| 摘要 |
In a method of producing a lambda /4-shifted diffraction grating, a positive type photoresist is applied to a substrate so that the surface level of the photoresist is in the vicinity of the node of the nodes in a standing wave light intensity distribution in the thickness direction of the photoresist that is nearest to the substrate, the light intensity distribution is produced by interference between incident light in the film and light reflected by the substrate. Then, the photoresist is subjected to two-luminous-flux interference exposure, followed by development, providing a pattern of photoresist films regions each having an over-hanging portion. Thereafter, an insulating film is deposited on the photoresist and exposed parts of the substrate, a first protective resist is selectively formed on the photoresist, the insulating film which is not covered with the first resist is removed, the substrate is etched using the photoresist, which is not covered with the first resist, as a mask, the photoresist is removed together with the first resist and the insulating film on the photoresist by lift-off, leaving the insulating film on the substrate, a second protective resist is selectively formed on the etched surface of the substrate, and the substrate is etched using the insulating film on the substrate as a mask, whereby two regions of grooves in the substrate having reversed phase are produced.
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