A wafer is exposed inside an ASML EUV lithography machine

Lithography principles

The basics of photolithography, the critical step in the chipmaking process

Microchips are made by building up complex patterns of transistors, layer by layer, on a silicon wafer. ASML’s lithography systems are central to that process.

A lithography (more formally known as ‘photolithography’) system is essentially a projection system. Light is projected through a blueprint of the pattern that will be printed (known as a ‘mask’ or ‘reticle’).

With the pattern encoded in the light, the system’s optics shrink and focus the pattern onto a photosensitive silicon wafer. After the pattern is printed, the system moves the wafer slightly and makes another copy on the wafer.

The science behind the chip