A technique for determining local silicon resistivity from the measured spreading resistance associated with a metal to semiconductor, small‐area pressure contact is described. The major problems encountered in earlier attempts to derive quantitative resistivity data from small area pressure contacts on silicon have been circumvented by making the measurements at bias levels of a few millivolts and by using a particular osmium‐tipped probe arrangement to provide contact reproducibility. The method provides a three‐dimensional spatial resolution in resistivity measurements on silicon on the order of 1μ, and, using a calibration curve determined for a particular silicon surface finish, yields an experimental reproducibility ≤15% for sample resistivities in the range 10−3 normalohm‐normalcm≤ρ≤500 normalohm‐normalcm . Several examples of the application of the technique to problems of current interest in silicon technology are given.

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The extent of small‐scale radial resistivity inhomogeneity in several n‐type silicon crystals has been quantitatively determined with high spatial resolution by the spreading resistance resistivity measurement technique. Typical results for Czochralski, float‐zone refined, crucible‐less, web‐grown and vapor‐deposited epitaxial silicon are given, showing that appreciable nonuniformity in local resistivity exists in many crystals. The usefulness of the spreading resistance technique in rapid evaluation of the degree of resistivity inhomogeneity of individual silicon samples is illustrated.

It has been noticed that for ultrashallow ion implanted dopant profiles, the metallurgical junction is not at the same location as the peak of the spreading resistance profile, i.e., the on-bevel junction. This can be attributed to the carrier redistribution effect. Furthermore, the pressure under the spreading resistance probes causes band-gap narrowing of the material under the probes. This pressure-induced band-gap narrowing effect increases the intrinsic carrier concentration of the semiconductor material. An inverse algorithm used to convert spreading resistance profiles into the electrically active dopant profiles, taking both carrier redistribution and band-gap narrowing into account, is presented in this article. Using this algorithm, the depth of the metallurgical junction of a shallow ion implanted p ϩ n profile is determined to be 0.121 m from the surface, whereas the on-bevel junction depth is 0.089 m. The recovered dopant concentration profile agrees very well with that obtained from secondary ion mass sepctrometry. The algorithm is shown to work very well also for an n ϩ p junction.

An accurate method to measure the four point probe (4PP) sheet resistance (R s ) of USJ Source-Drain structures is described. The new method utilizes Elastic Material probes (EMprobe) to form non-penetrating contacts to the silicon surface. The probe design is kinematic and the force is controlled to ensure elastic deformation of the probe material. The probe material is selected so that large direct tunneling currents can flow through the native oxide thereby forming a low impedance contact. Sheet resistance measurements on USJ implanted P+/N structures with SIMS junction depths as shallow as 15 nm have been measured. The sheet resistance values obtained with the new EM-probe 4PP method were found to be consistent with expectations. In this paper, the method will be demonstrated on a variety of implanted USJ structures.