Electron beam lithography is a very popular technique to produce structures with submicrometric dimensions, specially for studying advanced devices like GaAs based FETs or quantum devices. A scanning electron microscope (SEM) was adapted for this purpose. Or first attempts to produce such devices exploring the high resolution capabilities of the SEM were successful. Exposures for design with high level of integration should present problems like proximity effects, that arises from the electron backscattered from the resist/semiconductor interface. Corrections to this kind of problem is done through a numerical simulation of the electron-matter interaction process (a Monte Carlo – like simulation). This kind of simulation anticipates the energy density distribution profile dissipated through the resist and corrects ir to get a profile that fits to the best development results. These simulations wee used to develop a lift-off process with a bilayer PMMA resist (two different molecular weight) obtained in house.
