Microlithography is a general name for any manufacturing process that can create a minutely patterned

thin film A thin film is a layer of material ranging from fractions of a nanometer (monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many ap ...

of protective materials over a substrate, such as a

silicon Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic tab ...

wafer A wafer is a crisp, often sweet, very thin, flat, light and dry biscuit, often used to decorate ice cream, and also used as a garnish on some sweet dishes. Wafers can also be made into cookies with cream flavoring sandwiched between them. They ...

, in order to protect selected areas of it during subsequent

etching Etching is traditionally the process of using strong acid or mordant to cut into the unprotected parts of a metal surface to create a design in intaglio (incised) in the metal. In modern manufacturing, other chemicals may be used on other types ...

, deposition, or implantation operations. The term is normally used for processes that can reliably produce features of microscopic size, such as 10

micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

s or less. The term nanolithography may be used to designate processes that can produce

nanoscale The nanoscopic scale (or nanoscale) usually refers to structures with a length scale applicable to nanotechnology, usually cited as 1–100 nanometers (nm). A nanometer is a billionth of a meter. The nanoscopic scale is (roughly speaking) a lo ...

features, such as less than 100

nanometre 330px, Different lengths as in respect to the molecular scale. The nanometre (international spelling as used by the International Bureau of Weights and Measures; SI symbol: nm) or nanometer (American and British English spelling differences#-re ...

s. Microlithography is a

microfabrication Microfabrication is the process of fabricating miniature structures of micrometre scales and smaller. Historically, the earliest microfabrication processes were used for integrated circuit fabrication, also known as "semiconductor manufacturing" ...

process that is extensively used in the

semiconductor industry The semiconductor industry is the aggregate of companies engaged in the design and fabrication of semiconductors and semiconductor devices, such as transistors and integrated circuits. It formed around 1960, once the fabrication of semiconduct ...

and also manufacture

microelectromechanical systems Microelectromechanical systems (MEMS), also written as micro-electro-mechanical systems (or microelectronic and microelectromechanical systems) and the related micromechatronics and microsystems constitute the technology of microscopic devices, ...

Processes

Specific microlithography processes include: *

Photolithography In integrated circuit manufacturing, photolithography or optical lithography is a general term used for techniques that use light to produce minutely patterned thin films of suitable materials over a substrate, such as a silicon wafer, to protect ...

using light projected on a

photosensitive Photosensitivity is the amount to which an object reacts upon receiving photons, especially visible light. In medicine, the term is principally used for abnormal reactions of the skin, and two types are distinguished, photoallergy and phototoxicity. ...

metarial film (

photoresist A photoresist (also known simply as a resist) is a light-sensitive material used in several processes, such as photolithography and photoengraving, to form a patterned coating on a surface. This process is crucial in the electronic industry. T ...

). *

Electron beam lithography Electron-beam lithography (often abbreviated as e-beam lithography, EBL) is the practice of scanning a focused beam of electrons to draw custom shapes on a surface covered with an electron-sensitive film called a resist (exposing). The electron ...

, using a steerable electron beam. * Nanoimprinting *

Interference lithography Interference lithography (or holographic lithography) is a technique for patterning regular arrays of fine features, without the use of complex optical systems or photomasks. Basic principle The basic principle is the same as in interferometry or ...

Magnetolithography Magnetolithography (ML) is a photoresist-less and photomaskless lithography method for patterning wafer surfaces. ML based on applying a magnetic field on the substrate using paramagnetic metal masks named "magnetic mask" placed on either topside ...

Scanning probe lithography Scanning probe lithography (SPL) describes a set of nanolithographic methods to pattern material on the nanoscale using scanning probes. It is a direct-write, mask-less approach which bypasses the diffraction limit and can reach resolutions belo ...

* Surface-charge lithography *

Diffraction lithography Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a s ...

These processes differ in speed and cost, as well as in the material they can be applied to and the range of feature sizes they can produce. For instance, while the size of features achievable with photolithography is limited by the wavelength of the light used, the technique it is considerably faster and simpler than electron beam lithography, that can achieve much smaller ones.

Applications

The main application for microlithography is fabrication of integrated circuits ("electronic chips"), such as solid-state memories and

microprocessor A microprocessor is a computer processor where the data processing logic and control is included on a single integrated circuit, or a small number of integrated circuits. The microprocessor contains the arithmetic, logic, and control circu ...

s. They can also be used to create

diffraction grating In optics, a diffraction grating is an optical component with a periodic structure that diffracts light into several beams travelling in different directions (i.e., different diffraction angles). The emerging coloration is a form of structura ...

microscope calibration grids A microscope () is a laboratory equipment, laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic ...

, and other flat structures with microscopic details.

References

John N Helbert (2001), ''Handbook of VLSI Microlithography''. Elsevier Science, 1022 pages. Bruce W. Smith and Kazuaki Suzuki (2007): ''Microlithography: Science and Technology'', 2nd Edition. CRC Press, 864 pages. S. Grilli, V. Vespini, P. Ferraro (2008): "Surface-charge lithography for direct PDMS micro-patterning". ''Langmuir'', volume 24, pages 13262–13265. M. Paturzo, S. Grilli, S. Mailis, G. Coppola, M. Iodice, M. Gioffré, P. Ferraro (2008): "Flexible coherent diffraction lithography by tunable phase arrays in lithium niobate crystals". ''Optics Communications'', volume 281, pages 1950–1953. Integrated circuits Lithography (microfabrication) {{manufacturing-stub

Processes

Applications

See also

References