Abstract: A method of planarizing a semiconductor layer by use of a plasma etch step which also etches vias having a tapered profile is made possible by selecting a conformal layer preferably of a different material than the material through which the via is to be provided such that a plasma etch will establish differing etch rates in the conformal and underlying layers.

Abstract: Photoresist apertures having tapered sidewalls can be provided by first opening the aperture in accordance with ordinary practice followed by the exposure of the photoresist to a suitable energy source such as a flood exposure to wideband light, the heating of the photoresist to round the peripheral edges of the aperture and the exposure of the thus pretreated photoresist to an environment which removes photoresist from the inside wall of the aperture until the desired tapered profile is obtained. In the preferred practice of the invention, the pretreated photoresist is removed from the inside wall of the aperture through exposure to a dry oxygen plasma etch.