Abstract
A high brightness, compact plasma x-ray source for x-ray lithography employing a gas-puff z-pinch plasma is developed. This source is designed to direct the x-ray downward into the atmosphere by connecting a diode with a condenser bank through a parallel transmission line and to easily link to a conventional aligner. High x-ray output power is attained by high-repetition-rate discharge (3Hz), developing a fast-acting gas valve. When pinched plasma is formed, the x-rays are emitted from the pinched columnar plasma region (20mm in length and 2mm in diameter). Axial x-ray exposure is achieved by a newly developed x-ray extraction method to reduce the blur in pattern replication caused by the penumbral effect. The x-rays are efficiently extracted through a window highly transparent to x-rays. With this x-ray source, 9-14 A x-rays with 200 J per pulse (600W average power) are obtained using Ne gas plasma in a 3Hz operation. The x-rays through x-ray extraction window (15-μm-thick Be) and x-ray mask (1-μm-thick SiN) have a peak intensity at 12 A wavelengths. The x-ray wavelength is longer than that of a conventional electron impact source. In addition, hard x-rays are not emitted by this plasma x-ray source. High contrast sufficient to replicate fine patterns can be obtained using a mask with a thin absorber, such as 0.4-μm-thick Ta. A 0.2μm resist pattern can be easily replicated.
