MORPHOLOGICAL EVOLUTION OF THE LOW-TEMPERATURE OXIDATION OF SILICON WITH A GOLD OVERLAYER

Low-temperature oxidation of silicon with a gold overlayer has been studied by in situ reflected high-energy electron diffraction, Auger electron spectroscopy, and transmission electron microscopy. In nonultrahigh vacuum (non-UHV) deposited (001) samples, wet oxidation was found to proceed more rapidly than that of UHV deposited (001) samples. In samples annealed at 220°C, an oxide layer was found to rapidly develop between a two-layer structure of Au films. Au globules were observed to disperse in the oxide layer after an extended period of oxidation. The difference in the oxidation behavior between UHV and non-UHV samples is attributed to the absence and presence of empty channels between the Au grains. In UHV deposited (111) samples wet oxidized at 220-250°C for various periods of time, the oxide was found to grow initially on top of the Au layer. Both the thickness of the oxide layer and the unevenness of the Au layer were found to increase with annealing time. The presence of highly textured Au/Si interface in (111) samples led to the retardation of oxidation process. The morphological evolution observed in the present study is used to explain the dependence of maximum oxide thickness on starting Au layer as well as the termination of oxide growth. © 1995 American Institute of Physics.