Direct observation of Ni decorated dislocation loops within As+-implanted silicon and arsenic clustering in Ni silicide contact
The redistribution of arsenic and nickel during the reaction of Ni thin films with arsenic doped Si(100) substrates is studied by a combination of transmission electron microscopy (TEM), atom-probe tomography (APT) and in situ X-ray diffraction (XRD). Ni was observed at the edges of a pseudo-hexagonal dislocation loop within As+-implanted (001)Si wafers, after recrystallisation of preamorphised Si and deposition of 100nm Ni. After an additional heat treatment at 280C, the same concentration profiles were found with a maximum of ?10% Ni at the edges of the dislocation loops, suggesting Cottrell atmospheres. In situ XRD showed the formation of a transient phase forming isolated grains at the ?-Ni2Si/Si interface. Clusters containing 10% of As are present only in the transient phase. The presence of As clusters in silicide used for contact on devices might have significant influences on devices properties.
dislocation thin films preamorphisation cottrell atmospheres implantation nickel silicide diffusion segregation atom probe tomography