Topics & Questions to Consider when Buying an XPS Instrument

Facilities manager
Operator(s) instrument experience
Support, repair, service people
Software & applications training
Standalone XPS processing software
Charge compensation

 

Note:
Modern XPS instruments provide high electron detection count-rates, a monochromator, automated control of energy resolution (via Pass Energies), a charge compensation system, an ion etching gun for milling, and Windows based software to operate the instrument and process the spectra data. Even so, there are significant differences in XPS instruments, the producers, the service cost, reliability, maintenance cost, cost of replacing boards, training, and basic operation of modern XPS instruments. 

Who will be responsible to operate, maintain, and train other users?

  • Professor
  • Graduate student
  • Group engineer
  • Instrument facility’s manager
  • Scientist
  • Group manager

Who will be responsible to contact service engineer when routine service or repair is needed?

  • Instrument facility’s manager
  • Group manager
  • Professor
  • Group engineer
  • Key Question:  How soon will service engineer arrive on site if needed?

Factors that often affect new Instrument Purchase

  • Pre-existing XPS instrument(s)
  • Influence from friends
  • Knowledge/experience with a previous XPS
  • Year of expected obsolescence
  • Quality of application support
  • Rate of sample degradation during routine analyses of insulating materials
  • Instrument specification compared to instrument performance
  • Ease of use of charge compensation on powders and rough surfaces
  • Does instrument provide automated BE calibration software (routine)?
  • Does instrument provide automated Transmission Function calibration routine?
  • Time required to pump down load-lock to transfer sample stage into analysis chamber
  • Will sale include 2 large monitors (32″), a wired mouse, and a large desk?
  • Does instrument include “auto-focus” or “auto-height” adjustment?
  • Will good optical focus through camera be same as good electronic focus
  • Will installer demonstrate that good camera focus is same as good electronic focus
  • Rumors?

User Training Questions

  • Where will instrument and software training be performed?
  • How many days of training will be provided?
  • How many people can attend the instrument training?
  • Number of days training one user at our facility
  • Number of people being trained at same time at maker facility
  • Instrument training manual provided
  • Instrument operation videos provided
  • Number of application notes provided
  • Videos showing how to use advanced data processing routines

Charge Compensation of Insulating Materials is Critical to Most XPS Analyses

  • Does your new XPS instrument have a reliable charge compensation system that is easy to adjust (XY position, voltage, flux)
  • You need to be sure because >60% of materials analyzed require Charge Compensation because >60% of materials are insulating
  • If charge compensation can not be optimized then problems such as peak broadening, differential charging and sample degradation will limit chemical information

FWHM of High Energy Resolution Peaks depends on Pass Energy, Quality of Charge Compensation and Potential Damage from Excessive or Un-needed X-ray Flux

  • The natural FWHM of the main XPS peak produced by >90% of all Insulating Materials ranges from 0.9 to 1.5 eV. Very, very few insulators give FWHM 0.8-0.9 eV
  • The most useful pass energy that should be used to measure chemical states of most insulating materials produces a FWHM ~0.7-0.8 eV for ion etched Ag (3d5)
  • Pass energies that produce Ag (3d5) FWHM < 0.7 eV will never decrease the FWHM of most insulating materials due to the natural limit of FWHM of insulators
  • Decreasing pass energy unnecessarily definitely exposes sample to excessive X-ray flux that will degrade chemistry the longer it is exposed to X-rays
  • Too small pass energy does not improve FWHM but exposes sample to excessive X-ray flux that can damage/degrade sample
  • Silver (3d5) FWHM is the best indicator to determine what Pass Energy to use when analyzing insulators.  
  • Require the XPS Instrument company to measure the Ag (3d5) FWHM as a function of Pass Energy for the same number of scans and send it to you
  • Some charge compensation systems may cause Adventitious Carbon to be desorbed as a function of exposure along a line profile scan

Key Charge Compensation Factors that Control Data Quality for Insulating Materials

  • Charge compensation system alignment – do users need to be taught how to adjust XY position and flux and when to adjust it?
  • Surface roughness affects FWHM and ease of XY alignment – smooth surfaces are much easier to control charging
  • What is the typical voltage used in charge compensation system?  (0.1, 1.0 or 5.0 eV)
  • Require seller to demonstrate how to align charge compensation system on a small piece of Poly-Propylene or HDPE
  • Ask for data from the edge and also the center of the sample.  Are results the same?  XY position of flood gun?
  • Charge compensation usually does not degrade surface chemistry but long term exposure to X-ray flux might

Key Factors that Define Throughput of Analyses

  • Stability of chemistry to X-ray flux and electron flux
  • Length of time used to collect data without significant degradation of chemistry
  • Rate of degradation of chemistry during short and long time data collection runs

Measure chemistry degradation of insulating materials that must be analyzed in your new XPS instrument

  • Measure chemical state spectra of C (1s), O (1s) and metal (X) using 5 scans and typical high resolution scan settings
  • Then measure survey spectrum of that sample using just 1 scan and normal survey spectrum settings.
  • Keep X-rays and Flood Gun turned on.  Wait 30 minutes, and then repeat those same spectra.
  • Compare the results.  Make overlay using same CPS not counts.  Look for changes in Peakshapes and atom%

Sample Physical Changes that might Occur during XPS Analysis

  • Caused by vacuum removing water from wet sample during analysis
  • Caused by vacuum removing solvent from wet sample during analysis
  • Caused by vacuum removing gases trapped on surface of powder during analysis
  • Polymer surface structure can re-arrange due to loss of solvent

Sample Chemistry Degradation during XPS Analysis

  • Excessive flux can cause changes in oxidation states for highly oxidized compounds 
  • Excessive flux can cause polymers to lose Cl, F, Br, I as HCl, HF, HBr, HI gases forming double bonds
  • Excessive flux can cause polymers to lose CO or CO2 as gases
  • Excessive flux can cause carbonates to lose CO2 as gas
  • Aromatic groups and nitriles (CN) tend to stabilize polymers

Where will the instrument be installed?

  • A basement might be a source of high humidity
  • A top floor might cause vibrations that affect imaging and small spot analyses
  • Is there a source of strong magnetic fields nearby (NMR, MS, ICP-MS)
  • Is there a train line nearby that produces magnetic field flux
  • Is there enough space between the wall and the back of the instrument for service engineer to work
  • Is there a good earth ground nearby

Condition of System Failure Requiring Return and Refund

  • Instrument dropped during shipment under maker’s control
  • Instrument fails to meet minimum specification
  • Delivery does not include all parts ordered
  • Instrument specifications not met within 2 months of on-site installation

Instrument Makers

  • Which companies produce fully integrated XPS systems designed to provide optimized XPS performance?
  • Which companies produced special vacuum systems with XPS as an attachment that focus on vacuum system?
  • XPS systems are sold in many countries by local distributors.

Money Sources

  • Grant money from government offices
  • Department money from large companies
  • Money from banks as a small business loan

Why are you buying a new XPS instrument?

  • A new research project needs a modern XPS.
  • The old XPS instrument can no longer be repaired.
  • The old XPS uses non-mono X-rays and produces heat (>120 C) that degrades surface chemistry.
  • The old XPS uses non-mono X-rays that give poor energy resolution making it difficult to resolve chemical states.
  • Production needs an XPS for development, QC and QA.
  • IT can no longer support the old computer and old operating system.
  • The number of samples for analysis has increased by 200%.
  • Automated analyses are needed to serve the needs of a large number of users.
  • Advancements in data processing greatly improve results and interpretations.
  • Multiple analysis methods are available on one instrument.
  • Angle resolve and sample rotation and sample heating are available.

Maintenance Costs

  • Reputation for service by maker
  • Number of servicemen available nearby to service your instruments
  • Does maker provide support by remote control over internet
  • Cost per hour for service engineer to travel to your site
  • Cost per hour for service engineer to work at your site

Lifetime of Detectors and Filament

  • Typical lifetime of ion gun filament for most users
  • Typical lifetime of X-ray gun filament for most users
  • Typical lifetime of electron detector for most users
  • Predicted (expected) lifetime of ion gun filament 
  • Predicted (expected) lifetime of X-ray gun filament based on 1,000 hr of use
  • Predicted (expected) lifetime of electron detector based on 1,000 hr of use

Lifetime of Turbo-pumps, scroll pump, TSP filaments and water chiller

  • Typical lifetime of turbo-pump
  • Typical lifetime of scroll pump
  • Typical lifetime of 1 set of TSP filaments
  • Typical lifetime of water chiller

Instrument Down-Time Planning

  • If instrument will be down one month, what happens?
  • When instrument is down, can another lab help?
  • Who is blamed if instrument stays down many months?
  • How many groups are using the same instrument?

Who will be responsible for Instrument Maintenance?

  • Professor
  • Graduate student
  • Group engineer
  • Instrument facility’s manager
  • Scientist
  • Group manager

Samples:  What percentage, %, of your samples are?

  • Insulators that need good charge control?
  • Thin films that need depth profiling?
  • Semi-conductors that need reliable BEs?
  • Materials that need reliable atom % results?
  • Can be degraded by excess X-ray flux or electron flux?
  • Materials needing 1-2 um spatial resolution imaging?
  • Materials needing small 10-20 um point size analyses?
  • Powders or fibers?
  • Too large to fit inside the old XPS system?
  • What are the real XYZ dimensions of the tallest sample that can be analyzed? 

Wants:  New capabilities, accessories, and features? 

  • AR-XPS 
  • Small spot
  • Auto-focus
  • Size of sample stage
  • Limit of sample size
  • Ion Gun (mono-atomic Argon ions)
  • Gas Cluster Ion System (using large clusters of low voltage Argon Ions)
  • Hot stage
  • Cold stage
  • Large sample size
  • Sample storage under UHV
  • Instrument baking
  • Vacuum transfer vessel
  • Extra sample stages for different groups
  • Sample recovery if sample dropped inside
  • Advanced data processing software
  • Data exchange – ASCII, VAMAS, ISO export and import

Software Features

  • Sensitivity factors used?  (Wagner, Scofield, PHI, CasaXPS, home-made?) Reliable?
  • Automated AR-XPS stage software
  • Automated XYZ imaging or mapping software
  • TFA
  • NLLSF
  • Real-time imaging and count-rate of live XPS signal
  • Multi-phase control of depth profiling software

Training Videos and Manuals

  • Videos showing how to operate Software
  • UV source operation and UV data processing
  • ISS source operation and ISS data processing
  • AR-XPS operation and data processing manual
  • Advanced data processing feature and how to operate with Video and manual

Who can or will supply and install Spare Parts and Vacuum Supplies

  • Oil
  • Scroll pump seals
  • Copper gaskets
  • Rubber O-ring gaskets
  • Dry scroll pump

What is the potential future research or QC use of this new XPS instrument?

  • Does the new research use solid materials or outgassing powders.
  • Who will train the new users?
  • Will new group pay for a share of maintenance 
  • Does the new group need to buy a new instrument

Replacement Cost of Electronic Boards, Filaments, Anodes, Filters

  • Cost of replacement boards for ion gun, detector, flood gun, X-ray gun
  • Cost of replacing detector itself
  • Cost of replacing vacuum filaments
  • Cost of standalone processing software for many users
  • Cost of extra sample stages for different groups to use
  • Cost of repairing dry scroll pump

Service Contract Cost

  • Trained service engineer on site within 36 hours cost?
  • Trained service engineer on site within 72 hours cost?
  • Discount per hour when service engineer is late?
  • Cost of yearly preventive maintenance (PM) kit and what is included in kit

Instrument Performance Check after Service is Completed

  • After repair is completed, will installer provide proof of repair without charging hourly rate?
  • After new ion gun filament is installed, will installer test ion gun etch rate and demonstrate alignment using SiO2 etch crater?
  • After new X-ray anode is installed, will installer provide proof to meet specification for largest and smallest spot size count rates and alignment?
  • After new detector is installed will installer provide proof of instrument specification?

Installation Needs 

  • Electricity voltage, phases, transformer
  • Water supply
  • Compressed dry air supply
  • Nitrogen gas supply
  • Argon gas supply
  • Multiple gas regulators for Ar, N2, He, air 
  • Stainless steel tubing for Argon gas line
  • Lift truck for instrument transfer
  • Hallway width
  • Door removal needed

Sample Preparation Bench and Tools

  • Tweezers
  • Spatulas
  • Mortar and Pestle
  • Magnifying glasses
  • Camera (USB)
  • Hammer to break large materials
  • Glass cutters
  • Carbide tipped scribes

Special Sample Preparation Equipment

  • Small vacuum oven with Teflon seal (not silicone)
  • Distillation system for clean IPA
  • Plasma cleaning system
  • Ozone cleaning system
  • Static discharge system
  • Storage dry box
  • Small clean oven with disposable foil liners

Demonstration Results

  • Quality of data received by mail versus time actually used to collect data
  • Quality of live demonstration
  • Was Demonstration Engineer a high level expert
  • Actual spectra from YOUR insulating powders and rough surfaces 

List of Options than can be added before Delivery

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List of Options that can not be added after Delivery

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