Pulsed Plasma Source For X-Ray Lithography

A compact, efficient, high-brightness pulsed plasma x-ray source has been demonstrated. The source has a conversion efficiency, from electrical input to usable x-ray energy, of greater than one percent. X rays are emitted from a cylindrical volume approximately 1 mm in diameter and 10-mm long. Various wavelengths can be obtained by the choice of appro-priate plasma materials. Submicrometer features have been replicated using x-rays in the 12 A region to expose a wafer, coated with FBM resist (~ 50X PMMA sensitivity), through a polyimide/gold x-ray mask. The exposure was made through a 25-μm-thick beryllium filter with the wafer 30 cm from the source. Twenty x-ray pulses were required to fully expose the resist. For this experiment the available electrical pulse power supply was limited to one pulse every few minutes. However, the x-ray source itself is capable of much faster pulse rates, and electrical driver technology to power the x-ray source at one or more pulses per second is within present state-of-the-art.