Based in the Veldhoven, Netherlands, ASML Holding N.V. (ASML) is the world's largest original equipment manufacturer (OEM) of advanced photolithography systems used within the semiconductor manufacturing industry to produce integrated circuits (ICs). Gartner Dataquest, an industry consultant, estimated that ASML had 51% share of the market in 2004. Photolithography systems are employed during the front-end process of semiconductor production.
The front-end process begins with device formation. This process begins with a wafer (usually made of silicon) having a layer of photoresist (a chemical that hardens when exposed to an ultraviolet light source) spin-coated onto the surface in liquid form to drive off the excess solvent, and then "soft-baked" or cured. A photomask is then loaded into the lithography system. Photomasks, also called masks or reticles (if the mask is "stepped" across the wafer), are high-purity quartz or glass plates containing precise microscopic images that are used by a photolithography tool, also known as a stepper. An excimer laser is then passed over the photomask and through a reduction lens system that exposes the desired areas of photoresist, which is then subsequently removed, permitting deposition to the surface of the wafer. A strip system is utilized to remove the photoresist or other chemical residues following diffusion processing or film deposition. Thin layers of dopants are then grown or deposited in a precise pattern within the wafer using various chemical, vapor or ion implant techniques. The deposition process alters the atomic structure of the material, and therefore necessarily the electronic properties of the material. Further into the wafer fabrication process, a series of metallization steps are executed, in which conducting materials, that interconnect the semiconductor devices, are deposited. Multiple layers of conducting, semiconducting and insulating materials are constructed on and within the wafer via successive steps of lithography, etching and deposition, utilizing unique masks for each layer. Depending on the geometry and the device, anywhere from 35 to 45 unique masks are used in the device formation process with 10 to 100 layers (or more for microprocessors) being constructed. Typically, the outcome is a wafer with multi-layered semiconducting devices, known as transistors. The transistors are interconnected with conducting materials, and insulating materials are used to electronically isolate the active components. The net result is a silicon wafer that contains multiple copies of integrated circuit devices.(Read more at Wikinvest )