Fotorezistin

Fotorezistin is a light-sensitive material used in photolithography, a process essential for manufacturing integrated circuits and microelectromechanical systems. It is a polymer or a mixture of polymers, sensitizers, and other additives that undergoes a chemical change when exposed to specific wavelengths of light. The change in the fotorezistin's solubility in a developing solution is the key principle exploited in its use.

There are two main types of fotorezistin: positive and negative. In positive fotorezistin, the exposed areas become more soluble in the developer and are removed, leaving the unexposed areas behind. Conversely, with negative fotorezistin, the exposed areas become less soluble and remain after development, while the unexposed areas are removed.

The application of fotorezistin involves coating a substrate, such as a silicon wafer, with a thin, uniform layer. This layer is then exposed to light through a mask that contains the desired pattern. After exposure, the wafer is immersed in a developer solution, which selectively removes either the exposed or unexposed regions, thereby transferring the pattern onto the substrate. This patterned fotorezistin then acts as a protective layer during subsequent fabrication steps, such as etching or deposition. Fotorezistin plays a crucial role in achieving the high resolution and precision required for modern microfabrication.