Atomic Layer Deposition of Iridium Oxide Thin Films from Ir(acac)₃ and Ozone

Abstract

Iridium oxide thin films were grown with atomic layer deposition (ALD) from Ir(acac) 3 and ozone between 165 and 200 °C. The films were successfully deposited on soda lime glass, silicon substrate with native oxide, and Al 2 O 3 adhesion layer. Saturation of the growth rate with respect to both precursors was verified and the film thickness depended linearly on the number of deposition cycles applied. The iridium oxide films had low impurity contents and good adhesion to all tested surfaces. IrO 2 film deposited at 185 °C had homogeneous depth profile and contained 3.5 at % hydrogen and less than 0.5 at % carbon impurities. Resistivities of about 40 nm thick IrO 2 films varied between 170 and 200 µΩ cm. The films deposited above 200 °C were metallic iridium. All the films deposited were crystalline according to X-ray diffraction patterns.

Remote Plasma ALD of Platinum and Platinum Oxide Films

“…20 For the process employing Pt͑acac͒ 2 and O 3 , only a small temperature window was observed ͑120-130°C͒. 13 Therefore, the large temperature window of our PtO 2 process suggests a higher stability of the material, which can most likely be related to the higher oxygen content ͑PtO 2.2 compared to PtO 1.6 ͒.…”

“…For the process employing Pt͑acac͒ 2 and O 3 , a lower resistivity ͑1.5-5 ⍀ cm͒ was reported most probably due to a lower O content ͑PtO 1.6 ͒. 13,20 The Table I. The starting substrate at 0 cycles was Si͑100͒ with 400 nm SiO 2 .…”

“…After 150 cycles of remote plasma ALD, the Pt film growth is continued by thermal ALD. PtO 2 film is amorphous or nanocrystalline, 13 and no diffraction peaks from the ␣ and ␤ PtO 2 phases can be identified in the XRD spectra. 8 Temperature dependence.- Figure 4 shows the growth per cycle for the three processes over a wide temperature range.…”

“…11,12 For PtO x only one ALD process has been reported, to the best of our knowledge. 13 PtO x films were obtained from the combination of Pt͑acac͒ 2 ͑acac = acetylacetonate͒ and O 3 in the small temperature window of 120-130°C. 13 In this article, ALD processes are reported for Pt and PtO 2 from the combination of MeCpPtMe 3 precursor and O 2 plasma exposure.…”

“…13 PtO x films were obtained from the combination of Pt͑acac͒ 2 ͑acac = acetylacetonate͒ and O 3 in the small temperature window of 120-130°C. 13 In this article, ALD processes are reported for Pt and PtO 2 from the combination of MeCpPtMe 3 precursor and O 2 plasma exposure. In the O 2 plasma, O radicals are created, providing atomic O to the surface directly from the gas phase, enhancing oxygen chemisorption and oxidation.…”