Preparation of a Lightly Loaded, Close-Spaced Spreading Resistance Probe and its Application to the Measurement of Doping Profiles in Silicon

A commercially available spreading resistance probe, the ASR-100, was modified to operate with lighter probe loading and smaller probe spacing. The advantages of device structure profiling, increased resolution, and reduction in the “correction factor” in the converted impurity concentration profile are realizable with smaller probe spacing. The effect of the probe modifications on sample profiles and profile quality is discussed for thin epitaxial layers, bipolar transistor structures, and ion-implanted layers. Sample preparation, as influenced by the beveling technique, is also shown to have an effect on profile quality. A novel method for precise measurement of very small bevel angles is described.