the state of the art - xps dr chris blomfield dr adam roberts, dr simon hutton kratos analytical ltd...

The STATE of the art - XPS

Dr Chris Blomfield

Dr Adam Roberts, Dr Simon HuttonKratos Analytical Ltd

www.kratos.com

A Shimadzu Group CompanyA Shimadzu Group Company

Distribution of XPS instruments

UK

France

Germany

UK accounts for <15% of "state of the art" XPS

Based upon last ~ 50 instrument sales


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


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


-CP process

PE-COOCOR

PE-COOCOR

PE-COOCOR

i) PTBA ii) MeSO3H

alkyl amine

hyperbranchedPAA film

PDMS stamp

Oxidised PE substrate


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


C 1s - 27 m analysis area

PAA

C 1s from PAA layer


Au 4f & C 1s imageA Shimadzu Group CompanyA Shimadzu Group Company


< 3m spatial resolution

Fluorinated PAA on PE

PE-COOCOR


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


A Shimadzu Group CompanyA Shimadzu Group Company O1s images variable FOV

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


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

4% over 1 year exposureA Shimadzu Group CompanyA Shimadzu Group Company

In 3d quantification

Overlap with Ca 2s

In 3d3/2 used for quantification


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


In & Fe conc versus dissolution time


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


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%


High resolution Co2p and Ni 2p

Co 2p3/2 Ni 2p3/2

Co oxide

Co metal


Polymer reflector contamination

ca. 500 m

Cross section through a “dimple”

PP contamination


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


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????


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


the state of the art - xps dr chris blomfield dr adam roberts, dr simon hutton kratos analytical ltd...

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