Comment by kragen
Intel's wafers are made of silicon, which is a semiconductor. Silicon on sapphire hasn't been widely used for a long time, if that's what you're thinking of. Photolithography prints resists on semiconductor wafers which are then used to pattern the next process step, such as wet etching, plasma etching, oxide growth, epitaxial polysilicon growth, ion implantation, etc. These mostly remove semiconductor from the wafer or alter its properties.
Interesting, I hadn't known that silicon is itself a semiconductor before all the circuits are added. Am I correct in saying that the etching process transforms a single semiconductor into billions?