Atomic Layer Deposition of Iridium Thin Films

Thin films of metallic iridium were grown by atomic layer deposition (ALD) in a wide temperature range of 225-375°C from tris(2,4-pentanedionato)iridium [Ir(acac) 3 ] and oxygen. The films had low resistivity and low impurity contents and good adhesion to the substrate. The film growth rate saturated to a constant value as the precursor pulse times were increased, thus verifying the self-limiting growth mechanism. In addition, the film thickness depended linearly on the number of deposition cycles. The development of the surface morphology with increasing film thickness was studied by atomic force microscopy (AFM). AFM and X-ray reflectivity analysis showed that the films had smooth surfaces. The films showed a preferred (111) orientation as studied by X-ray diffraction. The results show that high-quality iridium films can be grown by ALD.

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