Constriction current behavior of oxide film effect observed by using LED wafer

In order to clarify the theory of contact resistance, there are many reports in these years. Mathematically the constriction current is derived from Laplace equation at one contact which shape is circle, ellipse, triangle and square. And numerical approach for constriction current analysis was also preformed by Minowa and Sawada. Although there are many reports on the contact resistance measurement, not many reports on the detailed behavior of current density distribution in the contact area experimentally. Therefore, we attempted to observe the behavior of the current density distribution in the contact by using semiconductor wafers. As a result, it was confirmed that electric current is uniformly distributed over the contact area covered by an oxide film, while it is concentrated at the periphery of the contact if there is no oxide film at contact. And the contact resistance of apparent contact area is almost same as real contact area which is also agree with the theory of multi-spot contact. Moreover, the contact resistance is influenced by wafer thickness.