Formation of metal silicide-silicon contact with ultralow contact resistance by silicon-capping silicidation technique

Abstract

Ultralow contact resistance of metal silicide-n+-Si contact has been achieved by a novel contact metallization process employing Ta silicidation of a n+-Si contact surface by a Si-capping silicidation technique. The Si-capping silicidation has been employed to realize an ultraclean silicidation. The as-deposited Ta surface is in situ covered with a very thin Si protection layer in order to prevent the metal surface from being oxidized or contaminated. By combining the oxide-layer-free Si/metal on Si deposition process and an ultraclean ion implantation for mixing, metal silicide-n+Si structure has been formed by low temperature thermal annealing in an ultraclean Ar gas. As a result, an ultralow contact resistivity of 5.8×10−9 (Ω cm2) has been achieved.