Effect of the local charging on the dielectric materials etching rate

Summary form only given. In this communication we present a totally new point of view on the physical phenomena underlying the reduction of the etching rate when the feature size decreases. We performed the two-dimensional simulation of the local trench charging resulting from the dry etching of a dielectric material. The Monte Carlo procedure was employed in which the particle trajectories were calculated in a self-consistent electric field. A somewhat similar attempt was made by Arnold et al. (1991), but their results seemed to have several inconsistencies and were not interpreted correctly. Our results show that the local charging effect has dramatic influence on the etching process. The resulting electric field can cause insulator damage as well as etching rate reduction because of the ion energy decrease. Based on our results we can draw a conclusion that the etch rate depends not only on the aspect ratio of the feature, but also on the feature size itself. This is in contradiction with the generally accepted viewpoint that the aspect ratio is the self-sufficient trench parameter to predict the etching rate. These results can be directly applied to the SiO/sub 2/ etching which is a very important process in integrated circuits fabrication. The predictions made on the basis of the local charging theory are in a very good agreement with the experimental data of the SiO/sub 2/ etching.