Probing ultrathin film continuity and interface abruptness with x-ray photoelectron spectroscopy and low-energy ion scattering
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853 (United States)
- Applied Materials, 3320 Scott Blvd, Santa Clara, California 95054 (United States)
The authors have examined ultrathin (≤10 Å) tantalum nitride (TaN{sub x}) thin films deposited by atomic layer deposition (ALD) on three surfaces relevant to interconnect layers in microelectronic devices: thermally grown SiO{sub 2}; a Cu thin film grown by physical vapor deposition, and a carbon-doped SiO{sub 2} porous low-κ thin film. The authors have employed ex situ angle-resolved x-ray photoelectron spectroscopy (ARXPS), low-energy ion scattering spectroscopy (LEISS), and atomic force microscopy (AFM) to determine the continuity of these thin films, and by implication, the abruptness of the thin film/substrate interface. On SiO{sub 2} and low-κ, the authors find similar results: both ARXPS and AFM indicate that smooth, uniform thin films are deposited, consistent with nearly layer-by-layer growth of TaN{sub x} on these surfaces. Examination of these films using LEISS reveals that while the 10 Å TaN{sub x} thin films are continuous, the 5 Å TaN{sub x} thin films are not continuous and may possess on the order of ∼10% exposed substrate in the form of small subnanometer inclusions. On Cu, the situation is quite different. The TaN{sub x} thin films on these surfaces are not continuous, and our results point to a mixed layer of TaN{sub x} and Cu forming during ALD. In all cases, if one were to rely solely on results from ARXPS, the picture would be incomplete as the results from LEISS are ultimately decisive concerning thin film continuity.
- OSTI ID:
- 22224099
- Journal Information:
- Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Vol. 31, Issue 6; Other Information: (c) 2013 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0734-2101
- Country of Publication:
- United States
- Language:
- English
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