| 摘要 |
PROBLEM TO BE SOLVED: To increase etching seeds contributing etching, in a method for making, on a semiconductor surface, a desired pattern having varying depth by using a first mask having a desired pattern and a second mask for controlling the amount of etching seeds diffused in an opening of the desired pattern.SOLUTION: When RIBE is performed using chlorine for etching gas, the structure of Fig.17 (b) is provided. In the etching, contribution of chlorine plasma from a SiNmask 1411 large in mask thickness is large, and contribution of chlorine plasma from a SiOmask 1410 small in mask thickness is small. Accordingly, a large quantity of the chlorine plasma without reacting on the mask diffuses into an opening at the center part of a diffraction grating large in mask width, whereby the concentration of the chlorine plasma in the opening is increased and etching speed is increased. In this case, the used mask has a two-step structure, and a lot of etching seeds are involved in etching in comparison with a single-step structure. |
