Solenoid gas puff imploding liner x-ray source

Abstract

There is a worldwide effort to produce a soft x-ray source for submicron microlithography to manufacture future generation large scale integrated microchips. The gas puff plasma discharge has been suggested as a viable alternative for low volume facilities which require relatively low throughputs with a single aligner station. The repetition rate for such systems is limited by the large gas flow into the vacuum system with the standard electromechanical puff valve. A unique puff arrangement is being developed which will limit the dead gas flow and, in principle, will allow for the development of high repetition rate systems. In this arrangement, the gas flows continuously from a low-pressure plenum through an annular aperture into the Z-pinch electrode gap. A discharge through a single turn solenoid coil mounted on the outside of the plenum inductively heats the gas, temporarily increasing the mass flow to produce a low mass (<1 μg), preionized liner which is imploded by a Z-pinch current discharge. (Multiturn coils have also been used. However, all the experiments reported in this paper used a single turn configuration.) Experiments were carried out with a variety of low-energy (<2.5 kJ) drivers including capacitor banks, peaking capacitors, and dc charged paper/castor oil Blumleins. Radiation measurements in the ultrasoft and soft x-ray regions were made using x-ray diodes, p-i-n diodes, and a time integrated pinhole camera. A slug model coupled to a capacitor bank or Blumlein circuit solver is used to estimate the liner dynamics as well as the load current and voltage.