The difference between monocrystalline silicon and polycrystalline silicon is that when molten monocrystalline silicon solidifies, silicon atoms are arranged in a rhombohedral lattice into many crystal nuclei. If these crystal nuclei grow into crystal grains with the same crystal plane orientation, single crystal silicon will be formed. If these crystal nuclei grow into crystal grains with different crystal plane orientations, polysilicon will be formed.

The difference between polycrystalline silicon and monocrystalline silicon is mainly manifested in physical properties. For example, boule crystal，in terms of mechanical and electrical properties, polycrystalline silicon is inferior to single crystal silicon. Polysilicon can be used as a raw material for drawing single crystal silicon. Monocrystalline silicon can be said to be the purest substance in the world. Generally, semiconductor devices require silicon purity of 6-9 or more. The requirements for large-scale integrated circuits are higher, and the purity of silicon must reach 9 9s.

At present, people have been able to produce single crystal silicon with a purity of twelve nines. Monocrystalline silicon is an indispensable basic material in modern science and technology such as electronic computers and automatic control systems.

The production process of polysilicon mainly consists of high-purity quartz (high-temperature coke reduction) → industrial silicon (pickling) → silicon powder (adding HCL) → SiHCL3 (after rough distillation) → high-purity SiHCL3 (reactive CVD process plus HCL) H2) → high Pure polysilicon.

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