Formation of silicon-oxide layers at the interface between tantalum oxide and silicon substrate

Silicon-oxide layers formed at the tantalum-oxide/silicon interface were investigated by using Fourier transform infrared spectroscopy (FTIR). The samples were annealed in oxygen atmosphere, in nitrogen atmosphere, and in vacuum. It has been found that the formation of the interfacial silicon-oxide layers depends neither on the tantalum-oxide thickness nor on the annealing atmosphere, but on the annealing temperature. The silicon-oxide layer is formed even by annealing in vacuum. It is concluded that the silicon-oxide layer is formed not by a diffusion of the oxygen from the annealing atmosphere, but by a reaction between the tantalum-oxide film and the Si substrate. FTIR analysis and transmission electron microscopy of the interfacial layer show that the silicon-oxide layer has a bonding configuration different from a pure silicon dioxide. (C) 1999 American Institute of Physics. [S0003-6951(99)03948-0].