Spreading resistance analysis based on the method of regularisation

Abstract

The method of regularisation is applied to recover, from spreading resistance (SR) measurement data, the dopant profiles of a variety of pn junction structures in which carrier spilling effects are significant. These structures range from those of several microns thick to submicron structures. A comparison is made of two methods of deriving the dopant profile: a direct method which inverts the measured SR profile directly to yield the dopant profile, and an indirect method, which derives the dopant profile from the "on-bevel" carrier profile. It is shown that while the two methods give similar results for the thick structures, the direct method is more accurate for the thin structures, particularly in determining the location of the metallurgical junction. The computation times required by both methods of a 486DX-33 computer are of the order of an hour. Sufficient details of the methods are provided for them to be implementable by users of the spreading resistance technique.