Measurement of shallow dopant profile using scanning capacitance microscopy

The shallow dopant profile of a 100-nm-deep n(+) layer separated by a 300-nm-wide shallow trench isolation (STI) region has been measured using scanning capacitance microscope (SCM). The conduction type of the sample can be obtained by analyzing the dC/dV phase and amplitude profiles obtained by SCM mesurement, where C and V are capacitance and applied voltage, respectively. The structure and size of STI obtained by SCM measurement were compared with those by scanning electron microscope observation. A two-dimensional (2D) simulation of the sample structure was used to extract the carrier density profile from the dC/dV versus the depth data profile obtained by SCM measurement. The ID carrier distribution was compared with the carrier simulation profile for reference. From the sample surface down to a depth of 100 nm, the electron density profile was in good agreement with the simulated one. In addition, the depletion layer at and near 100 nm was observed consistently with the simulation profile.