SiNx Coatings Deposited by Reactive High Power Impulse Magnetron Sputtering: Process Parameters Influencing the Nitrogen Content
2016 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 31, 20386-20396 p.Article in journal (Refereed) Published
Reactive high power impulse magnetron sputtering (rHi-PIMS) was used to deposit silicon nitride (SiNx) coatings for biomedical applications. The SiNx growth and plasma characterization were conducted in an industrial coater, using Si targets and N-2 as reactive gas. The effects of different N-2-to-Ar flow ratios between 0 and 0.3, pulse frequencies, target power settings, and substrate temperatures on the discharge and the N content of SiNx coatings were investigated. Plasma ion mass spectrometry shows high amounts of ionized isotopes during the initial part of the pulse for discharges with low N-2-to-Ar flow ratios of amp;lt;0.16, while signals from ionized molecules rise with the N-2-to-Ar flow ratio at the pulse end and during pulse off times. Langmuir probe measurements show electron temperatures of 2-3 eV for nonreactive discharges and 5.0-6.6 eV for discharges in transition mode. The SiNx coatings were characterized with respect to their composition, chemical bond structure, density, and mechanical properties by X-ray photoelectron spectroscopy, X-ray reflectivity, X-ray diffraction, and nanoindentation, respectively. The SiNx deposition processes and coating properties are mainly influenced by the Nz-to-Ar flow ratio and thus by the N content in the SiNx films and to a lower extent by the HiPIMS frequencies and power settings as well as substrate temperatures. Increasing N2-to-Ar flow ratios lead to decreasing growth rates, while the N content, coating densities, residual stresses, and the hardness increase. These experimental findings were corroborated by density functional theory calculations of precursor species present during rHiPIMS.
Place, publisher, year, edition, pages
AMER CHEMICAL SOC , 2016. Vol. 8, no 31, 20386-20396 p.
SiNx; HiPIMS; positive ion plasma mass spectrometry; Langmuir probe measurements; residual film stress; XPS
Manufacturing, Surface and Joining Technology
IdentifiersURN: urn:nbn:se:liu:diva-131907DOI: 10.1021/acsami.6b05830ISI: 000381331600063PubMedID: 27414283OAI: oai:DiVA.org:liu-131907DiVA: diva2:1034862
Funding Agencies|European Union [GA-310477]; Carl Trygger Foundation for Scientific Research [CTS 14:431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (SFO-Mat-LiU) [2009-00971]2016-10-132016-10-112016-10-13