Si rich oxide (SRO) thin films were annealed by two-step rapid thermal annealing (RTA) to form SiO2-matrix silicon-nanocrystals (Si-NCs). The effects of the amount of Si rings in SRO thin films on the phase separation and crystallization processes of annealed thin films were investigated using Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Results showed that the amount of Si rings exerted little effects on the phase separation and the crystallization of SiO0.7 thin films. Moreover, the amount of Si rings significantly influenced the crystallization of SiO1.5 thin films. The crystalline fraction of 1000 degrees C-SiO1.5 thin films firstly increased from 7% to 15% with increased of the amount of Si rings. The changes in crystallization processes were most possibly due to the different amount of Si-O-4 bond in the SRO thin films with different amount of Si rings. Our work indicated that the amount of Si rings could facilitate the crystallization of annealed thin films with higher O/Si atomic ratio. (C) 2015 Elsevier B.V. All rights reserved.