Float Zone Systems

The FZ-14M(G) Float-Zone crystal-growing system is designed for preparing samples of monocrystalline Silicon crystals for material analysis in industrial Polysilicon production. Small polycrystalline samples from the production process are inductively melted in an Argon atmosphere and crystallize on a seed crystal to form a single crystal, which then undergoes a spectrometric analysis to determine and document the quality of the Polysilicon produced. The contactless melting process—the high final vacuum generated through the use of a turbomolecular pump and ultra-pure Argon as a process atmosphere—effectively prevents contamination during the process.

The FZ-14M(G) allows granulate to be placed under the coil and small single crystals for material analysis to be pulled with the help of a seed crystal at the upper feed in a process with the opposite pulling direction. In addition, the upper spindle can be moved in either the X or Y direction.

The FZ-30 and FZ-35 Float-Zone crystal-growing systems are designed for the industrial production of monocrystalline Silicon crystals with a diameter of up to 200 mm (8"). Depending on the dimensions of the source rods, crystals with a length of up to 2,000 mm can be pulled. The crystal diameter and height of the liquid zone during the process can be monitored using a camera. The contactless melting process—the high final vacuum generated through the use of a turbomolecular pump and ultra-pure Argon as a process atmosphere—effectively prevents contamination during the process.

To cultivate large crystals, an Argon atmosphere can be generated with an overpressure of up to 3 bar in the FZ-30 and up to 5 bar in the FZ-35. Both the upper spindle and the coil can be positioned automatically. In the FZ-30, the upper spindle can be moved in either the X or Y direction. Both system types also allow Nitrogen to be introduced into the process chamber in a controlled manner. We offer a range of additional options such as a gas doping system for doping the crystals, a closed DI cooling water system, a shaper for the source rods, and a system for adjusting the orientation of the seed crystal.

The SR110 slim-rod puller works like a Float-Zone system. This system uses a polycrystalline Silicon rod (source rod), with a diameter of 100 mm under the high-frequency induction coil. Depending on the length of the Silicon rod, a specific number of slim rods can be generated in a multi-pulling process; these are then used as filaments in downstream Siemens processes. An isolation valve separates the receiving chamber from the process chamber, which means that the finished slim rods can be removed and the next process started immediately. The slim rods can also be doped through the introduction of process gases that diffuse into the melt.

A modified slim-rod puller design uses two source rods with a diameter of around 50 mm, from each of which slim rods are pulled.