Larger nickel silicide particles with high resistance are observed at junction leakage. For instance, Figure 1288 shows the larger nickel silicide particle marked by the red circle encroached on the n-LDD (Lightly Doped Drain) region of NMOS transistor, while the smaller nickel silicide particle marked by the grey circle did not cause junction leakage. Note that a larger nickel silicide area represents more consumption of silicon substrate. Therefore, it was proposed that such large nickel silicide particles had phase transformation from NiSi to NiSi₂. (NiSi₂ has higher resistivity and more consumption, see page2446)

[1] ISTFA 2010: Proceedings of the 36th International Symposium for Testing and Failure Analysis.