The core process is similar to darkroom photography.
What is photolithography?
Photolithography refers to techniques or processes that use light to produce patterned thin films over a substrate. The pattern made in the photoresist is created by exposing it to light either through projection through a lens or illuminating a mask over the substrate. This core process is similar to how darkroom photos are developed.
In short, semiconductor lithography is the process of using light to print tiny patters on silicon.
How is this done?
Light is projected through a blueprint of the pattern known as the mask or reticle. This blueprint is about 4 times larger than the intended pattern on the chip. With the pattern encoded with light, the system's optics shrink and focus the pattern onto the photosensitive wafer. Once this is finished, the system will move on to focusing the pattern on other sections of the wafer. This process is repeated until the entire top layer of the wafter is covered with the pattern.
How does this connect with Moore’s Law?
The number of transistors in a dense circuit doubles about every two years.
Gordon Moore, the cofounder of Intel made this prediction. So, far it has been true. It has sort of become a self-fulfilling prophecy as this has been set as the target for long-term planning and research and development.
A latest innovation within the semiconductor industry is EUV or extreme ultraviolet lithography which has reduced the wavelength of the light used from 193nm to 13.5nm. This allows for smaller transistors and smaller semiconductors to be able to accomplish the same tasks.