Resistive radiant heating elements are currently used for many processes in silicon production and limit the heating/melting rate of silicon. Induction furnaces, however, with their ability to deliver heat directly or indirectly into a mass of silicon, make them the preferred choice for the next generation of thermal equipment for solar-grade silicon production.
Coreless Induction Furnaces
Inductotherm’s coreless induction furnaces offer superior performance and outstanding durability, and are more efficient, more productive, quieter and easier to maintain than competitive furnaces. They are ideal for melting all metals, including silicon.
- Heavy steel shell provides maximum furnace rigidity and strength for long lining life, low furnace noise and minimum EMF emissions.
- Induction coil is split into two or three sections to create a “running” electromagnetic wave that causes vigorous stirring of the molten bath.
- Electromagnetic shunts cover more that 50% of the coil’s circumference, redirecting the electromagnetic field into the melt.
- Graphite susceptor lining carries the current and heats the metal before the molten silicon becomes conductive.
- Optional vacuum cap creates controlled environment for gas purging to remove boron and phosphorous from molten silicon.
- Casting spout pours silicon into molds or kettles to harden before further refining.
Ingot producers depend on Inductotherm’s systems for melt flexibility and product uniformity. For ingot makers, the correct amount of induction stirring is a key factor in producing ingots that are metallurgically homogeneous from the start to the finish of each batch. Our induction melting systems are designed to produce the best level of stirring for each customer’s application.
Vacuum and Controlled Atmosphere Systems
Some processes require that silicon be refined to a high level of purity. This can be achieved in large quantities using Inductotherm’s vacuum and controlled atmosphere systems, custom designed to meet the requirements of each of our customer’s process needs.
Power Supplies and System Components
The use of our induction technology in applications such as the Fluidized Bed Reactor and Crystal Pulling has revolutionized the Photovoltaic Industry, allowing for energy efficient and controllable power to create high quality multicrystal and monocrystal silicon ingots.
Multi-SwitchTM Power Systems for Fluidized Bed Reactors
In the fluidized bed process, pure silicon pellets are grown from tiny pure silicon seeds into polysilicon granules in a high-temperature reaction vessel.
To dramatically increase the yield of these high-temperature reaction vessels, also called fluidized bed reactors, Inductotherm developed a special multi-zone coil and patented Multi-SwitchTM power supply. This system allows time-sharing of the power from a single inverter and applies it to different coil zones, thereby supplying variable and adjustable energy flow to various sections of the susceptor.
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