3.3. Photoresist
As the key of photolithography, photoresist refers to thin film materials whose solubility and adhesion change significantly after exposure by light sources, then the micro-patterns can be obtained through development, etching and other processes.[97] It is widely employed in the fields of printed circuit boards (PCB),[98-100] display device,[101-103] integrated circuit,[104] and other fine graphics processing. Photoresist can be divided into positive photoresist and negative photoresist on the basis of the area retained after development, in which negative photoresist is photocurable materials. The schematic diagram of photolithography is shown in Figure 27.[97]