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Control of Oxygen Segregation in Czochralski Silicon Crystals Through Combining Magnetic Field and Crystal Rotation

IP.com Disclosure Number: IPCOM000042171D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kim, KM: AUTHOR [+2]

Abstract

In large-diameter Czochralski (CZ) silicon crystal growth, the oxygen level is usually high (> 30 ppma), and radial and axial uniformity does not exist. According to the teachings of the present disclosure, thermal convection is suppressed by an axial magnetic field, and by varying the crystal rotation rate, oxygen concentration is controlled to a low to medium level by virtue of the forced convection due to the crystal rotations. In the CZ silicon crystal growth, a fused silica crucible is used to contain the silicon melt. As a result of the reaction and dissolution of the fused silica, the silicon melt is contaminated with silicon-oxygen species.

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Control of Oxygen Segregation in Czochralski Silicon Crystals Through Combining Magnetic Field and Crystal Rotation

In large-diameter Czochralski (CZ) silicon crystal growth, the oxygen level is usually high (> 30 ppma), and radial and axial uniformity does not exist. According to the teachings of the present disclosure, thermal convection is suppressed by an axial magnetic field, and by varying the crystal rotation rate, oxygen concentration is controlled to a low to medium level by virtue of the forced convection due to the crystal rotations. In the CZ silicon crystal growth, a fused silica crucible is used to contain the silicon melt. As a result of the reaction and dissolution of the fused silica, the silicon melt is contaminated with silicon- oxygen species. Incorporation of the oxygen into the silicon crystal in terms of the concentration and the uniformity of the radial and axial distribution are then controlled by the rate of dissolution and fluid flow conditions in the melt. In large- diameter CZ silicon crystal growth, control of the oxygen below about the 30 ppma level and also control of the radial and axial uniformity are difficult to be implemented. The figure illustrates schematically the present CZ silicon crystal growth arrangement with an axial magnet. The application of a magnetic field in the crystal growth has been known to dampen or suppress thermal convections in the melt [*]. In our invention, a relatively low magnetic field of about 1 kg...