Thin film contact resistance with dissimilar materials

This paper presents results of thin film contact resistance with dissimilar materials. The model assumes arbitrary resistivity ratios and aspect ratios between contact members, for both Cartesian and cylindrical geometries. It is found that the contact resistance is insensitive to the resistivity ratio for a/h < 1, but is rather sensitive to the resistivity ratio for a/h > 1 where a is the constriction size and h is film thickness. Various limiting cases are studied and validated with known results. Accurate analytical scaling laws are constructed for the contact resistance over a large range of aspect ratios and resistivity ratios. Typically the minimum contact resistance is realized with a/h ∼ 1, for both Cartesian and cylindrical cases. Electric field patterns are presented, showing the crowding of the field lines in the contact region.