Papers by Author: J.W. Lee

Abstract: Interfacial reaction between electroless plated Ni-P/Au UBM(Under Bump Metallization and eutectic Sn-58mass%Bi solder was studied by using AEM(Analytical Electron Microscopy). UBM is prepared by the electroless plating of Au (0.15μm ) / Ni-15at%P (7 μm ) on bare Cu substrate, and then it is reacted with Sn-58Bi solder at 220°C for 1 min. The chemical analysis using AEM provided us very consequential information about microstructure of the interface and phases formed. CBED(Convergent Beam Electron Diffraction) technique is used for phase identification of intermetallic compounds. In this study, the AEM results indicate that Ni₃Sn is formed at the P-rich Ni layer/Ni₃Sn₄ interface by crystallographic analysis. The measured primitive cell volume(104.10 Å3)of this phase is close to the N_i3Sn(103.19 ų) rather than Ni₂SnP(235.24 ų).

Abstract: We have investigated the oxidation behavior of epi-Si_0.7Ge_0.3 films in dry oxygen ambient. Epi- Si_0.7Ge_0.3 films about 500Å in thickness were deposited on (100) Si wafers by UHV-CVD system. Oxidation was carried out in a conventional tube furnace at 800 °C . In this study, it was found that Ge piles up at the oxide/substrate interface, forming a Ge-rich layer. Because of the large difference in the heat of formation between SiO₂(-730.4KJ/mol at 1000K) and GeO₂(-387.07 at 1000K) [1], the Si is to be more reactive than Ge to oxygen. The oxidation rate of SiGe in a dry oxygen environment is found to be essentially the same as that of pure Si.