Lithography - Microlithography and Nanolithography

Microlithography and Nanolithography

Microlithography and nanolithography refer specifically to lithographic patterning methods capable of structuring material on a fine scale. Typically, features smaller than 10 micrometers are considered microlithographic, and features smaller than 100 nanometers are considered nanolithographic. Photolithography is one of these methods, often applied to semiconductor manufacturing of microchips. Photolithography is also commonly used for fabricating Microelectromechanical systems (MEMS) devices. Photolithography generally uses a pre-fabricated photomask or reticle as a master from which the final pattern is derived.

Although photolithographic technology is the most commercially advanced form of nanolithography, other techniques are also used. Some, for example electron beam lithography, are capable of much greater patterning resolution (sometimes as small as a few nanometers). Electron beam lithography is also important commercially, primarily for its use in the manufacture of photomasks. Electron beam lithography as it is usually practiced is a form of maskless lithography, in that a mask is not required to generate the final pattern. Instead, the final pattern is created directly from a digital representation on a computer, by controlling an electron beam as it scans across a resist-coated substrate. Electron beam lithography has the disadvantage of being much slower than photolithography.

In addition to these commercially well-established techniques, a large number of promising microlithographic and nanolithographic technologies exist or are being developed, including nanoimprint lithography, interference lithography, X-ray lithography, extreme ultraviolet lithography, magnetolithography and scanning probe lithography. Some of these new techniques have been used successfully for small-scale commercial and important research applications. Surface-charge lithography, in fact Plasma desorption mass spectrometry can be directly patterned on polar dielectric crystals via pyroelectric effect, Diffraction lithography.