Study of formation and characteristic features of silicon nitride films at RT

摘要

We have investigated various physical properties of silicon nitride films fabricated at room temperature using a non-thermal method. The nitrogen contents in the nitrides and Si-N bond nature were studied by utilizing x-ray photoemission spectroscopy. High-resolution low-energy- electron diffraction and electron-energy-loss spectroscopy have been used to explore long-range order and local Si-N vibrational characteristics in the films. The data interpreted in terms of continuous random network model Si3N tetrahedra reveal that the slow-ion deposited nitride films produced in this study resemble typical thermal silicon nitride films at high dose of N. We find that the chemical shift per Si-N bond to be 0.62 eV, and a shift of Fermi level due to nitridation less than 0.1 eV. The thermal activation energy of the film of E=400 eV with nitrogen contents, x=1.33 is found to be about 0.21 eV, in agreement with theoretical estimation. We also estimate force constants of the restoring forces, which turned out to be proportionally increasing with x. In particular, the central force constant for the in-plane stretching mode of silicon atoms varies with x in the range 297