All-inverter complementary metal oxide semiconductor based dose control circuit for using vertically aligned carbon nanofibers in maskless lithography

This article presents a prototype implementation of a circuit that can control charge emission from the vertically aligned carbon nanofibers (VACNFs), for use in the implementation of digital electrostatically focused e-beam array direct-write lithography. This lithography technique can be used to fabricate ultra-small feature size devices, while cutting down the manufacturing costs of photomasks [Baylor, J. Vac. Sci. Technol. B 20, 2646 (2002)]. These VACNFs are found to be quite robust for use as microfabricated field-emission devices [Bolton, Sens. Actuators B 85, 179 (2002)]. The all-inverter based dose control circuit presented in this article was fabricated using a standard 0.5 μm complementary metal oxide semiconductor process to improve the dose-rate accuracy, when using these VACNFs for etching in maskless lithography. Simulation and measurement results are compared and analyzed, and future work for improving the design is discussed.