Three-Dimensional Structure Analysis of Metal--Oxide--Insulator Field Effect Transistors with Different Electrical Properties by Scanning Transmission Electron Microscopy

To clarify the origin of on-state drain current ($I_{\text{ON}}$) variability in metal--oxide--semiconductor field-effect transistors (MOSFETs), we applied three-dimensional scanning transmission electron microscopy (3D STEM) observation to two transistors that had different $I_{\text{ON}}$ values but the same threshold voltage ($V_{\text{T}}$). The results clearly showed a difference in the distance between the gate and source/drain silicide, suggesting that the $I_{\text{ON}}$ difference between two transistors can be explained by the difference in the source/drain extension resistance. We showed that it is possible to discuss the 3D device structures in relation to their electrical characteristics.