Nitrogen doping grown-in defects engineering in silicon crystals and argon-annealed wafer

Over the last 30-years in the history of increasing shrinkage of the design rule and the high integration of integrated circuits, what was essential in the development and production of silicon crystals was the technology to control the characteristics of grown-in defects of Czochralski silicon crystals, especially octahedral voids and oxygen precipitates. This paper describes a defect engineering technology employing nitrogen doping capable of controlling both the voids and the oxygen precipitates. Nitrogen doping renders the voids to assume a tabular triclinic shape and to shrink in size and, at the same time, makes minute oxygen precipitates form in the crystals in high concentration. When heat-treated in an argon atmosphere, the crystals thus obtained will make ideal wafers having a defect-free surface layer showing excellent electric properties and a bulk with highly concentrated defects showing a high gettering capacity of impurities. This method produces excellent wafers at a cost lower than epitaxial wafers having equally good defect-free surfaces. Therefore, it is expected to offer wide applicability to the fabrication of a variety of devices for which low cost is needed.