the root words photo, litho, and graphy all have Greek origins, with the meanings ‘light’, ‘stone’ and ‘writing’ respectively
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 selected areas of it during subsequent etching, deposition, or implantation operations.
typically, ultraviolet light is used to transfer a geometric design from an optical mask to a light-sensitive chemical (photoresist) coated on the substrate. The photoresist either breaks down or hardens when it is exposed to light. The patterned film is then created by removing the softer parts of the coating with appropriate solvents. Conventional photoresists typically consist of three components: resin, sensitizer, and solvent
photolithography processes can be classified according to the type of light used, such as ultraviolet, deep ultraviolet, extreme ultraviolet, or X-ray. The wavelength of light used determines the minimum feature size that can be formed in the photoresist
photolithography is a subclass of microlithography, the general term for processes that generate patterned thin films