A principal limitation for densely packed, submicrometer very large scale integrated circuits is reproducible registration accuracy. The resist covering the alignment targets is a major contributor to poor and nonreproducible alignment signals. Further, the availability of new imaging materials (contrast enhancing materials and multilayer resists systems) allows for submicrometer production resolution, but with the limitation that the alignment signal may be further degraded. This study presents data on registration improvement resulting from the removal of patterning material covering alignment targets. The patterning materials were removed by photoablation using an excimer laser system operating at 193 nm. The removal involves the illumination of the target area with 10–12 laser pulses of ∼17‐ns duration. During the illumination the contrast enhancing material and resist disintegrate into largely molecular fragments that are scavenged by an air‐bearing nozzle. Electrical probe measurements of polysilico...
