Comparison of different x-ray sources using the same printing process parameters

Abstract

The x-ray printing performance of a conventional electron bombardment source , a plasma focus source, and a synchrotron radiation source are compared. The same mask, resist process, and gap between mask and wafer are employed for all sources. A step-and-repeat x-ray mask aligner holds both mask and wafer in ambient atmospere so that the radiation travels through 1 mm of air. Both point sources—a stationary W anode source, and a plasma focus source using Ne gas—emit their radiation from a 1 mm diam spot at a 40-cm distance from the mask. This geometry is chosen to allow high resolution image transfer. The BESSY electron storge ring in Berlin is used as the synchrotron radiation source providing nearly parallel exposure light. All exposure sources emit their radeation at about the same wavelength , i.e., between 7 and 12 Å. Differences in imaging quality and exposure times will be discussed based on prints typically performed at a 40-μm gap in poly(methylisopropylphenylketone) (PMMA). The masks employed use a 1 μm gold absorber pattern on a silicon wafer thinned to 2-μm thickness. In future x-ray technology, the choice of the source may be related to the application. Depending heavily on throughput considerations all three sources might have a place in this promising technique.