X-RAY-LITHOGRAPHY USING WIGGLER AND UNDULATOR SYNCHROTRON RADIATION SOURCES

Wiggler and undulator insertion devices are very powerful sources which allow new approaches in the design of synchrotron x-ray lithogra-phy systems. The principal advantage of insertion devices is that they can be used as narrow bandwidth high throughput lithography sources at any wavelength. For a wiggler the increased flux can be continuously traded off against beam current, horizontal beam angle and bandwidth. The undulator offers several watts of power in a narrow 1% bandwidth and has a very compact beam (0.05 mr) which must be scanned both horizontally and vertically. Insertion devices could thus be used in an evolutionary way with conventional x-ray tube technologies or in a revo-lutionary way at high contrast very soft x-ray wavelengths. A systems design approach is used to identify feasible options for wiggler and undulator beam lines for x-ray lithography in the 0.5-0.2 11,μm linewidth region over 5 cm by 5 cm fields. Typical parameters from the Wiggler and Undulator in the Advanced Light Source designed at the Lawrence Berkeley Laboratory are used as examples. Moving from the conventional wavelengths of 4-9 A to very soft wavelengths around 15 A is shown to be very promising. The mask absorber thickness can be reduced a factor of three so that 0.2 Am features can be made with a 1:1 mask aspect ratio. The mask heating rnited exposure time is also reduced a factor of three to 3 sec/cm . However, extremely thin beam line windows (1/4 mil Be) and mask supports (1 Am Si) must be used. A wiggler beam line design using a small slit window at a scanning mirror appears feasible. A unconventional, windowless differentially pumped beam line with dual deflecting mirrors could be used with an undulator source.