The scanning tunneling microscope(STM) provides a confined low energyelectron beam which can be exploited for e‐beam lithography. It offers the potential of overcoming the resolution degradation due to secondary and backscattered electrons produced by the high energy primary beam in conventional e‐beam lithography systems. A polydiacetylene negative e‐beam resist has been evaluated in an STM mounted in a ultrahigh vacuum (UHV) chamber. The resist can be both imaged and exposed i n s i t u by the STM. Under e‐beam irradiation raised features are formed which can be imaged directly. A minimum feature size of 20 nm has been observed which is less than third of the minimum feature size observed following exposure in a high voltage e‐beam writer and development. The smallest features were written in the STM at an electron energy just above the exposure energy threshold which was measured to be about 8 eV.