Gate shadowing effect on Ni(Pt)Si abnormal diffusion for sub-45 nm technologies

In the frame of the 40 nm technology node development, Ni(Pt)Si abnormal diffusion, usually called NiSi encroachment is studied through voltage contrast electron beam inspection. A typical mapping is found for 300 mm-Si(1 0 0) wafers which is related to NiPt deposition asymmetry, in active zones, between two transistor gates. This observation is related to “gate shadowing effect”, which induces thinner NiPt thickness and then lower Pt amount at the edge of active zones. TEM analyses of the local NiPt thickness and electrical characterizations as junction leakage permit to determine the minimum of NiPt thickness and/or Pt amount needed to guaranty an adequate NiSi stability.