In semiconductor device fabrication, the inverse lithography technology (ILT) is an approach to photomask design. This is basically an approach to solve an inverse imaging problem: to calculate the shapes of the openings in a photomask ("source") so that the passing light produces a good approximation of the desired pattern ("target") on the illuminated material, typically a photoresist. As such, it is treated as a mathematical optimization problem of a special kind, because usually an analytical solution does not exist.[1] In conventional approaches known as the optical proximity correction (OPC) a "target" shape is augmented with carefully tuned rectangles to produce a "Manhattan shape" for the "source", as shown in the illustration. The ILT approach generates curvilinear shapes for the "source", which deliver better approximations for the "target".[2]
An illustration of a conventional optical proximity correction. The blue Γ-like shape is what chip designers would like printed on the wafer, in green is the shape after applying optical proximity correction, and the red contour is how the shape actually prints.
The ILT was proposed in 1980s, however at that time it was impractical due to the huge required computational power and complicated "source" shapes, which presented difficulties for verification (design rule checking) and manufacturing. However in late 2000s developers started reconsidering ILT due to significant increases in computational power.[1]
Referencesedit
^ abS. Chan; A. Wong; E. Lam (2008), "Initialization for robust inverse synthesis of phase-shifting masks in optical projection lithography", Optics Express, 16 (19): 14746–14760, Bibcode:2008OExpr..1614746C, doi:10.1364/OE.16.014746, PMID 18795012
inverse, lithography, semiconductor, device, fabrication, inverse, lithography, technology, approach, photomask, design, this, basically, approach, solve, inverse, imaging, problem, calculate, shapes, openings, photomask, source, that, passing, light, produces. In semiconductor device fabrication the inverse lithography technology ILT is an approach to photomask design This is basically an approach to solve an inverse imaging problem to calculate the shapes of the openings in a photomask source so that the passing light produces a good approximation of the desired pattern target on the illuminated material typically a photoresist As such it is treated as a mathematical optimization problem of a special kind because usually an analytical solution does not exist 1 In conventional approaches known as the optical proximity correction OPC a target shape is augmented with carefully tuned rectangles to produce a Manhattan shape for the source as shown in the illustration The ILT approach generates curvilinear shapes for the source which deliver better approximations for the target 2 An illustration of a conventional optical proximity correction The blue G like shape is what chip designers would like printed on the wafer in green is the shape after applying optical proximity correction and the red contour is how the shape actually prints The ILT was proposed in 1980s however at that time it was impractical due to the huge required computational power and complicated source shapes which presented difficulties for verification design rule checking and manufacturing However in late 2000s developers started reconsidering ILT due to significant increases in computational power 1 References edit a b S Chan A Wong E Lam 2008 Initialization for robust inverse synthesis of phase shifting masks in optical projection lithography Optics Express 16 19 14746 14760 Bibcode 2008OExpr 1614746C doi 10 1364 OE 16 014746 PMID 18795012 Inverse Lithography Technology ILT nbsp This technology related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Inverse lithography amp oldid 1121172992, wikipedia, wiki, book, books, library,
