Carbonaceous contamination growth induced by resist outgassing under e-beam exposure

The emerging lithography tools with large numbers of parallel electron beams and direct-write capabilities provide an alternative solution to achieve high-resolution and high-throughput lithography for advanced CMOS nodes [Pain et al., C. R. Acad. Sci., Ser. IIB 7, 910 (2006); de Boer et al., Proc. SPIE 8680, 86800O (2013)]. However, resist outgassing during exposure induces carbonaceous contamination of the optics projection systems. This contamination is a major issue, much more than in classical electron-beam lithography, as the outgassing level is much higher. Thus, it is crucial to study both the outgassing phenomena and the associated contamination growth mechanisms, to assess resist platforms and define realistic specifications in order to limit their impact on the exposure systems. A specific experimental setup has been designed at Leti to perform 5-keV electron bombardment of e-beam resist-coated 100-mm silicon wafers. The setup allows two different configurations: an outgassing measurement mode ...