High resolution medium energy ion scattering analysis for the quantitative depth profiling of ultrathin high- k layers

Ultrathin high- k layers such as hafnium oxide (Hf O2) in combination with a subnanometer Si O2or Hf silicate have emerged as Si compatible gate dielectric materials. Medium energy ion scattering (MEIS) analysis has been carried out on a range of such metal oxide chemical vapor deposition grown Hf O2/Si O2and HfSi Ox(60%Hf) /Si O2gate oxide films of thickness between 1 and 2 nm on Si(100), before and after decoupled plasma nitridation (DPN). The ability of MEIS in combination with energy spectrum simulation to provide quantitative layer information with subnanometer resolution is illustrated and the effect of the DPN process is shown. Excellent agreement on the deduced layer structures and atomic composition with the as grown layer parameters, as well as with those obtained from cross section electron microscopy and other studies, is demonstrated. MEIS analysis of a high- k, metal gate TiN/ Al2O3/Hf O2/Si O2/Si stack shows the interdiffusion, after thermal treatment, of Hf and Al from the caplayer, inserted to modify the metal gate workfunction.