Interfacial Diffusion Studies of Hf and Zr into Si from Thermally Annealed Hf and Zr Silicates

Abstract

AbstractHf and Zr incorporation from thermally annealed high-κ gate dielectric thin films (4-5 nm) candidates HfSixOy and ZrSixOy into Si are presented. The dielectric films were subjected either to rapid thermal annealing (RTA) or standard furnace annealing in an N2 atmosphere. After annealing, the films were removed by chemical etching prior to depth profiling using both time of flight secondary ion mass spectroscopy (ToF-SIMS), and Heavy Ion Rutherford Backscattering Spectrometry (HI-RBS) combined with UV-ozone oxidation/etching cycles. As-deposited and annealed films were studied using monochromatic X-ray Photoelectron Spectroscopy (XPS), and high resolution TEM. A Zr incorporation depth after annealing of up to 20 nm into the Si substrate was observed. Depth profiling shows that, although most of the remnant Zr after annealing/etching is located at or near the surface of the Si substrate, incorporation into the substrate is also present. No significant Hf diffusion into Si was observed for either RTP or furnace-annealed films