IMPURITY DECORATION OF DEFECTS IN FLOAT ZONE AND POLYCRYSTALLINE SILICON VIA CHEMOMECHANICAL POLISHING

The behavior of impurities introduced in single and polycrystalline silicon via chemomechanical polishing was studied extensively. Using the electron beam induced current mode of a scanning electron microscope, chemomechanical polishing of boron-doped FZ silicon is shown to introduce impurities which decorate and electrically activate swirl defects. Undecorated swirl defects do not behave as carrier recombination sites. Chemomechanical polishing and preferential etching of boron-doped polycrystalline silicon produced etch pits which increased in concentration with decreasing resistivity, indicating an interaction between the polishing impurity and boron. The impurity is shown to form discrete points of electrical activity homogeneously in a thin surface region of the material as well as increase the electron beam induced current contrast of dislocations and grain boundaries.