Material damage induced by nanofabrication processes in manganite thin films

Abstract

We investigated the use of the focused ion-beam (FIB) technique as a nanofabrication tool for the implementation of oxide-based magnetic and magnetoelectronic functional devices. In particular, we studied the effect of using FIB lithography for the patterning of La(2/3)Ca(1/3)MnO(3) magnetic oxide thin films. Results obtained show that the transport properties of patterned areas were strongly degraded after the patterning process. In contrast, no degradation was detected when the patterning was performed using a less aggressive technique. The origin of this degradation correlates with Ga(+) ion implantation, as indicated by Auger spectroscopy analysis of the patterned films.

Strain‐Driven Self‐Assembled Network of Antidots in Complex Oxide Thin Films

“…However, the implementation of oxide‐based magnetoelectronic devices (e.g., magnetic tunnelling junctions, spins injectors, etc.) requires the use of expensive sophisticated and complex technology that in some cases has revealed to present serious drawbacks 4. For these reasons, the use of ordered nanostructures via spontaneous self‐organization as alternative bottom‐up nanofabrication technology has been intensively investigated in the recent years.…”

Self-assembled antidots in La2/3Sr1/3MnO3 thin films

“…Well-defined structures at nanometric scale present an increasing interest due to their unique physical properties and potential applications. Fabrication of artificial nanostructures of oxide materials requires sophisticated technology and has been recognized as a major challenge, in some cases has revealed to present serious drawbacks [4]. For these reasons, the fabrication of ordered nanostructures, via spontaneous self-organization, is a topic of major relevance, required for the most practical application [5].…”

Response to referee Adam Hitchcock

“…Both pathways are relevant in ion milling, but nuclear processes play the predominant role (Ishitani and Kaga, 1995;Prenitzer et al, 2003). Besides the sputtering of material, it is well-known that FIB milling also implants Ga + ions in a surface-near layer (Balcells et al, 2008;Cairney et al, 2000;Prenitzer et al, 1998;Rubanov and Munroe, 2001) and thus creates Ga-rich phases with Ga fractions of up to 20 wt % in the damage layer (Susnitzky and Johnson, 1998) and up to 30 wt % in the redeposition layer (Rajsiri et al, 2002), which can melt at low temperatures (Li and Liu, 2017). The sputtered material might redeposit on the surface in some cases (Rajsiri et al, 2002).…”

“…In addition, microstructural modifications from FIB milling of metals and ceramics have been reported, e.g., for copper (Cu) (Michael, 2006) and in manganite thin films (Balcells et al, 2008;Pallecchi et al, 2008). FIB preparations can result in reduced crystallinity of the material by generating point defects such as vacancies, interstitials, and antisite defects, due to charging effects (Li and Liu, 2017;Siemons et al, 2014), and these defects can even exceed the Ga + ion implantation depths, e.g., in BiFeO 3 (Siemons et al, 2014).…”

“…Sample heating also facilitates the occurrence of uncommon types of beam damage, such as preferential sputtering (Volkert and Minor, 2007), which occurs in materials with more than one atom species, especially if the compound can decompose chemically. In-depth information on sample heating (Kim and Carpenter, 1987;Cen and Van Benthem, 2018;Volkert and Minor, 2007;Ovchinnikov et al, 2015;Ishitani and Kaga, 1995), beam damage (Gutierrez-Urrutia, 2017;Mayer et al, 2007;Betz and Wehner, 1983;Prenitzer et al, 2003), and experimental reduction strategies of these effects (Bassim et al, 2012;Barber, 1993) can be found in the cited literature.…”