Photolithography is the most complicated part of the manufacturing process. Here, the lithographic tools print smaller and smaller geometric patterns to form the memory cells. The machinery operates in yellow light to avoid any unwanted exposure of the wafers. Inside the photolithography area, wafers transported via a FOUP pass through a photoresistant coating operation, then receive patterning, and finally undergo a development cycle in which equipment transfers the pattern to the wafer surface. Subsequent processing etches the pattern into the silicon wafer.