SPACE FILTER USED IN DEMAGNIFICATION PROJECTION ALIGNER

摘要

PURPOSE:To provide excellent resolution and large focal point depth for a mask pattern without necessitating light wavelength reduction by permitting the phase difference between the beams that passed through the center area of a space filter and the beams that passed through the peripheral area at 180 deg.. CONSTITUTION:Large phase difference is not generated between the beams that passed through the fine lens in a fly-eye lens 18. Therefore, the phase of the beams that passed through the center area and the phase of the beams that passed through the peripheral area are shifted at 180 deg. by a phase/ transmittance modulation filter 40. Beams that passed through the space filter 40 are space-modulated into on-axis component and offaxis component by a capacitor lens 19, and these beam components are applied to a mask 20 maintaining the 180 deg. phase difference. The amplitude distribution of the two reverse phases offset the side robes and light intensity of the projecting pattern is slightly reduced. The light intensity distribution width, however, is remarkably reduced and resolution and focal point depth are improved compared with the preceding technology.