Development of molding process to reproduce micro-structures of 100 nm pitch at a wide area of 100 mm - side square

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The purpose of this research is to develop a new molding process to reproduce micro-structures of 100nm pitch on a wide area of 100mm-side square for a new optical element. To realize the purpose, the research executed the three projects : (a)locally controlling the molding process, (b)precisely fabricating the micro-structures on the mold surface, and (c)prototyping the optical element. (a)The surface temperature and heat flux on the mold surface and the pressure of the reproduced material in a cavity ware controlled in the molding process like injection molding or hot pressing. In result, we revealed that the micro-structures could be reproduced when the surface temperature should be hold at the glass transformed temperature (Tg)and more during only one second just after the first contact between the mold and the reproduced material, while the pressure of the reproduced material might be low even at several MPa. (b)The micro-structures were fabricated using electron beam lithography and fast atom beam (FAB)etching on the SiC material of a ceramics mold for glass hot pressing, and focus ion beam (FIB)curving on the Ni plated material of a metal mold for plastic injection molding or hot pressing. The idle square groove, however, was made as a trapezoid groove on the ceramics mold after FAB etching, or a round bottom groove on the metal mold after FIB curving. (c)The optical elements like a line ＆ space grating were prototyped : a polarized plate with metal lines on the groove, or a color filter where only special lights are transparent because the each pitch is designed for the special light. They could realize the optical performance as simulated using the Maxwell equation.