Dense fully 111-textured TiN diffusion barriers: Enhanced lifetime through microstructure control during layer growth
- Materials Science Department, Materials Research Laboratory, and Coordinated Science Laboratory, University of Illinois, 1101 West Springfield Avenue, Urbana, Illinois 61801 (United States)
Low-temperature deposition of TiN by reactive evaporation or sputter deposition onto amorphous substrates leads to highly underdense layers which develop mixed 111/002 orientations through competitive growth. In contrast, we demonstrate here the growth of low-temperature (450&hthinsp;{degree}C) fully dense polycrystalline TiN layers with complete 111 texture. This was achieved by reactive magnetron sputter deposition using a combination of: (1) highly oriented 25-nm-thick 0002 Ti underlayers to provide 111 TiN orientation through texture inheritance (local epitaxy) and (2) high flux (J{sub N{sub 2}{sup +}}/J{sub Ti}=14), low-energy (E{sub N{sub 2}{sup +}}{approx_equal}20&hthinsp;eV), N{sub 2}{sup +} ion irradiation in a magnetically unbalanced mode to provide enhanced adatom diffusion leading to densification during TiN deposition. The Ti underlayers were also grown in a magnetically unbalanced mode, in this case with an incident Ar{sup +}/Ti flux ratio of 2 and E{sub Ar{sup +}}{approx_equal}11&hthinsp;eV. All TiN films were slightly overstoichiometric with a N/Ti ratio of 1.02{plus_minus}0.03. In order to assess the diffusion-barrier properties of dense 111-textured TiN, Al overlayers were deposited without breaking vacuum at 100&hthinsp;{degree}C. Al/TiN bilayers were then annealed at a constant ramp rate of 3thinsp{degree}Cthinsps{sup {minus}1} to 650thinsp{degree}Cthinsps{sup {minus}1} and the interfacial reaction between Al and TiN was monitored by {ital in situ} synchrotron x-ray diffraction measurements. As a reference point, we find that interfacial Al{sub 3}Ti formation is observed at 450&hthinsp;{degree}C in Al/TiN bilayers in which the TiN layer is deposited directly on SiO{sub 2} in a conventional magnetically balanced mode and, hence, is underdense with a mixed 111/002 orientation. However, the onset temperature for interfacial reaction was increased to 610&hthinsp;{degree}C in bilayers with fully dense TiN exhibiting complete 111 preferred orientation. {copyright} {ital 1999 American Institute of Physics.} thinsp
- OSTI ID:
- 689924
- Journal Information:
- Journal of Applied Physics, Vol. 86, Issue 7; Other Information: PBD: Oct 1999
- Country of Publication:
- United States
- Language:
- English
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