Vertical synchrotron radiation beamline for proximity X-ray lithography: Theoretical analysis

The general physical principles of operation of the vertical beamline of synchrotron radiation (SR) intended for proximity X-ray lithography are considered. An optical system provides a deflection of the SR beam to the vertical plane, a cutoff of the hard X-rays, a uniform illumination of a wafer, a normal incidence of X-ray beam onto a mask, and a small enough divergency of the radiation. A vertical SR beamline makes it possible to circumvent the expensive development of vertical-plane displacement steppers and to use the conventional horizontal ones, to exclude the scanning of the SR beam across the mask and to reduce the requirements imposed on the accuracy of alignment of a gap between the mask and the wafer.