| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Thin Films | Tuesday Sessions |
| Session TF-TuM |
| Session: | Nanostructured Surfaces & Thin Films II |
| Presenter: | Elham Mohimi, University of Illinois at Urbana-Champaign, USA |
| Authors: | E. Mohimi, University of Illinois at Urbana-Champaign, USA B.B. Trinh, University of Illinois at Urbana-Champaign, USA S. Babar, University of Illinois at Urbana-Champaign, USA G.S. Girolami, University of Illinois at Urbana-Champaign, USA J.R. Abelson, University of Illinois at Urbana-Champaign, USA |
| Correspondent: | Click to Email |
Manganese and iron nitride phases are an interesting class of materials for applications such as optoelectronics, microelectronics, magnetic recording, and spintronics. Since chemical vapor deposition (CVD) can conformally coat high aspect ratio (deep) features used in design of nanoscale devices, it is highly desirable to develop CVD routes for manganese and iron nitride films. However, the lack of suitable precursors has hindered this development.
Here, we report CVD growth of manganese and iron nitride films from a novel and practical precursor, bis(2,2,6,6 tetramethylpiperidido)metal (II), M (tmp)2, with ammonia as co-reactant. The manganese and iron tmp complexes can be synthesized in high yield and are thermally stabile at room temperature. Growths are done in a cold wall, high vacuum chamber at substrate temperature of 50-350 °C. Precursors are heated to 60-75°C and delivered to the chamber using Ar carrier gas at flow rates of 5-40 sccm. Anhydrous ammonia is delivered through a separate line to afford a partial pressure of 0-13 mTorr.
XPS reveals a compositional ratio of Mn:N = 2.6:1 to 2.8:1 for manganese nitride (MnxNy) and Fe:N = 4.1:1 for iron nitride (FexN) films grown in the temperature range examined, with no carbon contamination within the detection limits of instrument. All films show a slightly columnar microstructure in cross-section SEM. While there was a few min of nucleation delay for MnxNy growth at 150 °C, no nucleation delay was observed for FexN under the same growth conditions. There is no film growth at all in the absence of ammonia; this indicates that transamination is required to create Mn-NH2 groups that react on the substrate surface to form the nitride film, as seen for film growth from other metal amido precursors in the presence of ammonia. Films are conformal in micro-trenches of aspect ratio 3; the thickness profiles are, however, characteristic of film growth from two reactive species, one with high and one with low sticking coefficient at the film surface. Copper diffusion barrier properties of a 12 nm manganese nitride film are investigated by annealing a test structure of 200 nm Cu / 12 nm MnxNy / 300 nm SiO2 / Si at 500 °C under Ar for 1 hour. Auger electron spectroscopy depth profiles show that manganese nitride performs well as copper diffusion barrier for microelectronic applications.