Light-absorbing antireflective layers with improved performance due to refractive index optimization

Abstract

The invention consists of a light absorbing top antireflective layer that reduces the swing curve amplitude for photoresist materials used in the semiconductor industry. The coating may be water based but is not necessarily so. The advantage of a water-based coating is its ease of use, since it can be applied without intermixing to the softbaked photoresist, and is removed in the development step, so that process complexity is only minimally increased. One problem that has been associated with the existing non-absorbing antireflective coatings is that the optimum swing curve reduction is only achieved at a very low refractive index. The advantages of a dyed coating are a) that the refractive index of the top coat can additionally be lowered by making use of anomalous dispersion effects if the dye is chosen judiciously, and b) that it is possible to achieve the optimum swing curve reduction at a higher refractive index of the top coat. By a combination of these two effects, the present invention demonstrates a reduction of the swing curve close to the theoretical minimum value, which constitutes a substantial improvement over existing antireflective topcoats.

Dependencies are inferred from the claim text.