High Depth Resolution Depth Profile Analysis of Ultra Thin High-κ Hf Based Films using MEIS Compared with XTEM, XRF, SE and XPS

Abstract

Nanometre thin high-k hafnium oxide (HfO2) layers combined with a sub-nm SiO2 layers or Hf silicate have become Si compatible gate dielectrics. Medium energy ion scattering (MEIS) analysis has been applied to a range of such MOCVD grown HfO2/SiO2 and HfSiOx(60%Hf)/SiO2 gate oxide films of thickness between 1 and 2 nm on top of Si(100), before and after decoupled plasma nitridation (DPN). MEIS in combination with energy spectrum simulation provides quantitative layer information with sub-nm resolution on these layer structures and their atomic composition that is in excellent agreement with a) the as grown layer parameters and b) results obtained from techniques, such as SE, XPS, XRF and XTEM. MEIS analysis of a metal gate, high-k TiN/Al2O3/HfO2/SiO2/Si stack shows the interdiffusion, after thermal treatment, of Hf and Al from the caplayer, which was inserted to modify the metal gate work function.