Electron-beam-induced deposition and post-treatment processes to locally generate cleantitanium oxide nanostructures on Si(100)

Abstract

We have investigated the lithographic generation ofTiOx nanostructures on Si(100) via electron-beam-induced deposition (EBID) of titaniumtetraisopropoxide (TTIP) in ultra-high vacuum (UHV) by scanning electron microscopy(SEM) and local Auger electron spectroscopy (AES). In addition, the fabricatednanostructures were also characterized ex situ via atomic force microscopy (AFM) underambient conditions. In EBID, a highly focused electron beam is used to locallydecompose precursor molecules and thereby to generate a deposit. A drawback ofthis nanofabrication technique is the unintended deposition of material in thevicinity of the impact position of the primary electron beam due to so-calledproximity effects. Herein, we present a post-treatment procedure to deplete theunintended deposits by moderate sputtering after the deposition process. Moreover,we were able to observe the formation of pure titanium oxide nanocrystals (<100 nm) in situ upon heating the sample in a well-defined oxygen atmosphere. While thenanocrystal growth for the as-deposited structures also occurs in the surroundings of theirradiated area due to proximity effects, it is limited to the pre-defined regions, if thesample was sputtered before heating the sample under oxygen atmosphere. The describedtwo-step post-treatment procedure after EBID presents a new pathway for the fabricationof clean localized nanostructures.