Photovoltaic Silicon Wafer
SUMCO has developed an electromagnetic casting method that enables stable manufacturing of high quality multi-crystalline silicon ingots. It is a quite unique technology which we are proud of.
1. Raw silicon
“Eleven-nines”(purity 99.999999999%) silicon is used as a raw material
2. Electromagnetic casting method
Raw silicon is molten from high frequency induction heating using induction coils. The high frequency induction heating system allows an object to induce electric current using the same principle as an IH heater. Since the electromagnetic force generated by the induction coil provides molten silicon with the force directed toward the center, the liquid silicon can maintain high purity without making contact with the crucible. By lowering the ingot slowly, the liquid silicon cools gradually and crystallizes.
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3. Square multi-crystalline silicon ingots
The ingot manufactured by the electromagnetic casting method is the largest silicon crystal for solar cells in the world with a length of 7,000 mm.
4. Multi-wire saw
A multi-wire saw capable of cutting four silicon blocks simultaneously is used to ensure wafer quality and productivity that is state-of-the-art for the industry
5. Cleaning
The sliced wafers are carefully washed in a two-step process consisting of an initial wash and a finishing wash.
6. Inspection
To ensure that stringent customer standards are met, each wafer product is inspected by an experienced inspector who is a specialist in the field.
The electromagnetic casting method is a process by which high frequency induction inside a cooling crucible is conducted to melt raw silicon and use powerful electromagnetic energy to suspend the molten silicon and form ingots continuously. This enables high quality silicon ingots to be manufactured without the molten silicon ever coming in contact with the crucible.
Advantages of silicon wafer manufactured by the electromagnetic casting method
- Continuous casting process improves uniformity and maintains quality.
- Small variations in the conversion efficiency can provide stable performance and quality.
- High resistance to breakage of the wafer enables a reduction in thickness, leading to the saving of raw materials.
SUMCO's silicon wafers demonstrate these excellent features and are highly evaluated by the customer as easy-to-use wafers.
