Development of Photolithography for Semiconductor Manufacturing – A Review

We review the development of photolithography for semiconductor manufacturing from early 1960s to the present. From the 1960s to early 1970s, contact and proximity printing were the only methods used in manufacturing, achieving a minimum critical dimension of about 4 μm. Projection lithography was adopted in manufacturing with the advent of Perkin-Elmer’s unit-magnification wafer scanners in the 1970s, and was advanced with the arrival of wafer steppers from GCA, Canon, Nikon, ASML, and others, employing mercury (Hg) arc lamps as the light source. These Hg g-line (436 nm in wavelength) machines provided about 0.8-μm practical resolution in the fab. Wafer steppers using the Hg i-line (365 nm in wavelength) came to wide use starting about 1990. Combined with off-axis illumination, i-line lithography was able to reach below 0.35 μm in resolution. Deep ultraviolet lithography using the KrF excimer laser (248 nm in wavelength) came next, entering into production at about 1997 for the 0.25-μm logic node (with a minimum half-pitch of 0.25 μm), followed by the adoption of ArF-excimer-laser lithography (193 nm in wavelength), whose initial use in manufacturing, for the 0.13-?m node of logic integrated circuits, took place in 2001. Massive transition to 193-nm lithography happened in the 90-nm node. 193-nm lithography employing water immersion entered production at Taiwan Semiconductor Manufacturing Company (TSMC) in 2007 at the 40-nm node and enabled continued geometrical scaling for more than a decade with multiple-patterning techniques. Extreme ultraviolet (EUV) lithography entered into manufacturing in 2019 and printed dense lines of 20-nm half-pitch that year. With the arrival of the 0.55 NA EUV scanner in 2024, dense lines of less than 10-nm half-pitch can now be printed. In the course of sixty-five years, photolithography achieved a greater than 400X reduction in linear dimension and enabled a 2×105 increase in areal density.