Gettering of carbon and oxygen in silicon processing

The control of carbon and oxygen is of great importance in today's silicon materials and device processing, and it will become a critical parameter in the immediate future for VLSI device processing. Although considerable technology and some understanding are available today in the control of oxygen in silicon materials through processing, there is little technology and even less understanding of carbon control in silicon wafer processing. We have determined, for high carbon content silicon, that carbon can be gettered to damage sites such as dislocations, stacking faults, and/or wafer surfaces, thus creating a carbon-denuded zone in epitaxial silicon, as will as in bulk Czochralski silicon substrates. The gettering effects of carbon have been investigated using controlled time, temperature, and ambient gas thermal anneals. The characterization of these materials was carried out using chemical etches, Fourier transform infrared spectroscopy, and scanning Auger microprobe analysis.