Open AccessTime-resolved optical emission spectroscopy of a unipolar and a bipolar pulsed magnetron sputtering discharge in an argon/oxygen gas mixture with a cobalt target
Author(s) -
R. Hippler,
Martin Čada,
Vítězslav Straňák,
Zdeněk Hubička
Publication year - 2019
Publication title -
plasma sources science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 108
eISSN - 1361-6595
pISSN - 0963-0252
DOI - 10.1088/1361-6595/ab54e8
Subject(s) - high power impulse magnetron sputtering , argon , atomic physics , sputtering , ion , analytical chemistry (journal) , excited state , plasma , sputter deposition , chemistry , ionization , spectroscopy , materials science , thin film , nanotechnology , physics , organic chemistry , chromatography , quantum mechanics
Reactive high power impulse magnetron sputtering (HiPIMS) of a cobalt cathode in pure argon gas and with different oxygen admixtures was investigated by time-resolved optical emission spectroscopy (OES) and time-integrated energy-resolved mass spectrometry. The HiPIMS discharge was operated with a bipolar pulsed power supply capable of providing a large negative voltage with a typical pulse width of 100 μ s followed by a long positive pulse with a pulse width of about 350 μ s. The HiPIMS plasma in pure argon is dominated by Co + ions. With the addition of oxygen, O + ions become the second most prominent positive ion species. OES reveals the presence of Ar I, Co I, O I, and Ar II emission lines. The transition from an Ar + to a Co + ion sputtering discharge is inferred from time-resolved OES. The enhanced intensity of excited Ar +* ions is explained by simultaneous excitation and ionisation induced by energetic secondary electrons from the cathode. The intensity of violet Ar I lines is drastically reduced during HiPIMS. Intensity of near-infrared Ar I lines resumes during the positive pulse indicating an additional heating mechanism.