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The Co-Reactant Role During Plasma Enhanced Atomic Layer Deposition of Palladium

Ji-Yu Feng, Matthias M Minjauw, Ranjith K Ramachandran, Michiel Van Daele, Hilde Poelman, Timo Sajavaara, Jolien Dendooven, Christophe Detavernier

Phys Chem Chem Phys. 2020 Apr 29;22(16):9124-9136.

PMID: 32301468

Abstract:

Atomic layer deposition (ALD) of noble metals is an attractive technology potentially applied in nanoelectronics and catalysis. Unlike the combustion-like mechanism shown by other noble metal ALD processes, the main palladium (Pd) ALD process using palladium(ii)hexafluoroacetylacetonate [Pd(hfac)2] as precursor is based on true reducing surface chemistry. In this work, a thorough investigation of plasma-enhanced Pd ALD is carried out by employing this precursor with different plasmas (H2*, NH3*, O2*) and plasma sequences (H2* + O2*, O2* + H2*) as co-reactants at varying temperatures, providing insights in the co-reactant and temperature dependence of the Pd growth per cycle (GPC). At all temperatures, films grown with only reducing co-reactants contain a large amount of carbon, while an additional O2* in the co-reactant sequence helps to obtain Pd films with much lower impurity concentrations. Remarkably, in situ XRD and SEM show an abrupt release of the carbon impurities during annealing at moderate temperatures in different atmospheres. In vacuo XPS measurements reveal the remaining species on the as-deposited surface after every exposure. Links are established between the particular surface termination prior to the precursor pulse and the observed differences in GPC, highlighting hydrogen as the key growth facilitator and carbon and oxygen as growth inhibitors. The increase in GPC with temperature for ALD sequences with H2* or NH3* prior to the precursor pulse is explained by an increase in the amount of hydrogen species that reside on the Pd surface which are available for reaction with the Pd(hfac)2 precursor.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP64916489 Palladium(II) hexafluoroacetylacetonate Palladium(II) hexafluoroacetylacetonate 64916-48-9 Price
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