Echelle diffraction grating, excimer laser, manufacturing method of echelle diffraction grating, and ArF excimer laser

摘要

An Echelle diffraction grating (1) has a Littrow configuration. Each grating includes a resin layer (11) made of light curing resin and having a thickness between 2 µm and 10 µm, and a reflective coating layer (12) formed on the resin layer, having a thickness between 120 nm and 500 nm, and made of aluminum. An apex angle (6) between a blazed surface (3) and a counter surface (8) is between 85° and 90°. A first blaze angle is an angle that maximizes diffraction efficiency of a set blazed order for incident light of a wavelength of 193.3 nm. A blaze angle (5) has an initial value of a second blaze angle smaller than the first blaze angle. 0.25°‰¤bd-ba‰¤1.2° is satisfied where bd denotes the first blaze angle and ba denotes the second blaze angle.