Microstructural information from optical properties of LPCVD silicon films annealed at low temperature

The structural and morphological properties of low temperature annealed (600 °C, for 26 h) LPCVD silicon layers prepared from pure silane in a large range of deposition temperatures (500–615 °C) and pressures (20–100 Pa) have been investigated in order to see the changes appearing in the LPCVD Si film with respect to the as-deposited films. The physical characterization of as-deposited and annealed films has been performed by X-ray diffraction (XRD), spectroellipsometry (SE) and atomic force microscopy (AFM) techniques. Surface roughness information extracted from AFM and SE showed good agreement and revealed the annealing effect on LPCVD Si films as a function of CVD condition. The crystalline phase evolution in LPCVD Si films at different annealing temperatures was studied by XRD and SE techniques. A high degree of crystallization was obtained in all silicon films. Two models, Tauc and Cody (applied to the ellipsometric spectra), were used to estimate the evolution of the optical band gap with the annealing. The results show a strong link between annealing and deposition temperatures on the one hand and the physical and optical properties of polysilicon films on the other hand. [Copyright &y& Elsevier]