| 摘要 |
<p>Heavy metal contamination attributed to ion injection or high-temperature heat treatment can be efficiently trapped within a bulk layer. There is provided a process comprising the step of injecting oxide ions in the internal part of wafer (11) and the step of subjecting the wafer to the first heat treatment in a given gas atmosphere at 1300 to 1390°C to thereby form not only embedded oxide layer (12) but also SOI layer (13), characterized in that the wafer before the oxide ion injection has an oxygen concentration of 9x10<17> to 1.8x10<18> atoms/cm<3> (old ASTM), and the embedded oxide layer is formed over the entire surface of the wafer or part thereof, and that before the oxide ion injection step or between the oxide ion injection step and the first heat treatment step, there are conducted the second heat treatment step of forming oxygen precipitate nuclei (14b) in the internal part of the wafer and the third heat treatment step of growing the oxygen precipitate nuclei (14b) formed in the internal part of the wafer to oxygen precipitates (14c).</p> |
