Determination of Diffusion Characteristics Using Two- and Four-Point Probe Measurements

By the use of twoand four-point probe measurements, much can be learned about the characteristics of a doped silicon wafer. The two-point probe system (spreading resistance probe) will provide resistivity vs depth profiles while the four-point probe system will indicate the uniformity of the diffusion over the surface of the wafer. Both systems have the same equation as their basis. The development of each system from this equation is discussed. Applications and the strengths and weaknesses of each system are discussed.