Chemical contamination of thin oxides and native silicon for use in modern device processing

The characterization of native oxide residuals and contaminants during the clean-up of silicon substrates prior to oxide growth is crucial for the development of accurate growth algorithms. Studies of contaminant concentrations based on Auger analysis are reported, showing carbon to be the critical contaminant. A critical etching time is established, for which carbon content and residual native oxide thickness are minimal. Variations in refractive index with etching period and native oxide thickness are also reported, showing an increase in refractive index with increase in native oxide thickness. These results should prove useful in improving the accuracy of ellipsometric techniques, and will aid in growth algorithm development.