Research was carried out on the low-temperature, large-area surface nitridation and oxidation of monocrystalline silicon by plasmas generated by Electron Cyclotron Resonance (ECR) microwave discharges. At temperatures below 80°C, the uniform silicon nitride and silicon dioxide layers were obtained. By combining the optical diagnostics and composition detection of the plasmas, the mechanism of the ECR plasma treatment was discussed. The results show that this method can efficiently treat silicon surfaces at low temperatures, with large-area uniform silicon nitride and silicon dioxide layers obtained.