Wide Spectrum Monitoring Technology And Its Application Of Thin Film Growth

The manufacturing of the optical thin film devices with high performance depends on the development of the advanced film deposition, monitoring and measurement techniques. As one type of the important monitoring techniques for film deposition, optical monitoring methods have always attracted much attention. In place of conventional single wavelength monitoring, multi-wavelength monitoring and broadband optical monitoring have been developed. With the purpose of improving the effect of the monitoring methods for film deposition and the quality of the deposition technique, the work focused on developing a broadband optical monitoring system and studying the effect of the deposition rate,film thickness,temperature etc. on the optical constants of the deposited films. The main work is shown as follows:1. A broadband monitoring system was set up with solving encountered software and hardware problem and applied to an electron beam evaporation system for film deposition. The conventional data processing was improved and the computational amount was obviously reduced. Both hardware-based and software-based methods were proposed to filter the interferential effect caused by the substrate. The noise-filtering methods were applied to the real deposition of narrow band filters using both K9 glass and silicon as substrates, and with in-situ error compensation process based on BOM technique, several narrow band filters with good performance, which is in accordance with the theoretical design, were finally obtained. The results demonstrated the validity of this broad band monitoring method on film deposition.2. The thickness dependence of the optical constants of SiO2 films at different deposition rates was studied. All samples of SiO2 films with thickness ranging from～1 nm to 600 nm were deposited on Si substrates by EBE method, and then measured with variable-angle spectroscopic ellipsometry(VASE). More than 200 sets of ellipsometric parameters were obtained for each sample. The optical constants and thicknesses of SiO2 films have been obtained with fitting the measured data using appropriate model. The results showed that the evolution of optical constants of SiO2 films with thickness differs for the samples deposited at higher rates and the samples at lower rates, and it is favorable to deposit films at low rate for getting denser film.3. The temperature dependence of optical constants of solid materials was analyzed using the single-oscillator-based Lorentz dispersion model. The spectroscopic ellipsometer was applied to the measurement of the samples at different temperature and a self-built sample box with temperature variable was used to keep sample at a certain temperature during measurement. The dispersion curves of samples for various temperatures were obtained. At present, the temperature dependence of optical constants for Si and Au samples were studied using the spectroscopic ellipsometry (SE) with temperature variable. The results showed that, the optical constants of materials change with temperature, and the trend of variation with temperature for the optical constants below the gap and above the gap is different, which is in accordance with the theoretical analysis using the Lorentz dispersion model with considering temperature effect. The SE with temperature variable can be applied to determination of the energy gap for some solid materials such as semiconductors.