Czochralski pulling crystal growth technique

Overview of Unit Operations. To maximize the electron or hole (carrier) mobility and thus device speed, ICs are built in single-crystal substrates. Methods of bulk crystal growth are therefore needed. The most common of these methods are the Czochralski and float-zone techniques. The Czochralski technique is a crystal-pulling or melt-growth method, whereas the float-zone technique involves localized melting of a sintered bar of the material, followed by cooling and, thus, crystallization. 

Process Stability and Control. Operationally, automatic control of the crystal radius by varying either the input power to the heater or the crystal pull rate has been necessary for the reproducible growth of crystals with constant radius. Techniques for automatic diameter control have been used since the establishment of Czochralski growth. Optical imaging of the crystal or direct measurement of the crystal weight has been used to determine the instantaneous radius. Hurle (156) reviewed the techniques currently used for sensing the radius. Bardsley et al. (157,158) described control based on the measurement of the crystal weight. 

Edge-defined film growth. A modification of the czochralski TECHNIQUE (q.v.) for growing single crystals. In the EFG technique a new die with a capillary hole is immersed in the melt, which is wicked to the top of the die by surface tension. A seed crystal is touched to its surface there, and slowly pulled away. A film of the melt spreads over the top of the die, and the growing crystal assumes the cross-sectional shape defined by the sharp edges of the die. Shapes similar to extruded cross-sections can be produced. 

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