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The co-reactant role during plasma enhanced atomic layer deposition of palladium

Year of publication

2020

Authors

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

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.
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Organizations and authors

Publication type

Publication format

Article

Parent publication type

Journal

Article type

Original article

Audience

Scientific

Peer-reviewed

Peer-Reviewed

MINEDU's publication type classification code

A1 Journal article (refereed), original research

Publication channel information

Volume

22

Issue

16

Pages

9124-9136

​Publication forum

65018

​Publication forum level

2

Open access

Open access in the publisher’s service

No

Self-archived

No

Other information

Fields of science

Physical sciences; Chemical sciences

Keywords

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Publication country

United Kingdom

Internationality of the publisher

International

Language

English

International co-publication

Yes

Co-publication with a company

No

DOI

10.1039/d0cp00786b

The publication is included in the Ministry of Education and Culture’s Publication data collection

Yes