Apparatus for depositing a thin layer of sputtered atoms on a member

Abstract

A target releases electrons to an anode through a cavity containing gaseous atoms (e.g. argon) having properties of becoming ionized by electron impingement. Magnetic and electrical fields increase the distance of electron travel between the anode and the target, thereby enhancing ion formation from the gaseous atoms. The ions bombard the target and cause it to emit sputtered atoms (e.g. aluminum) which are deposited on a substrate (e.g. wafer) displaced from the target. In one embodiment, a shield disposed between the target and the substrate is shaped, and has a potential, to attract charged particles and prevent them from moving to the substrate. This allows the wafer to be disposed close to the target, thereby enhancing the density, and the thickness uniformity, of the deposition on the substrate. The shield also acts as a getter to remove impurities (e.g. water molecules) from the space between the target and the substrate. In another embodiment the shield has a positive potential to attract electrons and repel ions, thereby funneling ions toward the substrate. The funnel shape is dependent upon the shield voltage. A hood displaced slightly (e.g. 50 mils) from the shield is shaped, and has a potential (e.g. ground), to attract charged particles near the hood and outside of the funnel. The funneled ions and sputtered atoms are deposited on the substrate to generate heat in the substrate, thereby enhancing the properties of the substrate deposition. Sputtered atoms between the shield and the hood form a dielectric to prevent any voltage breakdown between the shield and the hood.