| abstract |
The disclosure relates to a method for making a grating. The method includes the following steps. First, a substrate is provided. Second, a patterned mask layer is formed on a surface of the substrate. Third, the substrate with the patterned mask layer is placed in a microwave plasma system. Fourth, a plurality of etching gases are guided into the microwave plasma system simultaneously to etch the substrate through three stages. The etching gas includes carbon tetrafluoride (CF 4 ), argon (Ar 2 ), and sulfur hexafluoride (SF 6 ). Finally, the patterned mask layer is removed. |