Importance

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Abstract

The present invention comprises forming a first conductive layer over the substrate to have a gap. A dielectric layer is then formed on the first conductive layer. A portion of the dielectric layer is removed to leave a residual dielectric layer in the gap. Next, isotropical etching is performed to etch the first conductive layer using the residual dielectric as an etching mask, thereby forming a conductive tip. A polishing stopper composed of oxide is formed over the conductive tip. A nitride layer is formed over the conductive tip and on the polishing stopper. The nitride is polished to the surface of the polishing stopper. A portion of the nitride layer is etched to form a step over the conductive tip. A second conductive layer is formed over the etched nitride layer. A portion of the second conductive layer is removed to expose an upper surface of the step. The nitride layer and the polishing stopper are respectively removed to expose the conductive tip.

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First Claim