<title>Spherical pinch (soft x ray/EUV) and vacuum spark (soft x ray) for microlithography</title>

Abstract

Spherical pinch and vacuum spark have been pursued by Advanced Laser and Fusion Technology, Inc. for a number of years as candidates for point radiation source needed in microlithography. In the spherical pinch electrical energy is used to generate spherical imploding shock waves that compress a performed plasma into small (diameter < 1.0 mm) radiation source. The temperature of the central plasma can be high enough for emission of broadband radiation from the UV to the soft X-ray region of the spectrum. In the vacuum spark a small capacitor (a few nF) is discharged through two properly shaped electrodes in a vacuum. During the discharge 'hot spots' (minute high temperature plasmas) are formed in the vicinity of the anode and intense pulsed soft X-rays can be generated around the characteristic lines of the electrode materials. High rep-rate operation of the vacuum spark is necessary to provide sufficient dosage for microlithography.