Interfacial solid-phase reactions, crystallographic structures, and electrical characteristics of Hf/(001)Si systems

Interfacial solid-phase reactions, crystallographic structures, and electrical properties of Hf/(001)Si systems have been investigated as a function of annealing temperature. For Hf/n+-Si systems, extremely low contact resistivities of 7.3×10−8 and 5.8×10−8 Ω cm2 have been achieved at annealing temperatures of 460 and 580 °C, respectively. A bilayer structure of an epitaxial Hf3Si2 and an amorphous layer is formed at the interface by annealing at 460 °C, and an epitaxially-grown Hf3Si2 layer covers the interfacial layer at 580 °C. The current flowing through the interface of Hf/n-Si is dominated by the thermionic emission for these annealing conditions. The Schottky barrier heights, whose values are 0.50 and 0.46 eV at 460 and 580 °C, respectively, are lower than those of HfSi and HfSi2. It has been found that the decrease in contact resistivity of the Hf/Si systems is mainly caused by the lowering of the Schottky barrier height and an improvement of interfacial defects by annealing.