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State of the art of pattern placement accuracy of silicon X-ray master masks

: Pongratz, S.; Mescheder, U.; Ehrlich, C.; Huber, H.-L.; Kohlmann, K.; Windbracke, W.

Microelectronic engineering 9 (1989), Nr.1-4, S.117-120
ISSN: 0167-9317
International Conference on Microlithography: Microcircuit Engineering (ME) <14, 1988, Wien>
Fraunhofer ISIT ()
elemental semiconductors; masks; silicon; X-ray lithography

A further increase in the integration density of SRAM and DRAM memories will be limited by resolution as well as overlay accuracy. In the case of synchrotron-based X-ray lithography, the main contribution to the total overlay budget is given by the achievable accuracy of the X-ray masks. In this paper, the pattern placement accuracy of silicon X-ray master masks will be shown, which are fabricated for real device application. The measurement results are obtained with an optimized and improved e-beam measurement system and discussed in terms of linear and nonlinear pattern placement errors. Considering a number of X-ray master masks with different absorber coverage within the step and repeat field (3*3 cm2) and different levels of complexity, the average pattern placement error including both statistical and linear contributions can be reduced reproducibly down to about 70 nm, including the principal accuracy of the e-beam pattern generator and measurement system.