SIMULATION OF THE OPTICAL EFFECTS OF PARTICLES RESIDING ON TOP ANTIREFLECTIVE COATINGS FOR KRF POSITIVE PHOTORESIST FILMS

The reflection effects of particles on developed cross-sectional photo resist patterns are simulated by using a two-dimensional waveguide mod el. The particles were assumed to reside on top antireflective coating s used for chemically amplified positive photoresist films. In order t o improve the accuracy of the analysis, the exposure dose of KrF excim er laser light and focus position in the resist were optimized. The to p antireflective coating film thickness was also adjusted to the optim um thickness for obtaining the critical dimension of 0.25 mu m. Under these conditions, the light intensity distributions in the resist dept h and in the lateral direction on the focal plane are discussed, and i t is revealed that the influence of the particles is enhanced for the case of weaker light intensity. Finally, it is described that the anti reflective coating gives a wider process margin on the smallest critic al sizes of particles capable of causing pattern shorts. In conclusion , the light intensity obtained from three-dimensional Fresnel approxim ation is also taken into account. (C) 1995 American Institute of Physi cs.