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XPS (ESCA)

pic38Description:Thermo-VG Scientific ESCALab 250 Microprobe

XPS is also known as ESCA, an abbreviation for “electron spectroscopy for chemical analysis” introduced by Kai Siegbahn and his research group.

Detection limits for most of the elements are in the parts per thousand range (1,000 PPM). Detection limits of parts per million (ppm) are possible, but require special conditions: concentration at top surface or very long collection time (5 hr). The most basic ESCA analysis of a surface will provide information elemental composition, empirical formula, chemical state and electronic state of the elements that exist (except H and He)., making it a fabulous product testing and quality assurance tool for manufacturers of polymers, medical devices, electronics, and more. XPS spectra are obtained by irradiating a material with a beam of X-rays while simultaneously measuring the kinetic energy and number of electrons that escape from the top 1 to 12 nm of the material being analyzed. XPS requires ultra-high vacuum (UHV) conditions.

Application:

XPS is routinely used to analyze inorganic compounds, metal alloys, semiconductors, polymers, elements, catalysts, glasses, ceramics, paints, papers, inks, woods, plant parts, make-up, teeth, bones, medical implants, bio-materials, viscous oils, glues, ion modified materials and many others.

Measure the very top surface chemistry (1-10 nm) of any material.

It is a surface analysis technique with a sampling volume that extends from the surface to a depth of approximately 50-100Å.

XPS is a surface chemical analysis technique that can be used to analyze the surface chemistry of a material in its’ “as received” state, or after some treatment, for example: fracturing, cutting or scraping in air or UHV to expose the bulk chemistry, ion beam etching to clean off some of the surface contamination, exposure to heat to study the changes due to heating, exposure to reactive gases or solutions, exposure to ion beam implant, exposure to ultraviolet light.

Surface analysis of organic and inorganic materials, stains, or residues

Determining composition and chemical state information from surfaces

Depth profiling for thin film composition

Thin film oxide thickness measurements (SiO2, Al2O3)

XPS can measure:

  • elemental composition of the surface (top 1–10 nm usually)
  • empirical formula of pure materials
  • elements that contaminate a surface
  • chemical or electronic state of each element in the surface
  • uniformity of elemental composition across the top surface (or line profilingor mapping)
  • uniformity of elemental composition as a function of ion beam etching (ordepth profiling)
  • Metallurgy
  • Grain Boundary Segregation
  • Electronic structure of metallic alloys
  • Surface engineering
  • Ceramic and Catalyses
  • Corrosion science
  • Microelectronic and semiconductor materials
  • Polymeric material
  • Adhesion science
  • Medical device manufacturing
  • Identifying stains and discolorations
  • Characterizing cleaning processes
  • Analyzing the composition of powders and debris
  • Determining contaminant sources
  • Examining polymer functionality before and after processing to identify and quantify surface changes
  • Obtaining depth profiles of thin film stacks (both conducting and non-conducting) for matrix level constituents and contaminants (down to the low % level)
  • Assessing the differences in oxide thickness between samples
  • Measuring lubricant thickness on hard disks

Specification

  • Signal Detected: Photoelectrons from near surface atoms
  • Elements Detected: Li-U Chemical bonding information
  • Detection Limits: 0.01 – 1 at% sub-monolayer
  • Depth Resolution: 20 – 200Å (Profiling Mode); 10 – 100Å (Surface analysis)
  • Imaging/Mapping: Yes
  • Lateral Resolution/Probe Size: 10 µm – 2 mm