Photolithography

The photolithography process draws similarities with the processes associated with photography. In both processes, an image or pattern is transferred onto a substrate by exposing a thin film of material to radiation in the visible to ultra-violet range. The regions exposed to radiation undergo a chemical reaction, which is subsequently enhanced and further processed by the application of heat and the interaction with other chemicals. The pattern on this thin film of photoresist is thus "developed", which in lithography involves leaving a pattern of resist on the substrate, which may represent the direct image of the intended structure or its negative image.