Silicon Melting

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.

Unidirectional Stirring

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.

Induction Melt Systems Designed for Controlled Atmospheres

Our vacuum cap furnaces are ideal for the removal of boron and phosphorus from bulk silicon by gas purging or vacuum evaporation.

Inductotherm Melt Benefits:

Superior Performance and Durability of Our Coreless Melting Furnaces
Smaller Chamber for Rapid Evacuation of Gasses
Designed for Vacuum or Pressure Controlled Atmosphere

Induction Melt Systems Designed for Vacuum Atmospheres

Our Vacuum Induction Melting (VIM) systems are the leading vacuum induction melt systems used in production today. VIM systems use and induction furnace, located in a vacuum/inert atmosphere chamber, to charge, melt, refine and cast silicon material; this allows for the chemistry to be continually adjusted until the precise purity is achieved. Impurities are removed by chemical reaction, disassociation, flotation and volatilization.

Inductotherm Melt Benefits:

Ability to Melt and Cast in Vacuum or Controlled Atmosphere
Multiple Charging Systems for Rapid Melting of Silicon Charge
Extensive Data Acquisition through the Latest PLC and PC SCADA Monitoring Controls
Designed for Vacuum or Pressure Controlled Atmosphere

Electromagnetic Cold Crucible (EMCC)

Inductotherm manufactures electromagnetic cold crucible furnaces for the refining of metallurgical grade silicon and the casting of multicrystalline silicon ingots. Our innovative process utilizes a segmented water-cooled copper crucible for refractory-free induction melting. We are always improving, developing, and refining EMCC Technology to increase its efficiency.

Features of Our Electromagnetic Cold Crucible Furnaces:

Robust Segmented Copper Crucible Machined from a Single Forging
Frequency Machined Induction EMCC Power Supplies
Stirring Inherent with Refining in the EMCC Promotes Homogenous Mixing in the Melt
Computer Controlled Withdrawal Rate Provides Five Times the Growth Rate than that of a Traditional Multicrystalline Directional Solidification Casting Furnace

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-Switch^TM 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-Switch^TM 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.