Experimental verification of deposition rate increase, with maintained high ionized flux fraction, by shortening the HiPIMS pulseShow others and affiliations
2021 (English)In: Plasma sources science & technology, ISSN 0963-0252, E-ISSN 1361-6595, Vol. 30, no 4, article id 045006Article in journal (Refereed) Published
Abstract [en]
High power impulse magnetron sputtering (HiPIMS) is an ionized physical vapor deposition technique, providing a high flux of metal ions to the substrate. However, one of the disadvantages for industrial use of this technique is a reduced deposition rate compared to direct current magnetron sputtering (dcMS) at equal average power. This is mainly due to a high target back-attraction probability of the metal ions with typical values in the range 70%-90% during the pulse. In order to reduce this effect, we focused on the contribution of ion fluxes available immediately after each HiPIMS pulse; a time also known as afterglow. Without a negative potential on the target at this stage of the HiPIMS process, the back-attracting electric field disappears allowing remaining ions to escape the magnetic trap and travel toward the substrate. To quantify the proposed mechanism, we studied the effect of HiPIMS pulse duration on the outward flux of film-forming species in titanium discharges, which are known to exhibit more than 50% reduction in deposition rate compared to dcMS. By shortening the HiPIMS pulse length, it was found that the contribution to the outward flux of film-forming species from the afterglow increases significantly. For example, HiPIMS discharges at a constant peak current density of about 1.10 A cm(-2) showed a 45% increase of the deposition rate, by shortening the pulse duration from 200 to 50 mu s. Ionized flux fraction measurements, using a gridless quartz crystal micro-balance-based ion meter, showed that this increase of the deposition rate could be achieved without compromising the ionized flux fraction, which remained approximately constant. The key to the achieved optimization of HiPIMS discharges lies in maintaining a high peak discharge current also for short pulse lengths to ensure sufficient ionization of the sputtered species.
Place, publisher, year, edition, pages
IOP PUBLISHING LTD , 2021. Vol. 30, no 4, article id 045006
Keywords [en]
magnetron sputtering; high-power impulse magnetron sputtering (HiPIMS); deposition rate; ionized flux fraction; pulse length
National Category
Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:liu:diva-175614DOI: 10.1088/1361-6595/abec27ISI: 000639930100001OAI: oai:DiVA.org:liu-175614DiVA, id: diva2:1553864
Note
Funding Agencies|Swedish Research CouncilSwedish Research CouncilEuropean Commission [VR 2018-04139]; SwedishGovernment Strategic Research Area in Materials Science on FunctionalMaterials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; JSPS (Japan Society for the Promotion of Science)Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of Science [17KK0136]
2021-05-112021-05-112022-09-15