In Situ Analysis of Oxygen Vacancies and Band Alignment in HfO₂/TiN Structure for CMOS Applications

The density of oxygen vacancies characterization in high-k/metal gate is significant for semiconductor device fabrication. In this work, a new approach was demonstrated to detect the density of oxygen vacancies by in situ x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) measurement. Moreover, the band alignment of the structure with optical band gap measured by spectroscopic ellipsometry (SE) and valence band offset by UPS were reported. The specific areal density of oxygen vacancies in high-k dielectric of HfO₂/TiN was obtained by fitting the experiment data to be 8.202 × 10¹⁰cm^- 2. This study would provide an effective approach to characterize the oxygen vacancies based defects which cause threshold voltage shifts and enormous gate leakage in modern MOSFET devices.