IMPROVED (RIE) PLASMA ETCH PROCESS FOR MAKING METAL-SEMICONDUCTOR OHMIC TYPE CONTACTS

Described is an improved process of RIE plasma attack of the layer of dielectric material on the surface of wafers of semiconductor material, in correspondence of areas purposely defined by masking, for exposing the underlying semiconductor crystal, in preparation to depositing a layer of material of metallic conduction. After having provided to remove a certain thickness of dielectric according to the known technique, the conditions of attack are modified, substituting the plasma gases and reducing the "bias" and attack is resumed of the residual layer of dielectric and preferably also of a certain thickness of the semiconductor crystal in the same reactor. Ohmic contacts with relatively low contact resistance and great reliability are obtained with a minimum handling of the wafers.