| 摘要 |
<p>[PROBLEMS] To provide a method for fabricating a high precision diffraction optical element capable of enhancing diffraction efficiency. [MEANS FOR SOLVING PROBLEMS] A diffraction optical element having a periodical stepwise profile is fabricated by repeating a series of processes for exposing and developing a substrate (1) coated with resist (2) through a mask to form a resist pattern and then etching the resist pattern. In the first process, a pattern having a width identical to that of the step is formed and then the width of the pattern is increased in the subsequent processes. When fabricating a seven-step diffraction optical element assuming the level difference of step is D, the second, fourth and sixth step portions are etched with depth D in the first process the ninth step portion is etched with depth 2D in the second process, the fifth, sixth and seventh step portions are etched with depth 2D in the third process, and the third, fourth, fifth, sixth and seventh step portions are etched with depth 2D in the fourth process.</p> |
