E-beam direct write lithography: the versatile ally of optical lithography

Electron Beam Direct Write (EBDW or E-Beam) Lithography is a worldwide reference technology used in laboratories, universities and pilot line facilities for Research and Developments. Due to its low writing speed, E-Beam direct write has never been recognized as an acceptable industrial solution, exception made for optical mask manufacturing. Nevertheless, its natural high-resolution capability allows low-cost patterning of advanced or innovative devices ahead of their high-volume manufacturing ramp-up. Thanks to its full versatility with almost all type of chemically amplified resists, EBDW is a perfect complementary solution to optical lithography. This paper demonstrates the compatibility of EBDW lithography with advanced Negative Tone Development (NTD) resist and the possibility to set-up an hybrid E-Beam/193i lithography process flow with high performances in terms of resolution and mix & match overlay. This high-end lithography strategy alliance offers flexibility and cost advantages for device development R&D but also powerful possibilities for specific applications such circuit encryption as discussed at the end of this work-study.