One-layer technique for absorber structuring of E-beam written master masks for X-ray lithography

For high resolution pattering of X-ray master masks by e-beam lithography, it is state of the art to use an elaborate tri-level technique for the absorber structuring of critical mask layers. At present PMMA is used in this application as the e-beam sensitive top resist. In producing master masks of very high complexity, e.g. SRAM or DRAM devices, the relative low sensitivity of PMMA is causing considerably long writing times. To overcome this problem the newly developed negative-tone resist 'RAY-PN' with a sensitivity of about 20 times higher than PMMA has been used. Furthermore, a one-layer arrangement with this resist was investigated to reduce the number of process steps for absorber patterning of mask layers with CD down to 0.5 mu m.