Room temperature transformations induced in SiO2 layers by chemical compounds: I

Transformations in the structure and the composition of SiO₂ films as a result of the action of some organic compounds at room temperature were studied by various methods. Secondary ion mass spectrometry (SIMS) showed that hydrogen-containing species were removed from the SiO₂ layers (which were prepared by the thermal oxidation of silicon wafers) after a prolonged exposure to diethyl ether vapour. Electron microscopy and electron diffraction studies showed that the exposure led to the development of a crystalline phase in the SiO₂ layer. SIMS and transmission electron microscopy measurements both supported the view that the transformation from an amorphous structure to a denser more crystalline phase took place as a result of an interaction between molecules of diethyl ether and the SiO₂ surface. The removal of hydrogen-containing species seems to be a condition for this kind of transformation.In a recent short note¹ we have presented some preliminary results concerning amorphous-to-crystalline phase transformations in SiO₂ films which were prepared by the thermal oxidation of silicon wafers and which were treated at room temperature with various (mainly organic) compounds.Electron microscopy and electron diffraction studies clearly revealed the presence of a crystalline phase. Of the compounds investigated diethyl ether seemed to be the most active in inducing this type of transformation.In the following, more results will be given of investigations performed with the aim of understanding the phenomena and an explanation of the transformation mechanism will be offered.