A photomask is a glass plate with pattern (i.g. electric circuits) chrome etched on a side. The chrome is applied only on one side of the glass plate. Anti-dust protection cover called pellicle is applied if required. In most of the cases, the chrome is double layered with pure chrome and chrome oxide that prevents the light reflection.
![Photomask structure](/en/product/image/pr_img02.jpg)
Photomask patterns are created with chrome on the designated area. Laser beam exposure is applied according to the design data on a glass substrate covered with chrome and photoresist layers. Then, it goes through development and etching steps to complete the patterning. NIPPON FILCON is using positive-type photoresist, thus the laser-beamed area shall be removed during the development process. The area shall be etched and appears as a clear area.
![Step1 Exposure](/en/product/image/pr_img03.jpg)
Based on the design data, apply laser beam to the designated area for the photo resist to be exposed.
![↓](/en/product/image/pr_img04.jpg)
![Step2 Development](/en/product/image/pr_img05.jpg)
For positive type photo resist, by being exposed to the light, the photo resist coating of the exposed area is removed by the exposure process.
![↓](/en/product/image/pr_img04.jpg)
![Step3 Etching](/en/product/image/pr_img06.jpg)
Chrome area on the revealed surface is removed by etching.
![↓](/en/product/image/pr_img04.jpg)
![Step4 Removing photo resist](/en/product/image/pr_img07.jpg)
Remove the remaining photo resist on the chrome. After rinsing, the photomask pattern is completed.