Abstract: A method for producing a resist structure on a semiconductor material which has an opening tapering towards the semiconductor material is provided. This method can be used, for example, for the manufacturing of T-gate metallizations in a field effect transistor. In this method, a thin, upper resist layer is structured, and the structure is transferred onto a silicon nitride layer. The structure is then transferred into a thickly applied resist while widening the upper part of the etching profile. The method is accomplished by a succession of anisotropic and isotropic dry etching steps.

Abstract: The apparatus includes a means for generating a magnetic field at a first electrode to which a high frequency voltage is applied and includes a generator for generating a rectangular low frequency voltage that is capacitively coupled to a second electrode which carries the substrate to be etched. The low frequency voltage comprises a negative half-wave having a short duration and a positive half-wave. The duration of the negative half-wave is selected to be shorter than a time constant for charging the substrate after a potential change corresponding to the amplitude of the half-wave and the positive half-wave is dimensioned so that the substrate remains free of charges on the average.