A method of lithography similar to electron-beam lithography except that the electron beam is replaced by a beam of ions. The ions are heavier than the electrons used in e-beam lithography and therefore suffer far less scattering within the resist and produce very few low-energy secondary electrons. They can also supply more energy to the resist, which results in greater resist sensitivity and reduced writing time. There are difficulties in producing collimated ion beams and with the effect of the ions on the semiconductor substrate below the resist layer. Multilevel resists are needed to eliminate the latter effect.