A plasma x-ray source for x-ray lithography

Abstract

Employing a gas-‘‘puff’’ z-pinch plasma, a high brightness and compact plasma x-ray source has been constructed by using a high-repetition-rate discharge and a new x-ray extraction method. The high-repetition-rate discharge (3 Hz) is attained by using a fast-acting gas valve, capable of operating stably under gas plenum pressures below 300 Torr. This low gas pressure discharge makes possible high-conversion efficiency of electrical input to x-rays, highly reliable plasma pinching, and a drastic reduction of debris resulting from electrode vaporization. An axial x-ray exposure is required to reduce the blur in pattern replication caused by the penumbral effect. To carry out the axial exposure, the high-energy particles emitted from the plasma are removed using a plasma reflector plate and magnet. The x rays are efficiently extracted through a window highly transparent to x rays. With this x-ray source, 9–14 Å x rays with 200 J per pulse (600 W average power) are obtained using Ne gas plasma in a 3 Hz operation.