New effects of modified illumination in optical lithography

In optical lithography the most fine and isolated dark line is obtained at the phase-shifter edge of a chromeless phase-shifting mask, but only closed-loop patterns can be formed. An easy method for eliminating the useless dark line at the phase-shifter edge by combining modified illumination technologies is proposed. Using a modified light source, which is arranged along one axis (x or y) of the light source area, the resultant optical intensity is different in the x and y directions. A fine resist pattern of 0.15 μm produce along only one direction of the phase-shifter's edge is demonstrated