A RADIATION SOURCE FOR X-RAY-LITHOGRAPHY

The vast majority of x-ray lithography efforts are presently using electron storage rings as an x-ray light source. These sources offer a unique combination of high brightness and good beam collimation. High brightness is required for future mass production of semiconductor devices, good light collimation is required for good mask-to-mask overlay especially on large step fields. Point sources can supplement work at synchrotron beamlines or can serve as an x-ray lithography entry tool if the spectrum is similar to synchrotron radiation and if sufficient beam collimation is provided. The latter is only possible at the expense of throughput. The plasma focus source described here meets these requirements of synchrotron compatibility. The broadband continuum radiation is centered around 0.9 nm. The degree of beam collimation used allows the use of large exposure windows envisioned for mass production. Using a high resolution Si/Au mask 200 nm features printed at a 40-mu-m gap in 1-mu-m thick Novolak-type photoresist have been obtained.