passing through the illumination optics module is adjusted as a function
of illumination field position using the aperture device, thereby improving line
width control in the lithography device.
