In-line inspection on thickness of sputtered HfO2 and Hf metal ultra-thin films by spectroscopic ellipsometry

HfO2-based dielectrics are most promising high k materials to substitute SiO2 for the MOS gate dielectric. To guarantee the deposition process under well control, an inline inspection to characterize the thickness and uniformity of both HfO2 and Hf metal ultra-thin films must be established. In this work, we proposed an in-line, non-destructive optical method to measure thickness of both films, and this method has potential to be inducted into production control. Upon Spectroscopic Ellipsometry (SE), reactive DC sputtered HfO2 and Hf metal ultra-thin films with featured-thickness of 40 Angstrom or larger were well analyzed, and accuracy of wafer mapping measurement fell in 3 Angstrom.