Patent ID: 7339652
Filing Date: 2008-03-04
Classification: G03F

Abstract:
1. An apparatus for projecting a pattern into an image plane, comprising: a radiation source arranged along an optical axis and configured to project radiation toward the image plane; a mask arranged in a mask plane along the optical axis, wherein the pattern to be projected into the image plane is formed on the mask, and wherein the mask comprises a first region including an alternating phase shift mask and a second region including an attenuated phase shift mask or a chromium mask; and an illumination pupil configured to produce a quadrupole illumination for projection onto the mask, the illumination pupil including at least four bright zones spaced apart from the optical axis such that the second region is projected into the image plane with a selected depth of field range, wherein at least two of the bright zones are elongated such that the first region is projected into the image plane with a selected contrast.