the state of the art - xps dr chris blomfield dr adam roberts, dr simon hutton kratos analytical ltd...
TRANSCRIPT
The STATE of the art - XPS
Dr Chris Blomfield
Dr Adam Roberts, Dr Simon HuttonKratos Analytical Ltd
www.kratos.com
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Distribution of XPS instruments
UK
France
Germany
UK accounts for <15% of "state of the art" XPS
Based upon last ~ 50 instrument sales
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56% Industrial44% Academic
What are we missing out on?
• Sate of the art instruments offer:– Improved sensitivity
• improved detection limits
• reduced acquisition time
– Smaller spot sizes• ~ 5m spot size available
– XPS imaging • 3 m spatial resolution
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3 decades of improvementA Shimadzu Group CompanyA Shimadzu Group Company
Ag 3d5/2
FWHMMono 0.6eVMg 1.0eV
Applications to -CP
• Patterning of polymer substrate (polyethylene PE) with poly(acrylic) acid PAA.– PAA impermeable, wet and dry etch resist
– PAA films easily functionalised
– capped with PEG can be used for bio-applications cell growth
• Oxidised PE film is prepared
• PDMS stamp (optical mask) prepared with n-alkylamine
• PE “stamped” with amine to passivate PE
• Unpassivated regions react with PTBA
• Hydrolysis of this layer leads to PAA
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-CP process
PE-COOCOR
PE-COOCOR
PE-COOCOR
i) PTBA ii) MeSO3H
alkyl amine
hyperbranchedPAA film
PDMS stamp
Oxidised PE substrate
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alkyl amine
Passivated layer Unpassivated region
PAA on Au films
Au 4f photoelectron imageattenuation of Au substrategives contrast mechanism
Au substrate
PAA layer
alkyl amine
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C 1s - 27 m analysis area
PAA
C 1s from PAA layer
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Au 4f & C 1s imageA Shimadzu Group CompanyA Shimadzu Group Company
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< 3m spatial resolution
Fluorinated PAA on PE
PE-COOCOR
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Experiment repeated usingPE substrate with PAA layer being fluorinated
C 1s spectraA Shimadzu Group CompanyA Shimadzu Group Company
Adhesive coverage on paper
• Inhomogeneous paper sample with uneven coverage of adhesive - lead to adhesive failure
• Optically - sample was homogenous - white
• XPS O1s image clearly identifies adhesive distribution
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Chemical state images
• C1s image allows investigation of chemistry– small spot analysis shows variation in C-H and
C-O
• Energy resolution of SMA allows chemical imaging of different C 1s species
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C1s chemical state imageA Shimadzu Group CompanyA Shimadzu Group Company
Indium in commercial Al-Zn-In sacrificial anode
• Improved detection limits<0.05% allow analysis of low concentrations of elements
– Al-Zn-In anodes are used to protect marine steel structures from corrosion.
– study with XPS of the active In element – reveals surface segregation to a maximum of
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In 3d quantification
Overlap with Ca 2s
In 3d3/2 used for quantification
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Corrosion tests
• Cut anode surface used to represent bulk– XPS In 0.02wt%
– GDOES In 0.0185wt%
• As cast anode surface ~1wt% In
• Corrosion tests show an increase to 4wt% over 1 years simulated corrosion
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In & Fe conc versus dissolution time
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Summary
• In is surface segregated to Anode surface compared to the bulk - inverse segregation
• In is believed to segregate to the metal:oxide interface a more active surface
• Shows the activity of the anode is a surface phenomena - possible to investigate with improved detection limits
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Optical image contact padA Shimadzu Group CompanyA Shimadzu Group Company
Wide scan - low concentrations
O 1s 7.53%C 1s 37.0%Au 4f 54.42%Co 2p 0.78%Ni 2p 0.27%
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High resolution Co2p and Ni 2p
Co 2p3/2 Ni 2p3/2
Co oxide
Co metal
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Polymer reflector contamination
ca. 500 m
Cross section through a “dimple”
PP contamination
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Wide scan from 700m areaA Shimadzu Group CompanyA Shimadzu Group Company
VB from 700m areaA Shimadzu Group CompanyA Shimadzu Group Company
Valence band of PE & PPA Shimadzu Group CompanyA Shimadzu Group Company
110m spot size C 1sA Shimadzu Group CompanyA Shimadzu Group Company
110m spot size VBA Shimadzu Group CompanyA Shimadzu Group Company
VB in flat VB in hole
PP character VB
Bond pad contaminationA Shimadzu Group CompanyA Shimadzu Group Company
l
Al 2p photoelectron image
Optical image of Al padsin-situ
Bond pad contamination
• Bad adhesion was observed in Al bond pads
• Optical images was used to identify area of know failure
• XPS images and small spot show F contamination
• Distribution of F indicates residue from plasma etching step in production
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Al 2p and F 1s imagesA Shimadzu Group CompanyA Shimadzu Group Company
F 1s image showsdistribution of F on pads
Small spot spectroscopyA Shimadzu Group CompanyA Shimadzu Group Company
55um spectra showAl/F on pad
Photoelectron imagesA Shimadzu Group CompanyA Shimadzu Group Company
F 1s and al 2p imagesshwo distribution of Facross bond pad
Summary
• Modern XPS instruments are very powerful analytical tools
• As well as improved automation, reliability and accuracy:– imaging, detection limits, resolution, -
probe.....
• How to get more instruments into UK????
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Acknowledgements
-CPRichard Crooks Texas A & M University
In anodeJohn Norris & Morgan Alexander. CPC, UMIST, UK
Polymer VB Gary Korba 3M Central Research Labs Minneapolis
Paper sampleJames Tse Avery Dennison Pasedena. USA
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