Effect of substrate temperature and post-deposition annealing on intrinsic a-SiO_x:H film for n-Cz-Si wafer passivation

In order to make sure the co-operation of substrate temperatures and post-deposition annealing on the structure and performance of the a-SiO_x:H for n-Cz-Si wafer passivation, three series a-SiO_x:H films bifacial-deposited on n-Cz-Si wafers were made. In which, the first series was deposited at room temperature and post-deposition annealing with different temperature; the second series was deposited with different substrate temperature and without post-annealing; and the third series was deposited with different substrate temperature and post-annealed at the optimized 275 °C. Effective lifetime of the samples was tested by QSSPC method, and the imaginary part of dielectric constant (ε ₂) and film properties of the films were analyzed by Spectroscopic Ellipsometry and Fourier Transform Infrared Spectroscopy. It is concluded that (1) the structure and passivation effect of a-SiO_x:H films on n-Cz-Si wafer are sensitive to the substrate temperature and post-deposition annealing, and the optimum scheme is depositing the film at 100 °C and post-annealing the wafer at 275 °C; (2) the microstructure parameter R ^* of the a-SiO_x:H is ~0.67 for the samples with the optimum passivation effect.