Scanning Electron Microscopy


Capacitive coupling voltage contrast (CCVC) allows electron-beam testing of passivated integrated circuits (IC) without radiation damage or prior, time-consuming specimen preparation. This effect occurs when low primary electron energies are used and the electron yield of the passivation layer is greater than 1. Signal changes in the relevant interconnections are transferred to the passivation surface via capacitive coupling, but they vanish there within the storage time due to electron irradiation. A physical model explains the dependence of CCVC on three parameters: electron irradiation, the passivation material and the signals within the IC. Computer simulations based on this model describe the experimentally-obtained dependencies of the storage time with precision and al low predictions to be made for using CCVC in electron beam testing. The requisite modifications to the electron beam testing system are described and the possible uses of CCVC for testing passivated devices within IC are demonstrated on the basis of examples.

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