Abstract: In the fabrication of semiconductor devices it has been found useful to employ plasma etching to create contact holes in the insulating layers that cover the wafers being processed. In particular, when wafers are being fabricated that employ small diameter contacts, it is difficult to ensure that all contact holes are created simultaneously. If etching is continued sufficiently to make sure that all of the contact holes over the wafer are fully etched, it is found that a certain proportion are overetched. If the silicon semiconductor is converted to a metal silicide in the region where contact is to be made subsequently, its plasma etch rate can be reduced sufficiently to avoid overetching.

Abstract: A method of fabricating a high-frequency bipolar transistor structure wherein the emitter, higher impurity concentration base, and lower impurity concentration base regions are defined in a single masking operation. Permeation etching is used to etch regions of an oxide layer under a layer of resist which defines regions of the higher impurity concentration thereby simultaneously defining the emitter and lower impurity concentration base regions. The higher impurity concentration base regions are formed by ion implantation of impurities through the unetched oxide regions. The resist is then removed and the lower impurity concentration base and emitters are formed through the resulting opening in the oxide. This results in the self-aligning of the emitter regions with respect to the base regions.