High-energy ions and atoms sputtered and reflected from a magnetron source for deposition of magnetic thin films

In the magnetron sputtering process, moderate bombardment of particles on a substrate gives favorable effects on the deposited films, while excessive bombardment at high energies may cause film damage and surface roughness. To make these influences clear, high-energy ions and neutrals are comprehensively measured by a mass spectrometer with an energy analyzer in the case of magnetron sputtering of a Permalloy(TM) target (80% Ni/20% Fe). Ni atoms sputtered from the target by a dc magnetron discharge (similar to 600 V, < 0.2 A) in argon below 4 Pa have an energy distribution function (EDF) spreading no to similar to 8 eV. A similar shape of EDF is also observed for Ni+ ions, which are produced possibly by electron-impact ionization of Ni atoms in gas phase. The EDF of At+ ions has a tail of extremely high energies of similar to 150 eV. Production of such energetic ions is tentatively explained in terms of resonant charge exchange of energetic Ar atoms reflected from the target after surface neutralization of similar to 600 eV Ar+ ions impinging on the target. The existence of energetic Ar atoms is verified by mass spectrometry with an extra-ionizer, and is also supported by a sputtering simulation code (TRIM). (c) 2005 American Vacuum Society.