Electrial Actvity of Silicide Precipitates

It is well known that metal-silicide precipitates give rise to strong excess carrier recom­bination and at high density may dominate the electrical behavior of other extended defects such as dislocations [134] and grain boundaries [135]. Kittler et al. [60] pro­vided a phenomenological relation between the minority carrier diffusion length LD and the density Np of NiSi2 precipitates as LD « 0.7 x Np1/3 and reported EBIC contrasts of several tens of per cent also for Cu-rich precipitates [61]. Similar values have recently been observed by Saring et al. [136] for defects formed during coprecipitation of Cu and Ni in Si. The recombination properties have been described in terms of a Schottky-effect model based on thermionic electron emission [137] similar to the treatment of copper silicide precipitates at grain boundaries in silicon [135]. For a more detailed description and discussion of DLTS data please refer to [37].