Sputtering apparatus

Abstract

Disclosed is a sputtering apparatus wherein the wafer-holding plate is provided with openings for accommodating wafers therein. Each opening is of a size slightly smaller than that of the wafer and is provided with a peripheral step-shaped recess so that upon mounting the wafer therein the wafer's top surface is flush with the wafer-holding plate and a major portion of its back surface thereof is exposed. Mounted in close proximity to the wafer-mounting plate is a flat heating element which directly and quickly heats the wafers via their exposed back surfaces to the desired metal silicide forming temperature. Disclosed too is a process of forming high quality metal silicide contacts by mounting the wafers covered with a contact mask on a wafer-mounting plate of a sputtering system such that the back surfaces of the wafers are exposed. After evacuating the system and establishing a positive argon pressure, sputter cleaning is accomplished to remove any native oxide formed in the wafer contact areas by applying a suitable RF potential to the wafer-mounting plate. Next, the cleaned wafers are heated by direct backside heating thereof to a desired predetermined temperature. Sputter deposition of the metal from the source on to the heated wafers and simultaneous conversion of the deposited metal into metal silicide by solid-vapor reaction between the metal vapor and the solid silicon is achieved. Alternatively, the wafer cleaning may be accomplished in a two-step process consisting of initially cleaning at room temperature followed by cleaning at a high temperature corresponding to the metal silicide forming temperature.