A lithography apparatus having achromatic Fresnel objective (AFO) that combines
a Fresnel zone plate and a refractive Fresnel lens. The zone plate provides high
resolution for imaging and focusing, while the refractive lens takes advantage
of the refraction index change properties of appropriate elements near absorption
edges to recombine the electromagnetic radiation of different energies dispersed
by the zone plate. This compound lens effectively solves the high chromatic aberration
problem of zone plates. The lithography apparatus allows the use of short wavelength
radiation in the 1-15 nm spectral range to print high resolution features as small
as 20 nm.
