An effective postgrowth electrical tuning, via an oxygen releasing method, to enhance the content of non-noble metals in deposits directly written with gas-assisted focused-electron-beam-induced deposition (FEBID) is presented. It represents a novel and reproducible method for improving the electrical transport properties of Co-C deposits. The metal content and electrical properties of Co-C-O nanodeposits obtained by electron-induced dissociation of volatile Co(CO) precursor adsorbate molecules were reproducibly tuned by applying postgrowth annealing processes at 100 °C, 200 °C, and 300 °C under high-vacuum for 10 min. Advanced thin film EDX analysis showed that during the annealing process predominantly oxygen is released from the Co-C-O deposits, yielding an atomic ratio of Co:C:O = 100:16:1 (85:14:1) with respect to the atomic composition of as-written Co:C:O = 100:21:28 (67:14:19). In-depth Raman analysis suggests that the amorphous carbon contained in the as-written deposit turns into graphite nanocrystals with size of about 22.4 nm with annealing temperature. Remarkably, these microstructural changes allow for tuning of the electrical resistivity of the deposits over 3 orders of magnitude from 26 mΩ cm down to 26 μΩ cm, achieving a residual resistivity of ρ/ρ = 0.56, close to the value of 0.53 for pure Co films with similar dimensions, making it especially interesting and advantageous over the numerous works already published for applications such as advanced scanning-probe systems, magnetic memory, storage, and ferroelectric tunnel junction memristors, as the graphitic matrix protects the cobalt from being oxidized under an ambient atmosphere.

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Articles you may be interested inDetermining factor of effective work function in metal/bi-layer high-k gate stack structure studied by photoemission spectroscopy Appl. Phys. Lett. 100, 112906 (2012); 10.1063/1.3695166 Photoinduced charge-trapping phenomena in metal/high-k gate stack structures studied by synchrotron radiation photoemission spectroscopy Appl. Phys. Lett. 96, 162902 (2010); 10.1063/1.3409162 Thermally stable high effective work function TaCN thin films for metal gate electrode applications Titanium nitride (TiN) films have been used as gate electrode on metal-oxide-semiconductor (MOS) devices. TiN effective work function (EWF) values have been often reported as suitable for pMOS. For nMOS devices, a gate electrode with sufficient low EWF value with a similar robustness as TiN is a challenge. Thus, in this work, aluminum (Al) is incorporated into the TiN layer to reduce the EWF values, which allows the use of this electrode in nMOS devices. Titanium aluminum (TiAl), Al, and aluminum nitride (AlN) layers were introduced between the high-k (HfO 2 ) dielectric and TiN electrode as Al diffusion sources. Pt/TiN (with Al diffusion) and Pt/TiN/TiAl/TiN structures were obtained and TiN EWF values were reduced of 0.37 eV and 1.09 eV, respectively. The study of TiN/AlN/HfO 2 /SiO 2 /Si/Al structures demonstrated that AlN layer can be used as an alternative film for TiN EWF tuning. A decrease of 0.26 eV and 0.45 eV on TiN EWF values were extracted from AlN/TiN stack and AlN/TiN laminate stack, respectively. AlN/TiN laminate structures have been shown to be more effective to reduce the TiN work function than just increasing the AlN thickness. V C 2014 AIP Publishing LLC.

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