Patent ID: 9423697
Filing Date: 2016-08-23
CPC Classification: G02B,G03F

Claim Text:
1. An illumination optical apparatus which illuminates a pattern on a mask with illumination light, the illumination optical apparatus comprising: an optical integrator arranged in an optical path of the illumination light on an incidence side of a pupil plane of the illumination optical apparatus; and a birefringent member made of a birefringent material, which is arranged in the optical path on an incidence side of the optical integrator, and which changes a polarization state of the illumination light so that the illumination light from the birefringent member is irradiated onto the pattern through the pupil plane in a polarization state in which a principal component is S-polarized light, wherein a first thickness of the birefringent member in an optical path of a first light of the illumination light is different from a second thickness of the birefringent member in an optical path of a second light of the illumination light so that a polarization direction of the first light and a polarization direction of the second light are different from each other on the pupil plane, the first light and the second light being incident on the birefringent member in a polarization state having a substantially same polarization direction, and the first light passes through a first position on the pupil plane and the second light passes through a second position on the pupil plane, the first position and the second position being different from each other and being away from the optical axis.