| 摘要 |
PURPOSE:To prevent the change of resist in properties so as to manufacture an excellent lambda/4 shift type diffraction grating by a method wherein a process in which an insulating film is formed on the resist is dispensed with. CONSTITUTION:A diffraction grating is formed of an insulating film 2 of SiNx on a substrate 1, a first resist 3 is applied onto the substrate 1 where the diffraction grating has been formed, and a part of the resist 3 is separated from the surface so as to expose a part of the surface of the diffraction grating of the insulating film 2. Then, a part of the diffraction grating whose length is nearly half that of the substrate 1 in a longitudinal direction of a resonator is removed, and then the substrate 1 is etched using the pattern of the resist 3 left unremoved in direct contact with the part where the diffraction grating has been removed. Then, the substrate 1 is etched using the pattern of the diffraction grating of the insulating film 2 on the rest part of the substrate 1 to form the diffraction grating. Therefore, a process, in which an insulating film is formed, is dispensed with. By this setup, resist is protected against degradation in properties and an excellent lambda/4 shift type diffraction grating can be manufactured.
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