A multilayer resist system is used to obtain high‐definition and high aspect ratio masks by use of electron lithography. This technique overcomes most of the problems of obtaining with a short exposure time a high‐definition mask: a lift‐off metal deposition is made over a tick bilayer of hard‐baked resist which is then patterned by reactive ion etching in pure low‐pressure oxygen plasma. This inverted multilayer system can be used for dry etching of many different material sublayers and can be easily stripped away in a dedicated solvent after the etching. An example of application in self‐aligned structures is given.