Czochralski monocrystalline silicon technology

The technological process of Czochralski silicon includes raw material preparation, silicon ingot cutting, slice cleaning, crystal growth, monocrystalline silicon rod processing, monocrystalline silicon rod cleaning and monocrystalline silicon inspection. This process requires high-purity silicon ingots and a series of complicated equipment and processes.

Monocrystalline silicon is a monocrystalline silicon material grown from a single seed crystal, which has the characteristics of complete lattice and few defects and impurities. According to the growth mode of monocrystalline silicon, it can be divided into zone melting monocrystalline silicon (FZ silicon) and Czochralski silicon, and the processes involved include zone melting method and Czochralski silicon.

Compared with zone melting method, Czochralski method can support the production of large-size silicon wafers such as 12 inch, while zone melting method is used for the production of silicon wafers of 8 inches and below. Therefore, Czochralski method is the mainstream crystal growth process at present.

The main process of Czochralski method includes polysilicon raw material feeding, polysilicon melting, seed crystal, necking, shoulder setting, equal-diameter growth and ending. The preparation process of Czochralski method is to heat the polycrystalline silicon raw material placed in a crucible to make it into a solution.

The single crystal seed can contact with the silicon solution through the seed shaft arranged above the furnace body. Through the rotation and up-and-down movement of the seed crystal axis, the silicon liquid will condense and grow along the surface of the seed crystal, and finally form a single crystal ingot.

Difference between monocrystalline silicon and polycrystalline silicon

Crystalline silicon is divided into monocrystalline silicon and polycrystalline silicon according to different crystal orientations. The difference between monocrystalline silicon and polycrystalline silicon is; When molten elemental silicon solidifies, silicon atoms are arranged into many crystal nuclei in the diamond lattice. If these crystal nuclei grow into grains with the same crystal plane orientation, monocrystalline silicon is formed. If these nuclei grow into grains with different crystal orientations, polysilicon is formed.

The difference between polysilicon and monocrystalline silicon is mainly in physical properties, such as mechanical properties and electrical properties. Polycrystalline silicon is not as good as monocrystalline silicon. Polycrystalline silicon can be used as raw material for manufacturing monocrystalline silicon, and it is also the basic material for solar cells and photovoltaic power generation.

Monocrystalline silicon is the purest substance in the world, and the general semiconductor devices require the purity of silicon to be above 6 9s (6N). The requirements of large-scale integrated circuits are higher, and the purity of silicon must reach nine nines (9N). At present, people have produced monocrystalline silicon with the purity of129 (12n).

Refer to the above content: Baidu Encyclopedia-Monocrystalline Silicon