Morphological and structural studies of silicon oxynitride films (SiOxNy) obtained by PECVD technique.

Author(s)

Denise Criado Pereira de Souza

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola Politécnica (EP/BC)
• Defense date: 2007-07-31

Examining board members

Inés Pereyra; José Alexandre Diniz; Ely Antonio Tadeu Dirani; Ronaldo Domingues Mansano; Rogério Junqueira Prado

• Advisor: Inés Pereyra

Abstract

In this work results on the morphological and structural characterization of silicon oxynitride (SiOxNy) films deposited by plasma enhanced chemical vapor deposition technique (PECVD) at low temperature (320°C) are presented. The main goal is to correlate the chemical composition of amorphous SiOxNy alloys to their optical, structural, morphological and mechanical properties intending applications on electrical, optoelectronic and micromechanical devices. The proposal is to continue previous research developed in this group, which demonstrated the possibility of tuning the chemical composition and, consequently, the SiOxNy films properties such as refractive index, dielectric constant and photoluminescence by the precise control of the deposition parameters. The deposition conditions were adjusted in order to obtain to material types, SiOxNy films with tunable chemical composition between SiO2 and Si3N4 and silicon-rich SiOxNy. The characterization was performed by elipsometry, refractive index by coupled prism, RBS (Rutherford Backscattering Spectroscopy), FTIR (Fourier Transform Infrared Spectroscopy), XANES (X-Ray Absorption Near Edge Spectroscopy) on K edge of Si, O and N, residual stress measurement and Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The films with chemical composition between SiO2 and Si3N4 presented stable structural arrangement with temperature, maintaining the chemical bonds and the amorphous structure after high temperature annealing. Also the results demonstrated the possibility of producing a low residual stress material and an adjustable refractive index since in the 1.46 to 2 range, excellent result for MOEMS devices (micro-opto-electro- mechanical systems applications. For silicon rich-samples the formation of different phases was observed, one formed by Si clusters and other one by a mixture of Si-O and Si-N bonds. Depending on the Si content and on the annealing conditions this material can present nanocristals, results which allowed us to understand and to optimize this material for light emitting devices applications. (AU)