The STATE of the art - XPS Dr Chris Blomfield Dr Adam Roberts, Dr Simon Hutton Kratos Analytical Ltd A Shimadzu Group Company
Distribution of XPS instruments A Shimadzu Group Company 56% Industrial 44% Academic
What are we missing out on? Sate of the art instruments offer: –Improved sensitivity improved detection limits reduced acquisition time –Smaller spot sizes ~ 5 m spot size available –XPS imaging 3 m spatial resolution A Shimadzu Group Company
3 decades of improvement A Shimadzu Group Company Ag 3d 5/2 FWHM Mono0.6eV Mg1.0eV
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 A Shimadzu Group Company
-CP process PE-COOCOR i) PTBA ii) MeSO 3 H alkyl amine hyperbranched PAA film PDMS stamp Oxidised PE substrate A Shimadzu Group Company alkyl amine Passivated layer Unpassivated region
PAA on Au films Au 4f photoelectron image attenuation of Au substrate gives contrast mechanism Au substrate PAA layer alkyl amine A Shimadzu Group Company
C 1s - 27 m analysis area PAA C 1s from PAA layer A Shimadzu Group Company
Au 4f & C 1s image A Shimadzu Group Company
< 3 m spatial resolution
Fluorinated PAA on PE PE-COOCOR A Shimadzu Group Company Experiment repeated using PE substrate with PAA layer being fluorinated
C 1s spectra A 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 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 A Shimadzu Group Company
C1s chemical state image A 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 exposure A Shimadzu Group Company
In 3d quantification Overlap with Ca 2s In 3d 3/2 used for quantification A Shimadzu Group Company
Corrosion tests Cut anode surface used to represent bulk –XPS In0.02wt% –GDOESIn0.0185wt% As cast anode surface ~1wt% In Corrosion tests show an increase to 4wt% over 1 years simulated corrosion A Shimadzu Group Company
In & Fe conc versus dissolution time A Shimadzu Group Company
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 A Shimadzu Group Company
Optical image contact pad A Shimadzu Group Company
Wide scan - low concentrations O 1s7.53% C 1s37.0% Au 4f54.42% Co 2p0.78% Ni 2p0.27% A Shimadzu Group Company
High resolution Co2p and Ni 2p Co 2p 3/2 Ni 2p 3/2 Co oxide Co metal A Shimadzu Group Company
Polymer reflector contamination ca. 500 m Cross section through a “dimple” PP contamination A Shimadzu Group Company
Wide scan from 700 m area A Shimadzu Group Company
VB from 700 m area A Shimadzu Group Company
Valence band of PE & PP A Shimadzu Group Company
110 m spot size C 1s A Shimadzu Group Company
110 m spot size VB A Shimadzu Group Company VB in flat VB in hole PP character VB
Bond pad contamination A Shimadzu Group Company l Al 2p photoelectron image Optical image of Al pads in-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 A Shimadzu Group Company
Al 2p and F 1s images A Shimadzu Group Company F 1s image shows distribution of F on pads
Small spot spectroscopy A Shimadzu Group Company 55um spectra show Al/F on pad
Photoelectron images A Shimadzu Group Company F 1s and al 2p images shwo distribution of F across 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???? A Shimadzu Group Company
Acknowledgements -CP Richard Crooks Texas A & M University In anode John Norris & Morgan Alexander. CPC, UMIST, UK Polymer VB Gary Korba 3M Central Research Labs Minneapolis Paper sample James Tse Avery Dennison Pasedena. USA A Shimadzu Group Company