Process for improving the yield of integrated devices including schottky

Abstract

In the fabrication of Schottky barrier diodes, in conjunction with active devices such as transistors, it has become the conventional practice to use reactive ion etching (RIE) to remove a protective layer of Si.sub.3 N.sub.4. This step of etching is used in forming the anode regions of the Schottky barrier diodes, as well as the active device regions of the transistors. It has been discovered by the present inventors that 'resistive shorts' which have been produced in this context--thus ruining the Schottky barrier function--result from the fact that pinholes in the underlying oxide insulating layer permit the reactant gas to etch all the way down to the silicon substrate so as to produce diffusion paths or 'pipes' through the oxide. Accordingly, instead of the oxide layer acting to block diffusion in the Schottky anode areas, these diffusion paths permit the resistive shorts to be formed. The present invention involves the use of a low energy collimated ion beam in an inert atmosphere, e.g. argon gas, to selectively remove the protective layer. In so doing the ion beam removes the Si.sub.3 N.sub.4 without attacking any of the pinholes in the underlying oxide at the anode areas.