Core level photoelectron microscopy with synchrotron radiation (invited)

The capabilities of a direct imaging photoelectron microscope (MicroESCA from Surface Science Instruments) have been demonstrated in a set of experiments carried out at the Stanford Synchrotron Radiation Laboratory (SSRL) using a torroidal grating monochromator in the photon energy range 20–170 eV. Photoelectrons from a 300×300 μm2 sample area are projected in the diverging magnetic field of a superconducting solenoid and an image reflecting the variation in photoelectron yield is recorded digitally with a resistive anode imaging detector. Lateral resolution is better than 5 μm. A retarding field analyzer located in front of the imaging detector acts as a high-pass filter and allows us to obtain a series of spectrally resolved images which can be processed to give a spot XPS analysis of areas as small as 5×5 μm2. Images from a sample of patterned aluminum on silicon are presented to demonstrate the potential of the instrument.