Nano-scale characterization of poly-Si gate on high-k gate stack structures by scanning photoemission microscopy*

We have investigated poly-Si gate pattern on HfO₂/SiO ₂/Si stack structures by scanning photoemission microscopy using synchrotron radiation. Gate-pattern images have been successfully obtained by scanning the sample position during acquisitions of core-level photoemission spectra. Si 2p, Hf 4f, and O 1s core-level spectra systematically change for different sample positions, which suggests that light source focused by the zone plate is effectively utilized for nano-scale characterization of chemical states in device-pattern structures. We have also demonstrated that etching velocities of HfO₂ films on a Si substrate and shallow trench isolation vary when exposing the poly-Si gate pattern to dry etching processes.