Infrared absorption study of HfO₂ and HfO₂/Si interface ranging from 200cm^-1 to 2000cm^-1

In this paper, we report infrared absorption studies of HfO₂, HfO₂/Si interface and Hf_(1-x)Si_xO_y. Both HfO₂ crystallization and SiO₂ formation at the interface can be clearly detected in the absorption spectra in the far and middle infrared regions, respectively. By measuring the intensity change and the peak shift of infrared absorption spectra as functions of annealing temperature and time together with XRD patterns, we discuss a difference of the amorphous structure between HfO₂ and SiO₂, and also show an evolution of HfO₂ crystallization in the monoclinic phase up to 1000°C. On the other hand, it is shown that the interfacial SiO₂ layer is qualitatively similar to the thermally grown SiO₂. Furthermore, it is demonstrated that a Si incorporation into HfO₂ film significantly changes the IR absorption spectra, and that the Hf _(1-x)Si_xO_y film is phase-separated with an appearance of modified monoclinic phase by higher temperature annealing.