X-ray reflectometry and grazing-incidence X-ray fluorescence characterization of innovative electrodes for tantalum-based resistive random access memories

• Published in: Spectrochimica acta. Part B: Atomic spectroscopy Vol. 149; pp. 71 - 75
• Main Authors: Nolot, E., Caby, B., Gassilloud, R., Veillerot, M., Eichert, D.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier B.V 01.11.2018; Elsevier BV; Elsevier
• Subjects: Combined analysis; Electrode materials; Electrodes; Engineering Sciences; Fluorescence; Grazing; Grazing incidence; Grazing-incidence X-ray fluorescence; Heavy metals; Multilayers; Nickel; Nondestructive testing; Organic chemistry; Oxidation; Profiles; Random access; Random access memory; Reflectometry; Resistive memory; Spectrum analysis; Tantalum; Tantalum oxides; Time-Of-Flight Secondary Ion Mass Spectrometry; Titanium nitride; X-ray fluorescence; Resistive memory; Time-Of-Flight Secondary Ion Mass Spectrometry; Combined analysis; Grazing-incidence X-ray fluorescence; Spectrometry; Time-Of-Flight Secondary Ion Mass
• ISSN: 0584-8547; 1873-3565
• DOI: 10.1016/j.sab.2018.07.017

We evaluate the ability of the combination of grazing-incidence X-ray fluorescence (GIXRF) with X-ray reflectometry (XRR) to probe the impact of variations in the deposition process of tantalum oxide on the chemical depth-profiles of Ta2O5/metal structure, titanium nitride and nickel being investigated as bottom electrode material as they are good candidates for the replacement of noble materials by low-cost fab-friendly abundant electrodes for Resistive RAM. TOF-SIMS and GIXRF/XRR both unambiguously demonstrate the significant TiN-Ta intermixing in Ta2O5/TiN stacks, even with optimized Ta2O5 process conditions. On the contrary, TOF-SIMS profiles reveal that the introduction of H* plasma step in PE-ALD Ta2O5 process drastically reduces both the oxidation of nickel electrode material and the Ta2O5/Ni intermixing, therefore confirming that nickel is a good candidate for Ta2O5 based ReRAM. The influence of H* plasma on nickel-based samples was also evidenced by GIXRF/XRR technique, first qualitatively, then quantitatively by the use of model-based multilayer combined analysis, therefore demonstrating the performances of GIXRF/XRR as highly-sensitive, non-destructive chemical depth-profile technique suitable to support process development, either in lab or even in fabs. [Display omitted] •Expensive noble metals are used as electrodes for Resistive RAM.•Titanium nitride and nickel are investigated as low-cost fab-friendly electrodes.•GIXRF/XRR analysis evidenced that nickel was a good candidate for Ta2O5 ReRAM.•TOF-SIMS analysis is aligned with GIXRF/XRR non-destructive characterization.