Dense plasma focus x-ray source for lithography

A point x-ray source for sub-micron lithography is under development, using a discharge driven, Dense Plasma Focus (DPF) in neon. The discharge is produced by a ≤ 4 kJ, ≤ 12 kV, capacitor bank circuit, which has a fixed inductance of 12 nH and drives ≤ 450 kA currents into the DPF load, with ∼ 1.1 μs rise-times. This paper will describe measurements of the x-ray output (10--20 J/pulse) the spot size (0.3--0.8 mm) and the spectrum (8--14 angstrom) of the DPF source. The dependence of these parameters on the DPF head geometry, bank energy and operating pressure will be discussed. The x-ray output has been measured using filtered pin diodes, x-ray diodes, absolutely calibrated x-ray crystal spectra and dosimetry masks. At a pulse repetition rate of 20 pps, this source should produce 200--400 W of x-ray power in the 8--14 angstrom wavelength band, with an input power of 40--60 kW. The suitability of such a source for 0.25 μm rule lithography will also be discussed