| 摘要 |
PROBLEM TO BE SOLVED: To make surface roughness of reflecting surfaces of a saw-tooth diffraction grating small, to make a vertical angle acute, and also to make two sides containing the vertical angle linear. SOLUTION: A sine-wave or sine-wave half-wave type resist pattern corresponding to grating grooves is formed on a substrate 10 by a holographic exposure method, and then the substrate 10 and resist 21 are etched until the resist reaches an approximately 1/3 height through a 1st etching stage of irradiating them with an ion beam obliquely at the same angle as a blaze angle while using CF<SB>4</SB>as etching gas. Further, the substrate 10 is etched into a slightly over-etched state wherein the resist is completely removed through a 2nd etching stage of irradiating them with an ion beam in the same direction with the bisector of the vertical angle while using mixed gas of CF<SB>4</SB>and O<SB>2</SB>as etching gas. Consequently, the surface roughness of the resist decreases and is reflected on grating grooves of the substrate to reduce influence of irregularity of height of the resist, and further a carbon rich state in etching is eliminated to prevent surface roughening due to the carbon rich state. COPYRIGHT: (C)2005,JPO&NCIPI
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