Ultra thin silicon nitride films have been indispensable in high density memory devices as a dielectric. We investigated the effect of the silicon surface state on initial silicon nitride growth process, we have used X-ray Photoelectron spectrometry (XPS), Secondary ion mass spectrometry(SIMS), and Capacitance-Voltage(C-V) characteristics. The results of our study show that the fluorine on silicon surface influences initial silicon nitride growth. The presence of fluorine delays low pressure chemical vapor deposition(LPCVD) silicon nitride growth as well as restraining native oxide growth at the silicon nitride/silicon substrate interface. We propose that it is a key process of thin dielectric films deposition to control fluorine on silicon surface.