Understanding Photolithography: The Heart of Modern Semiconductor Manufacturing
Photolithography is a critical microfabrication process used to pattern intricate circuit designs onto semiconductor wafers, forming the foundation of modern electronic devices. It combines principles of optics, chemistry, and engineering to transfer geometric patterns from a photomask onto a light-sensitive photoresist layer coated on a silicon wafer.
The process begins by coating the wafer with photoresist, which reacts to ultraviolet (UV) light. A photomask—containing the desired circuit pattern—is then placed over the wafer, and UV light is projected through it. The exposed areas of the photoresist either harden (in the case of a positive resist) or dissolve (in a negative resist), allowing selective etching of the underlying material. This precise patterning step is repeated multiple times to build complex microelectronic circuits layer by layer.