So what is photolithography and how does it relate to microchips?
Also called UV lithography and optical lithography, this process describes how light is used to transfer patterned coatings from a ‘reticle’ to a light sensitive ‘photoresist’ on a substrate. Chemical treatment engraves this exposure pattern onto the substrate (the substrate is the silicon wafers we have been talking about, in this case), beneath the photoresist. This can be done multiple times; indeed, some microchips (integrated circuits, to the electronics world) have up to fifty layers on them. The process is not so different from regular photography, before the age of digital cameras, when a pattern was created in the presence of light, except that our resist (the layer used to transfer a pattern to a substrate) is not a picture but an exceedingly precise circuit pattern.
Read the entire article in the Sept. 4th issue of the Express.