Dopant delineation: novel technique for silicon dopant implantation defects identification

Electrical properties of semiconductor devices change drastically with doping. Doping alone has no distinguishable topographical contrast or carrier concentration levels when compared to a non-doped area of an active region. As a result of that, dopant profiling and p-n junction delineation has become one very critical step in failure analysis to identify and confirm dopant abnormalities. One of the most promising techniques for two-dimensional delineation of dopants in silicon is based on chemical etching of doped regions and subsequent observation using the scanning electron microscope (SEM) or transmission electron microscope (TEM). This paper presents the use of focus ion beam (FIB) cross sectioning and selective chemical etching to perform p-n junction delineation for identifying dopant implantation defects at silicon level.