Suppressed silicide formation in FePt thin films by nitrogen addition

Abstract

FePt and FePtN thin films have been prepared on silicon substrates by the relatively new deposition technique known as High Target Utilisation Sputtering. Films were annealed postdeposition at temperatures up to 8000C in order to induce the high-anisotropy L10 phase. The FePt films initially showed an improvement in magnetic properties with annealing temperature, but for annealing above around 400 •C the magnetic properties deteriorated markedly. The magnetic properties of the FePtN films, however, continued to improve with increasing annealing temperature, right up to the maximum temperature applied of 800 •C. Analysis by x-ray diffraction revealed the formation of iron and platinum silicides in FePt films above 400 •C, but that such silicides are absent from the FePtN at all annealing temperatures except 800 •C. This behaviour is attributed to the nitrogen in FePtN films reacting preferentially with the silicon in the substrate to form silicon nitride, thus suppressing the formation of platinum and iron silicides. Thus, by introducing nitrogen during the deposition of FePt films on Si substrates th formation of deleterious silicides appears to be suppressed during thermal treatment, thereby offering protection against silicon pollution. • C in order to induce the high-anisotropy L1 0 phase. The FePt films initially showed an improvement in magnetic properties with annealing temperature, but for annealing above around 400• C the magnetic properties deteriorated markedly. The magnetic properties of the FePtN films, however, continued to improve with increasing annealing temperature, right up to the maximum temperature applied of 800• C. Analysis by x-ray diffraction revealed the formation of iron and platinum silicides in FePt films above 400• C, but that such silicides are absent from the FePtN at all annealing temperatures except 800• C. This behaviour is attributed to the nitrogen in FePtN films reacting preferentially with the silicon in the substrate to form silicon nitride, thus suppressing the formation of platinum and iron silicides. Thus, by introducing nitrogen during the deposition of FePt films on Si substrates the formation of deleterious silicides appears to be suppressed during thermal treatment, thereby offering protection against silicon pollution.

Silicide induced surface defects in FePt nanoparticle fcc-to-fct thermally activated phase transition

“…Promising ways to address both sintering and alloy formation could rely on the design of buffer layers between the FePt nPs and the silica shell. These could include magnesium oxide, carbon or even FePtN buffer shells or matrix [24,25,92]. Alternatively, low temperature and high pressure approaches might be appropriate to convert superparamagnetic nPs selforganised on a substrate into a ferromagnetic nP thin film [93].…”

Influence of an Atmosphere of Annealing on Magnetic Properties of Nanosize Films of FePt Alloy

“…Реґулювальний вплив на кінетику впорядкування здійснюють механічні напруження розтягу [7], які можна створювати або введенням до складу плівкових композицій проміжних додаткових шарів [8,9], або варіюванням параметрів термічного оброблення, зокрема, складу її атмосфери. Наприклад, відпал в атмосфері азоту сприяє його проникненню в ґратницю FePt та пришвидшенню дифузійної рухливости атомів Fe та Pt і, тим самим, пришвидшує процес впорядкування [10][11][12]. Аналогічний ефект спостерігається у водневмісному середовищі відпалу [13][14][15].…”

Exploring the potential of remote plasma sputtering for the production of L10ordered FePt thin films

“…The only significant work on remote plasma sputtering of FePt was reported by Tran & Wright [24] who observed the formation of Fe and Pt silicides when annealing FePt thin films deposited on Si substrates at high temperatures. Here we explore the potential of remote plasma sputtering to create L1 0 ordered FePt thin films with modified properties.…”