Impact of Random Dopant Fluctuation on Size-Dependence of Contact Resistance

Reducing the size of semiconductor devices causes contact in deca-nano size. Substantial fluctuation of contact resistance is anticipated owing to the reduction of impurity atoms in the contact holes. In this study, the impact of the random dopant fluctuation on the contact resistance is revealed by three-dimensional device simulation with a Schottky contact model. The standard deviation of the contact resistance could become 50%, dominated by the number of impurity atoms in the depletion layer formed by the Schottky barrier. The average value of the contact resistance could increase as the impurity concentration decreases because of the reduction of the tunneling path.