X-RAY PHOTO-ELECTRON SPECTROMETRY

Instrumentation Description

 The three instruments that will be demonstrated in the Applied Surface Analysis Workshop at the Swagelok Center for Surface Analysis are described below:

The PHI 680 Auger Nanoprobe consists of a field-emission scanning electron microscope with a Schottky emission cathode, a secondary electron detector, and an axial cylindrical mirror analyzer with a multi-channel detector to collect Auger electrons produced during electron irradiation. Very small spot sizes can be realized with this instrument -down to 7 nm. This is useful for high-resolution imaging and for Auger data acquisition using low beam currents. Inert gas sputtering (using a PHI 06-350 ion gun) is used to clean surface contamination from samples and to remove material from a small area on the surface for depth profiling. Several modes of operation are available to the user, including survey, line, profile, and elemental mapping. Capable of multi-point analysis, the instrument is a powerful tool for routine failure analysis and quality control of inorganic samples. An additional device permits in situ fracture of samples, at liquid nitrogen temperature if necessary.

The PHI VersaProbe XPS Microprobe is a multi-technique surface analysis instrument based on PHI's highly developed scanning X-ray microprobe technology. The most important advantage of this instrument is that the VersaProbe can produce a focused, highly monochromatic X-ray beam that can be scanned over the specimen surface. In this instrument, a point source of X-rays is created by focusing an electron beam onto an Al anode. A monochromator, consisting of an ellipsoid-shaped crystal, collects X-rays from the point source and focuses them on the surface of the specimen. The focused X-ray beam can be scanned across the specimen surface by correspondingly scanning the electron beam across the surface of aluminum anode. A major advantage of this design is that most of the photoelectrons generated by the focused X-ray beam are actually collected by the electron energy analyzer, whereas in the conventional design, most of the photoelectrons are lost. With the VersaProbe, the spot size can be varied between less than 10 μm diameter (for highest spatial resolution) to 100 μm (for highest sensitivity). The field of view can be as large as 1500 μm by 1500 μm.

The PHI TRIFT V nanoTOF instrument is the latest generation of PHI's surface analysis line of TOF-SIMS instruments, utilizing a newly developed, high-quality "TRIFT" analyzer.  It is equipped with an Au, a C60, and an Ar gun. An innovative new sample handling platform enables analysis of samples with complex geometries. In addition, the system has state-of-the-art charge compensation and ion gun performance.  Time-of-flight secondary-ion mass spectrometry (TOF-SIMS) provides sub-micrometer elemental, chemical, and molecular characterization and imaging of solid surfaces. Different from D-SIMS ("dynamic" SIMS), this technique enables analyzing the outermost one or two mono-layers of a sample while basically preserving molecular information. While D-SIMS provides primarily elemental information, TOF-SIMS surface analysis yields chemical and molecular information. TOF-SIMS is ideal for both organic ond inorganic materials, and can be used to characterize both insulating and conductive samples. With detection limits in the ppm to ppb range, shallow depth profiling capabilities and automated analysis, the nanoTOF can be used to study surface contamination, trace impurities, thin films, delamination failures etc. It is also a valuable tool to investigate surface modification chemistry and catalyst surface composition.