High-brightness ion source for ion projection lithography

A Penning-type surface plasma source has been developed with the goal to achieve the beam requirements for ion projection lithography (IPL). The present source, with simple, forced air cooling runs up to a duty factor of 1% (pulse length of 1 ms and repetition rate of 10 Hz); a cw Penning source is being planned for IPL. H- emission current density of more than 2 A/cm(2) has been obtained with negligibly low noise. The perpendicular temperature is about 0.6 eV for emission current density of about 1 A/cm(2)-this yields normalized beam brightness of more than 10(12) A/(mrad)(2). The energy spread full width at half-maximum (FWHM) for a 5 kV beam with angular current density of 33 mA/sr is about 3.3 eV (close to instrumental resolution). The energy spread increases with beam intensity. In preliminary experiments on positive ion extraction, noiseless H+ beams with emission current density of about 150 mA/cm(2) have been achieved. (C) 1996 American Vacuum Society.