Improved formation of silicon dioxide films in liquid phase deposition

Abstract

This work is to reveal the novel technique of liquid phase deposition silicon dioxide (SiO2) films which will increase the deposition rate and also improve the film quality. It is well known that deposition at a lower temperature without residual OH− on the substrate is difficult to achieve. Therefore, it is important to treat the substrate wafer before deposition. The substrate surface dipped into hydrofluoric acid (HF) is usually terminated with hydrogen (H) and has hydrides (Si–H) which react with water so that hydroxyls (Si–OH) can be obtained. No silicon dioxide can be grown on a clean Si substrate without native oxide. Therefore, a model is proposed to show that native oxide growth with chemical pretreatment of HF and ultrapure deionized water has rich hydroxyl (OH) molecules on surface in order to grow silicon dioxide. Another constant parameter, the growth rate of SiO2 is found to increase linearly with the time of reaction with ultrapure deionized water. At the same concentration of boric acid and hydrofluosilicic acid, the corresponding deposition rate of SiO2 is found to be about 70 Å/h larger than the films which are grown without reacting with chemical pretreatment of HF and ultrapure deionized water. In this study, the refractive index and deposition rate are found to be as high as 1.47 and 1400 Å/h, respectively. Good and reliable quality SiO2 film grown in this work was supported by various analytical techniques, such as Fourier transform infrared, Auger electron spectroscopy, refractive index measurement, etching rate measurement, and leakage current measurement.