SrTa{sub 2}O{sub 6} thin films for high-K dielectric applications grown by chemical vapor deposition on different substrates

Journal Article · Fri Apr 01 00:00:00 EST 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1873033· OSTI ID:20668277

Regnery, Stephan; Thomas, Reji; Ehrhart, Peter; Waser, Rainer ^[1]

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1. Institut fuer Festkoerperforschung and Center of Nanoelectronic Systems for Information Technology, Forschungszentrum Juelich, D-52425 Juelich (Germany)

SrTa{sub 2}O{sub 6} thin films with thickness between 6 and 150 nm were deposited by metal-organic chemical vapor deposition in a multiwafer planetary reactor. The monomolecular precursor, strontium-tantalum-(methoxyethoxy)-ethoxide, was dissolved in toluene and injected by a liquid delivery system. A rather narrow process window for the deposition of stoichiometric SrTa{sub 2}O{sub 6} was found for this precursor at low pressures and a susceptor temperature around 500 deg. C. Films were grown on Pt/TiO{sub 2}/SiO{sub 2}/Si, TiN{sub x}/Si, and SiO{sub 2}/Si substrates. The as-deposited films were x-ray amorphous and could be crystallized by postannealing at a temperature {>=}700 deg. C. The distorted tetragonal tungsten bronze phase of SrTa{sub 2}O{sub 6} was dominating within a broad range of compositions (Sr/Ta: 0.4-0.7) and a perovskite-type phase was additionally observed for Sr/Ta>0.7 and predominated for Sr/Ta>1. The electrical properties have been investigated with metal-insulator-metal and metal-insulator-semiconductor capacitors after sputter deposition of Pt top electrodes. The amorphous films had a dielectric constant K in the range of 35-45 and low leakage currents. For stoichiometric SrTa{sub 2}O{sub 6} the dielectric permittivity reached values of K=100-110, but the leakage currents were increased. Remarkably, the permittivity is not very sensitive to deviations from the exact stoichiometry of the SrTa{sub 2}O{sub 6} phase (Sr/Ta: 0.4-0.7), but a decrease to values of K=30-40 is observed along with the transition to the perovskite phase at high Sr contents.

• OSTI ID: 20668277
• Journal Information: Journal of Applied Physics, Vol. 97, Issue 7; Other Information: DOI: 10.1063/1.1873033; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
CAPACITORS
CHEMICAL VAPOR DEPOSITION
CRYSTALLIZATION
LEAKAGE CURRENT
PERMITTIVITY
PLATINUM
SILICON
SILICON OXIDES
STOICHIOMETRY
STRONTIUM COMPOUNDS
SUBSTRATES
TANTALATES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0400-1000 K
THIN FILMS
TITANIUM NITRIDES
TITANIUM OXIDES
TOLUENE
TUNGSTEN BRONZE