High Temperature Atomic Layer Deposition of Ruthenium from N,N-Dimethyl-1-ruthenocenylethylamine

Abstract

Ruthenium thin films were grown by atomic layer deposition from N,N -dimethyl-1-ruthenocenylethylamine precursor. The growth was examined in the substrate temperature range of 325–500°C . The growth rate increased with the substrate temperature but was quite stable between 400 and 450°C . The films typically consisted of polycrystalline hexagonal ruthenium metal with a resistivity in the range of 10–20μΩcm when the film thickness was 10 nm and above. A resistivity of 49μΩcm could be achieved in the film as thin as 4 nm. Measurements on Al/Al2normalO3/Ru metal-insulator-metal (MIM) capacitors with Ru films as metal electrodes revealed a capacitive voltage behavior typical of MIM structures and appreciably high breakdown voltages.

Atomic layer deposition of Ru from CpRu(CO)2Et using O2 gas and O2 plasma

“…This is about twice as high as the growth obtained with other metalorganic precursors, such as Ru͑EtCp͒ 2 , DER, or EMR. 21,24,31 The growth-per-cycle is, however, quite similar to one of the new Ru ALD processes recently reported by Eom et al 30 Using the open-ring compound C 16 H 22 Ru, a similarly high growth-per-cycle of 0.9 Å was obtained at 220°C.…”

“…However, based on the results reported, the high surface roughness can mainly be attributed to the combination of a relatively high substrate temperature and use of O 2 ͑plasma͒ as co-reactant. 12 roughness values ͑1.7 nm for a 5 nm thin film͒ for Ru prepared from EMR and O 2 at high substrate temperatures ͑T ϳ 400°C͒, 31 and Park et al 33 reported a surface roughness of 1.4 nm for a film of only ϳ3.1 nm thickness prepared from CpRu͑CO͒ 2 Et and O 2 at 300°C. Using a ruthenium amidanate precursor and O 2 , Wang et al 32 found that the surface roughness and grain size increase with longer O 2 gas exposures ͑with a maximum roughness of ϳ2.5 nm for an ϳ30 nm thick film͒ with the grain size distribution becoming also non-uniform.…”

“…Similar polycrystalline films have been obtained by several other Ru ALD processes using metalorganic precursors and O 2 gas. 12,31,39 Since the relative peak intensities resemble those of the reference spectrum of a powder sample the crystallites in the Ru layer have no dominant crystallographic orientation, although it cannot be excluded that the film prepared by plasma-assisted ALD might be slightly preferentially oriented in the ͑002͒ and ͑101͒ planes. In a comparison between Ru ALD with O 2 gas and NH 3 plasma, Kwon et al 24 also observed a ͑002͒ preferential orientation when a NH 3 plasma was used.…”

“…The root-mean-square ͑rms͒ roughness values of these ALD films, 5 and 9.6 nm for the thermal and plasma-assisted ALD films, respectively, are very high for ALD films compared to the surface roughness values reported so far. For thermal ALD of Ru, rms surface roughness values are typically within the range of 0.3-3.8 nm ͑for film thicknesses ranging from 5 to 80 nm͒, 18,31,32,40 while for plasma-assisted ALD films even values as low as 0.7 nm have been reported for 50 nm thick films. 24 The results from the TEM measurements on the TiNcovered membranes are shown in Fig.…”

Structure and morphology of Ru films grown by atomic layer deposition from 1-ethyl-1’-methyl-ruthenocene

“…To mention a few, (2,4-dimethylpentadienyl) (ethylcyclopentadienyl)ruthenium [24], bis (2,4-dimethylpentadienyl) ruthenium [25], triruthenium dodecacarbonyl [9] and bis(2,2,6, 6-tetramethyl-heptane-3,5-dionato)(1,5-cyclooctadiene)ruthenium [26], have been applied as Ru precursors in CVD process. Bis(cyclopentadienyl)ruthenium [18][19][20], bis(ethylcyclopentadienyl)ruthenium [19,27], N,N-dimethyl-1-ruthenocene [28], 2,4-(dimethylpentadienyl) (ethylcyclopentadienyl) ruthenium, i.e. DER [29], (methylcyclopentadienyl)(pyrrolyl)ruthenium [15] or isopropylmethylbenzene-cyclohexadiene-ruthenium [2] have been adapted to ALD processes.…”