Excimer Lasers for Microlithography

Microlithography is a term describing a particular branch of lithography that is applied to manufacturing of integrated circuits. It has been introduced shortly after the invention of the integrated circuit in 1958. For an overview on microlithography, see for example. Microlithography started as optical lithography, using lamps for generating the image of a mask pattern in the photoresist on a wafer. The use of excimer lasers with wavelengths shorter than that of mercury lamps for optical microlithography was proposed already in 1980 in order to keep up with the demand for advanced semiconductor chips. Since then optical lithography has been one of the main drivers for the development of excimer laser technology (c.f. section 1.3). The demands on excimer laser technology are unique for this application and will be discussed in detail in this article. Driven by the efforts for the lithography application new optical specifications and a mature, economic performance has become available and has led to the spin-off of new applications.