photolithography

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photolithography

Electronics a process used in the manufacture of semiconductor devices, thin-film circuits, optical devices, and printed circuits in which a particular pattern is transferred from a photograph onto a substrate, producing a pattern that acts as a mask during an etching or diffusion process

Photolithography

 

(1) A special photographic process that uses high-resolution photoresists. The purpose of the process is to produce an aperture, or window, of a given configuration in the layer of a photoresist in order to permit access of an etching agent to a semiconductor plate coated with an oxide film and situated beneath the photoresist layer. The windows are formed upon exposure of the photoresist to ultraviolet radiation or an electron beam, as a result of which negative photoresists become insoluble and positive photoresists become soluble. One of the many uses of photolithography is to produce an ordered arrangement of hundreds of thousands of tiny holes in the aperture masks used in color television kinescopes.

(2) A photomechanical method for the production of a lithographic printing plate, in which the image from a negative is copied onto a light-sensitive film covering the surface of a lithographic stone or metal sheet. After developing, the copy is subjected to a chemical treatment that divides the surface into printing and blank spaces. Photolithography has been used only rarely in the 20th century.

photolithography

[¦fōd·ō·li′thäg·rə·fē]
(graphic arts)
Lithography in which photographically produced plates or masks are used.

photolithography

A lithographic technique used to transfer the design of circuit paths onto printed circuit boards as well as the circuit paths and electronic elements of a chip onto a wafer's surface.

A photomask is created with the design for each layer of the board or wafer (chip). The board or wafer is coated with a light-sensitive film (photoresist) that is hardened when exposed to light shining through the photomask. The board or wafer is then exposed to an acid bath (wet processing) or hot ions (dry processing), and the unhardened areas are etched away. See chip and printed circuit board.