| Summary: | 碩士 === 國立清華大學 === 材料科學工程學系 === 90 === Silicon nitride films, can be used as diffusion barrier layers, passivation layers, buffer layers, gate dielectrics, and tunneling dielectrics in microelectronic industry. Furthermore, in optoelectronics area, high quality GaN has been successfully grown on Si(111) using Si3N4 as a buffer layer. It is possible to fabricate new optoelectronic devices by combining GaN growth techniques with already well-established silicon device technology. The interfacial properties of Si3N4 on silicon as well as the characteristics of the film itself are two vital issues for those applications.
In the first part of this thesis, physical characteristics of the nitride film by using HRTEM, AES, XPS and STM will be discussed. In our studies, thermally grown nitride in ammonia (NH3) ambient was the best quality nitride film compared with either LPCVD grown one or N2O grown one. HRTEM observation indicated that the higher nitridized temperature get the better interfacial properties of the films. Kinetics studies shown that reaction controlled mechanism in the early stage of the nitride film growth, lead to the Si-rich nitride/Si interface. On the other head, in the latter growth stage, diffusion controlled mechanism, kept the stoichiometry condition preferable in the interface region. HRTEM also provided a cross-sectional view of the basal plane nitride grown on Si(111) substrate, and verified that the c-axis has been elongated from 2.9Å to 3.3Å.
In the second part of the thesis, electrical characteristics of the nitride films were carried out by using I-V and C-V techniques. A simple MIS structure with extra 130 Å thick LPCVD grown nitride was a standard sample. The data indicated that thermal ammonia pretreated process would help to reduce the leakage current of the sample. The reliability tests such as Qbd & tbd were also improved by the process. Higher processing temperature or longer processing time got the better electrical results. Using N2O as a pretreated gas, the electrical properties of the samples were improved more prominent, than the NH3 pretreated one. AES data suggested that the interface between nitride and Si has been converted to Si(ON)x.
|
|---|
