Hf-related Gate Oxide Thickness Mapping Using XRR/XRF

Abstract

For over 10 years the semiconductor industry has ardently pursued the research and development for a gate oxide that would replace silicon oxide nitride with a higher dielectric constant material in order to reduce gate leakage and continue Moore's Law scaling. The industry consensus has been Hf-related oxides such as hafnium oxide (HfO2), hafnium silicate (HfSiO), and nitrogen-doped hafnium silicate (HfSiON). One of the process goals for the thickness uniformity of these Hf-related gate oxides is +4% (3 sigma) of the Equivalent Oxide Thickness (EOT) which is the physical thickness divided by the dielectric constant of the new gate oxide scaled to the SiO2 dielectric constant. The work presented here is to show the capability of XRR/XRF for mapping the uniformity of the physical thickness of Hf-related gate oxides using the Technos S-MAT 2300.