Optical Lithography - Key Enabling Technology for our Modern World

In 1959, Richard P. Feynman initiated the Nano-age in his lecture “There’s plenty of room at the bottom”. Feynman also had a clear vision about computers and asked: ”Why can’t we make them very small, make them of little wires, little elements - and by little, I mean little. For instance, the wires should be 10 or 100 atoms in diameter, and the circuits should be a few thousand angstroms across.” At the same time, Jean Hoerni from Fairchild Semiconductors tried to get his “planar process” to production. Hoerni’s planar process using silicon substrates, so-called “wafers”, revolutionized semiconductor manufacturing and was widely adapted by the industry. The great success of the planar wafer process is also much related with tremendous improvements in optical lithography over all the years. From the early age dominated by mask aligners to highly sophisticated steppers and scanners, lithography was the key enabling technology, allowing now – 50 years after Feynman’s vision – nanostructuring down to the atomic scale on 300mm planar wafers. The evolutionary development of optical lithography is reviewed along with a brief discussion of options for the future.