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 pointfocused 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 µ m 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.

Laser-Plasma X-ray Sources Using Ceramic Target

“…The 13 nm X-ray emission from the line-focused pure-Al plasma has already been used for a photoelectron microscope. 13) We performed multiple shots irradiation experiments where the laser beam was focused on the same position of the target. The trends of the emission intensity of the Al XI, 15.47 nm, line are shown in Fig.…”