Lithography equipment – Step by step

From their functional principle, wafer steppers and wafer scanners can be compared to oversized slide projectors, but in this case the structures of the “slides,” i.e. the masks, are scaled down. These “exposure” or “printing” machines transmit the structures from the mask to silicon wafers that have been coated with a photoresist. This is how the pattern and design of the tracks are arranged on the semiconductor substrate. Up to 30 separate steps including coating, exposing and subsequent processing are necessary to produce the complete structure of an integrated circuit.

Lithography equipment generally consists of a radiation source, an optical beam control system for the light, an optical imaging system and photomasks. Excimer lasers with a wavelength of 248 nm are now used as radiation sources in the mass production of chips. Conversion to 193 nm with argon fluoride excimer lasers is currently underway. The next step to 157 nm with fluoride lasers has already begun at all the major producers of steppers, including the Dutch company ASML and the Japanese producers Canon and Nikon.