The Plasma Focus As Soft X-Ray Source For Microscopy And Lithography

Abstract

Plaafocs devices producing small volume of plasma with electron density n_e ≈ 10²⁰ cm^-3 and mean particle energy of about 1 keV seem to meet the requirements for compact X-ray sources for industrial use. Their emission properties can be taylored for X-ray microscopy where narrowband emission with high spectral brilliance in the water window (2.4 nm to 4.3 nm) is required, as well as for X-ray lithography demanding for high mean power in the wavelength region from 0.7 nm to 1.0 nm. For X-ray microscopy the emission of Lyman-a lines is of advantage whereas for X-ray lithography the broadband continuum and line radiation can be used. For X-ray microscopy a single pulse source using the is - 2p line of nitrogen VII at 2.48 nm and for X-ray lithography a source running with several Hz repetition rate using the emission of hydrogen- and heliumlike neon ions around 1 nm are being developed.