ANALYSIS OF HORIZONTAL-VERTICAL PATTERNING ASYMMETRY IN A LINEARLY POLARIZED DEEP UV EXPOSURE SYSTEM

The asymmetric property of horizontal and vertical lines and spaces is investigated using the commercial deep UV scanner which utilizes a po larized illumination source. An approximate aerial image threshold mod el is used to introduce the quantitative contrast value of the measure d horizontal and vertical pattern sizes. The line and space patterns a long the horizontal axis, perpendicular to the polarization direction on the mask plane, always shows a higher contrast than that of the ver tical axis. The contrast difference becomes greater as the pattern siz e becomes smaller. In addition, it is observed that the optimum exposu re energy of the-vertical line and space pattern is smaller than that of the horizontal ones. Finally, the patterning characteristics of the gate lines of the real devices with a 0.20 mu m design rule is invest igated according to the orientation of the patterns.