Velocity distribution of neutral species during magnetron sputtering by Fabry–Perot interferometry

The velocity distribution of a metallic neutral species sputtered in a dc magnetron discharge was measured using a planar Fabry–Perot interferometer and a hollow cathode lamp as a reference source. The measurement was performed under different angles of view relative to the target surface. The velocity distribution function in the direction perpendicular to the target becomes asymmetrical as the Ar pressure decreases, whereas it remains nearly symmetrical when the line of sight is parallel to the target surface. The average velocity of the sputtered Ti atoms was measured to be about 2km∕s.