Polycrystalline Silicon
Polycrystalline silicon manufacturing process 【Reduction process】
Polycrystalline silicon
A number of fine (about 8 mm) silicon seeds are positioned in a metal reactor (reduction furnace) and heated by electric current to about 1,000℃ or higher. A gas containing a mixture of the refined high purity trichlorosilane vapor and hydrogen is then discharged in the reactor. Silicon is deposited on the surfaces of the silicon seeds, growing rods of polycrystalline silicon. The purity of the polycrystalline silicon in these rods is extremely high, reaching an 11 nines level. By-products, such as silicon tetrachloride and hidrogen gas, are recovered and reused.
Finishing 【Machining/manufacturing processes】
The polycrystalline silicon manufactured in the reduction process is cut with diamond cutters or other means into shapes appropriate for its projected use. It is then etched with mixed acid to dissolve the polycrystalline silicon surface, and washed with pure water before visual inspection, packing and shipping.
Reduction process
Inspection process
Polycrystalline silicon properties
Our high quality polycrystalline silicon products are at an ultra-high purity level of 99.999999999% ("11 nines"), and used as a material to produce the monocrystalline silicon which plays a central role in the semiconductor wafer industry.
Main applications
Material for producing monocrystalline silicon for semiconductors
Purity/analysis
| Contaminant | Purity | Method of analysis |
| Phosphorus concentration | ≦0.18ppba | Photoluminescence measurement of a single crystal |
| Boron concentration | ≦0.05ppba | |
| Aluminium concentration | ≦0.05ppba | |
| Arsenic concentration | ≦0.05ppba |
Physical properties
| Boiling point | Melting point | Specific gravity |
| 3280℃ | 1420℃ | 2.34（20℃） |