High-flux low-energy ({congruent}20 eV) N{sup +}{sub 2} ion irradiation during TiN deposition by reactive magnetron sputtering: Effects on microstructure and preferred orientation
- Thin Film Division, Physics Department, Linkoeping University, S-581 83 Linkoeping (Sweden)
- Department of Materials Science, the Coordinated Science Laboratory, and the Materials Research Laboratory, University of Illinois, 1101 West Springfield Avenue, Urbana, Illinois, 61801 (United States)
The effects of the incident ion/metal flux ratio (1{le}{ital J}{sub {ital i}} /{ital J}{sub Ti}{le}15), with the N{sup +}{sub 2} ion energy {ital E}{sub {ital i}} constant at {congruent}20 eV ({congruent}10 eV per incident accelerated N), on the microstructure, texture, and stoichiometry of polycrystalline TiN films grown by ultrahigh-vacuum reactive-magnetron sputtering have been investigated. The layers were deposited in pure N{sub 2} discharges on thermally oxidized Si(001) substrates at 350 {degree}C. All films were slightly overstoichiometric with a N/Ti ratio of 1.02 and a lattice constant of 0.4240 equal to that of unstrained bulk TiN. Films deposited with {ital J}{sub {ital i}}/{ital J}{sub Ti}=1 initially exhibit a mixed texture---predominately (111), (002), and (022)---with competitive columnar growth which slowly evolves into a pure (111) texture containing a network of both inter- and intracolumn porosity with an average column size of {congruent}50 nm at {ital t}=1.6 {mu}m. In contrast, films grown with {ital J}{sub {ital i}}/{ital J}{sub Ti}{ge}5 do not exhibit competitive growth. While still columnar, the layers are dense with an essentially complete (002) preferred orientation and an average column size of {congruent}55 nm from the earliest observable stages. The normalized x-ray diffraction (002) intensity ratio in thick layers increased from {congruent}0 to 1 as {ital J}{sub {ital i}}/{ital J}{sub Ti} was varied from 1 to {ge}5. Both 111 and 001 interplanar spacings remained constant as a function of film thickness for all {ital J}{sub {ital i}}/{ital J}{sub Ti}. Thus strain is not the dominant factor in controlling the development of preferred orientation in these films. Moreover, once film texture is fully evolved---whether it be (002) or (111)---during deposition, changing {ital J}{sub {ital i}}/{ital J}{sub Ti} has little effect as preferred orientation becomes controlled by pseudomorphic forces. (Abstract Truncated)
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- DOE Contract Number:
- AC02-76ER01198
- OSTI ID:
- 122985
- Journal Information:
- Journal of Applied Physics, Vol. 78, Issue 9; Other Information: PBD: 1 Nov 1995
- Country of Publication:
- United States
- Language:
- English
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