Development of Photoelectron Microscope with Compact X-Ray Source Generated by Line-Focused Laser Irradiation

Abstract

A laboratory-sized x-ray photoelectron microscope was constructed using a compact x-ray source produced by line-focused laser irradiation. The system is a scanning type photoelectron microscope in which the x-ray beam is micro-focused via Schwarzschild optics. A compact laser-plasma x-ray source has been developed consisting of a YAG laser, a line-focus lens assembly, an Al tape-target driver and a debris prevention system. The 13.1 nm x-rays were delivered from the line plasma whose length was 0.6 to 11 mm with higher intensity than that from a point-focused source. Schwarzschild optics having a designed demagnification of 224 and coated with Mo/Si multilayers for 13.1 nm x-rays, was set on the beamline at a distance 1 m from the source. The electron energy analyzer was a spherical capacitor analyzer with a photoelectron image detection system that was suited for detection of a burst of photoelectrons excited by pulsed x-rays of ns-order duration. Photoelectron spectra were obtained having two peaks from As 3d and Ga 3d electrons, when a GaAs wafer was used as a sample. Spatial resolution of less than 5˜3 μm was confirmed from the variation of the As 3d electron intensity along the position of the GaAs sample coated with a photo-resist test pattern.