FOUR POINT PROBE MEASUREMENT

A basic property of a conductive material is its electrical resistivity. The electrical resistivity is determined by the availability of “free electrons” in the material. In turn the availability of free electrons is determined by the physical binding properties of the material on a molecular level. Other important properties of the material are related to the physical binding properties and therefore to the electrical resistivity of the material.

Much may be learned about the properties of a material by measuring its resistivity. An important example is the characterization of semiconductor materials where the resistivity is strongly related to the level of purposely added impurities. Measurement of the resistivity is used to both characterize the material and as a process control parameter for the semiconductor manufacturing process. Resistivity measurements are also used to characterize many other materials such as conductvice metal-based films, magnetic films used in CDs, III-V compound films, highly resistive...etc. Depending on the resistivity range, different equipment & instrumentation need to be used as shown below.