In situ spectroscopic ellipsometry was utilized in an atomic-layer-deposition (ALD) reactor for rapid and rational gate stack process optimization of the trilayer dielectric HfO2/Al2O3/GeOx on Ge. The benefit of this approach was demonstrated by developing an entire process in situ: 1) native oxide removal by hydrogen plasma; 2) controlled reoxidation for Ge surface passivation; and 3) deposition of Al2O3 and HfO2 using thermal ALD. The low-k layer thicknesses were scaled down without losing their respective functions, i.e., GeOx to form an electrically well behaved interface with Ge and Al2O3 to thermodynamically stabilize the GeOx /Ge interface. Aggressive equivalent-oxide-thickness scaling of the trilayer stack down to 0.85 nm with a low gate leakage of 0.15 mA/cm2 at VFB-1 V was achieved, while preserving a high-quality dielectric-semiconductor interface.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering