Atomic layer deposition of artificially structured dielectric materials

Kaupo Kukli
Abstract & Cover

Artificially structured dielectric materials — thin films, mixtures of metal oxides and nanolaminates of Ta205, Hf02, Zr02, Nb205 and A1203 — can be successfully grown in atomic layer chemical vapour deposition (AL-CVD) process. Advanced dielectric properties can be obtained in the films grown at temperatures as low as 200-230°C. The dielectric performance of the binary metal oxides is determined by their chemical nature and structure. In certain extent, the residue content, film density and dielectric permittivity can be improved by increasing the deposition temperature or using better precursors. Further improvement in the film quality can be achieved by aiming at the formation of high-permittivity solid solutions by mixing different oxides like Ta205 and Nb205. The leakage currents can also be decreased by making use of the nanocrystalline nature of ultrathin Zr02 or Hf02 layers between amorphous Ta205 or (Nb^Ta^Os constraints in the multi layer structures. The charge storage capability of such advanced dielectric struc tures may be increased by ten times compared to the binary materials. It is obvious that, besides inherent thickness control, AL-CVD technique allows the precise tuning of the film composition. Moreover, the control over size-dependent dielectric properties is achieved. These advantages can be used for creating high-quality structured materials applicable in (large area) micro electronics such as integrated circuit (IC) processing or TFEL devices.

Source of Information
Väino Sammelselg
University of Tartu
(Tartu, Estonia)
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