Abstract

The evolution of integrated circuits (ICs) has been dominated by the idea of scaling down its basic constituent-the metal-oxide- semiconductor (MOS) field-effect transistor (FET). In turn, this has required the development of suitable lithographic techniques for its definition on smaller and smaller length scales. There are several generations of lithographic techniques, usually classified according to the technology required for the definition of the wanted features on photo- or electro-sensitive materials (resists): standard photolithography (436 nm, Hg g-line; refractive optics), deep ultraviolet (DUV) photolithography (193 nm, ArF excimer laser; refractive optics), immersion DUV photolithography (refractive optics), extreme ultraviolet (EUV) photolithography (13.5 nm, plasma-light source; reflective optics), and electron beam (EB) lithography (electron wavelength controlled by the energy, typically in the interval 10⁻³ to 10⁻² nm).