The success story of electron beam lithography began in the 1980th with the development of the first PMMA resists. These resists are absolutely light-insensitive in the UV-wavelength range above 300 nm. Clean rooms in which e-beam lithography is performed with PMMA resists require therefore no yellow light.
We have already frequently been asked by e-beam users to also provide negative-tone resists which can be processed under white light conditions. Our negative e-beam resists of the series 7500 – 7700 are all also sensitive in the broadband UV (300 – 405 nm).
These resists are thus well suited for mix&match technologies (e-beam- and UV-lithography in a single process), but absolutely require yellow light. Employing new acid generators which are characterized by a UV-absorption < 280 nm, we developed the chemically enhanced e-beam resist SX AR-N 7700/46 which can also be processed under daylight conditions.
Wafers coated with SX AR-N 7700/46 were openly placed in a white-light lab for several hours and then exposed and developed together with resist-coated wafers not subjected to daylight conditions before. Sensitivity and gradation were identical in both test series.