EFFECT OF LENS ABERRATION ON RESIST PATTERN PROFILES IN EDGE-LINE PHASE-SHIFT METHOD

In edge-line phase-shift lithography, asymmetrical resist patterns for med by both sides of shifter edges have been observed in the case of a narrow shifter. The effect of phase error, shifter width and shifter edge angle on resist pattern profiles has been investigated by simulat ions and experiments. It has been confirmed that the asymmetry of resi st patterns is mainly due to the coma aberration of the stepper projec tion lens and is enhanced as the shifter width becomes narrower. The e ffect of decreasing the shifter edge angle has proved to be equivalent to the effect of narrowing the effective shifter width.