Some gettering processes like internal gettering or backside damage gettering base on heterogeneous precipitation of metal impurities at defects in pre-de ter mined parts of silicon wafers during cooling from high temperatures. We consider microscopic properties of effective heterogeneous nucleation sites for cobalt, nickel and copper impurities from the fundamental point of view of suicide precipitate formation. We follow the basic concept that such gettering sites are defects which allow fast precipitation, i.e. which remove kinetic limitations known from homogeneous precipitation of these impurities at small supersaturation. For Co and Ni it follows that distorted lattice sites in the core of dislocations may establish high incorporation rates of interstitial atoms into suicide particles, whereas for Cu sinks for silicon self-interstitials are suitable gettering sites.