Strengthening TiN diffusion barriers for Cu metallization by lightly doping Al

Journal Article · Mon Sep 19 00:00:00 EDT 2005 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.2056583· OSTI ID:20709791

Yang, L C; Hsu, C S; Chen, G S; Fu, C C; Zuo, J M; Lee, B Q ^[1]

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1. Department of Materials Science and Engineering, National Formosa University, Yunlin 632, Taiwan (China)

Thin films of Ti{sub 1-x}Al{sub x}N were deposited on (100) Si by ultrahigh-vacuum dual-target reactive sputtering, and the impact of lightly doping Al of x as small as 0.09 on altering the films's microstructure upon thermal annealing, and hence the performance of the films (40 nm thick) as diffusion barriers for Cu metallization was evaluated. The results of transmission electron microscopy, Rutherford backscattering spectroscopy, and grazing-incidence x-ray diffraction show that the TiN barrier layer gives the commonly observed voided, columnar grains composed of 5 nm sized subgrains. Upon annealing, the subgrains tend to coalesce into 20 nm sized equiaxed grains full of crystalline defects, initiating an inward penetration of Cu and a partial dissociation of TiN, transforming themselves, respectively, into pyramidal (or columnar) Cu{sub 3}Si precipitates and a dendritic Ti{sub 5}Si{sub 3} layer just after 550 deg. C, 10 min annealing. However, the lightly doped Al not only overrides the tendency to form intercolumnar voids inherent in sputter deposition by self-shadowing and statistical roughening, but also substantially enhances the microstructural and thermochemical stability, hence significantly improving barrier property, as evidenced from an annealing test at an elevated temperature (600 deg. C) for a prolonged period of 30 min.

• OSTI ID: 20709791
• Journal Information: Applied Physics Letters, Vol. 87, Issue 12; Other Information: DOI: 10.1063/1.2056583; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ANNEALING
COPPER
COPPER SILICIDES
CRYSTAL DEFECTS
DENDRITES
DIFFUSION BARRIERS
DISSOCIATION
DOPED MATERIALS
MICROSTRUCTURE
PRECIPITATION
RUTHERFORD BACKSCATTERING SPECTROSCOPY
SPUTTERING
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
THIN FILMS
TITANIUM NITRIDES
TITANIUM SILICIDES
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION