Recently, in order to print patterns of ultra large scale integrated circuits, the demand for soft X-ray sources has become greater. A high current vacuum spark has a merit of flexibility in selection of characteristic X-ray emission wavelengths, because many materials can be used. This paper proposes use of sulfur as an X-ray material from the viewpoint of pattern contrast. Sulfur characteristic X-rays (0.4-0.52nm) offer a range of suitable soft X-rays for various mask materials, i. e. tantalum, tungsten, platinum and gold. In experiments, sulfur was put in a PTFE pipe which was set in the center of the anode. Soft X-ray emissions resulted when a pulse current of about 150kA flowed. The X-ray emission time from discharge to production of a magnetic pinch was about 1μs at various discharge currents. This time was short in comparison with the 2.4μs rise time of the discharge current. Therefore the X-ray intensity should be enhanced by utilizing a fast rise time current.
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