Continuous Czochralski Growth of Silicon Single Crystals

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A continuous solid-feed Czochralski (CCZ) growth process for silicon single crystals will be researched. By reducing the melt height and keeping it fixed, this process can suppress many kinds of unsteady kinetics and inhomogeneities. The impurity build-up, the oxygen incorporation and the resistivity in axial direction can be much better controlled by continuously charging the polysilicon and doping. The design of a commercially viable CCZ process which can produce crystals of much better quality and at lower costs will be developed. A three-dimensional numerical study of convective transport processes involving heat, mass and momentum transfer together with the melting of solid pellets and solidification at the melt/crystal interface will be performed to characterize the process parameters suitable for continuous growth of crystals. Innovative techniques for flow visualization and heat transfer experiments will be used to develop a basic understanding of thermohydrodynamic phenomena and pellets melting. Based on this information, suitable modifications in the present CZ crystal puller will be researched and the optimal conditions for CCZ growth will be characterized. Full-scale experiments will then be conducted at an industrial research facility. This collaborative research effort between the university and industry is expected to lead to the development of an efficient, cost-effective CCZ unit which should be of great importance to the United States semiconductor industry.