|
|
Ingot production
High purity solar-grade virgin polysilicon is loaded into a quartz crucible for melting in a furnace. The molten polysilicon forms a single solid crystal rod as it cools and is pulled from the crucible by a puller using a rotating upward motion in a vacuum chamber. The size of the ingot is determined by the size of the wafer that it will be used to produce, with 125 mm by 125 mm wafers being produced from ingots that are approximately 150 mm in diameter and 156 mm by 156 mm wafers being produced from ingots that are approximately 200 mm in diameter. Finished ingots are tested for resistivity, lifetime and other specifications before they are processed for wafering.
|
|
|
|
|
|
|
|
|
|
|
Wafering
Each silicon ingot is cropped and squared using sophisticated cropping saws and squarers before they are sliced into wafers. The corners of square ingots are grinded before slicing. We are currently using 120 micron wires for slicing the squared ingots into wafers, the process of replacing such 120 micron wires with 100 micron wires are tested, as the use of thinner wires cause less polysilicon wastes in the slicing process. We are currently capable of slicing wafers with a thickness of approximately 170 microns, which allows us to enjoy higher production yields.
Cleaning and inspection
Sliced wafers are cleaned and inspected by our quality assurance team before being packaged and shipped to customers.
|