Factors affecting two-dimensional dopant profiles obtained by transmission electron microscopy of etched p-n junctions in Si

Abstract

Transmission electron microscopy (TEM) was used to characterize image contrast obtained from doping-dependent etching of p-n junctions in silicon. The local variations in crystal thickness give rise to the appearance of thickness fringes which may be interpreted as two-dimensional iso-concentration contours that map the dopant distribution. The samples used for the study consisted of solid source diffusions of boron into substrates of varying resistivities of both n- and p-type. The factors which affect the interpretation of dopant profiles obtained from selective chemical etching of cross section TEM samples is addressed. One-dimensional chemical dopant concentration data were derived from secondary ion mass spectroscopy and one-dimensional carrier concentration data were derived from spreading resistance profiling.