Editing Photomask (section)

{{Short description|Photolithographic tool}}
[[File:Semiconductor photomask.jpg|thumb|300px|right|A photomask. This photomask has 20 copies, also called layers, of the same circuit pattern or design.]]
[[Image:Mask illustration.svg|right|thumb|A schematic illustration of a photomask (top) and an IC layer printed using it (bottom)]]
A '''photomask''' (also simply called a '''mask''') is an opaque plate with transparent areas that allow light to shine through in a defined pattern. Photomasks are commonly used in [[photolithography]] for the production of [[Integrated circuit|integrated circuits]] (ICs or "chips") to produce a pattern on a thin [[Wafer (electronics)|wafer]] of material (usually [[silicon]]). In semiconductor manufacturing, a mask is sometimes called a '''reticle'''.<ref>{{Cite web |title=Reticle Manufacturing |url=https://www.kla.com/products/reticle-manufacturing |access-date=2024-01-05 |website=KLA |language=en}}</ref><ref>{{Cite journal |last1=Diaz |first1=S.L.M. |last2=Fowler |first2=J.W. |last3=Pfund |first3=M.E. |last4=Mackulak |first4=G.T. |last5=Hickie |first5=M. |date=November 2005 |title=Evaluating the Impacts of Reticle Requirements in Semiconductor Wafer Fabrication |url=https://ieeexplore.ieee.org/document/1528577 |journal=IEEE Transactions on Semiconductor Manufacturing |language=en |volume=18 |issue=4 |pages=622–632 |doi=10.1109/TSM.2005.858502 |s2cid=37911295 |issn=0894-6507|url-access=subscription }}</ref>

In photolithography, several masks are used in turn, each one reproducing a layer of the completed design, and together known as a '''mask set'''. A curvilinear photomask has patterns with curves, which is a departure from conventional photomasks which only have patterns that are completely vertical or horizontal, known as manhattan geometry. These photomasks require special equipment to manufacture.<ref>{{cite web | url=https://semiengineering.com/the-quest-for-curvilinear-photomasks/ | title=The Quest for Curvilinear Photomasks | date=15 April 2021 }}</ref>