Nitrogen Doping Grown-in Defects Engineering in Silicon Crystals and Argon-annealed Wafer

摘要

Over the last 30-year in the history of increasing microscopic precision and high integration of integrated circuits, what was essential in the development and production of silicon crystals is 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. The 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 the excellent wafers at a lower cost than epitaxial wafers having equally good defect-free surfaces and, hence, is expected to offer wide applicability to fabrication of varieties of devices for which low cost is essential.