Reduction production process of polysilicon and reduction furnace for production

Abstract

A reduction production process of polysilicon and a reduction furnace for production thereof. The process includes mixing SiHCl3 with H2, spraying it from the bottom air inlet and discharging it from the gas outlet; passing cooling water through the jacket of the reduction furnace; The final silicon is deposited on silicon rods and other steps. The mixed gas is injected from the bottom air inlet of the reduction furnace and discharged from the top air outlet. The reduction furnace includes a base, a shell, multiple pairs of electrodes, thin silicon rods, an air inlet and an air outlet. The shell has a jacket, and the water inlet and outlet are fixed on the jacket. The air inlet is fixed on the bottom, and the air outlet is fixed on the top head. It can avoid the diffusion of the rising air column at the bottom and make it fully contact with the silicon rod. There is no fluid dead zone at the top, and the silicon deposition rate on the top of the silicon rod is high. Gas temperature is easy to regulate. The turbulence of the gas in the furnace is strengthened, the mass transfer is enhanced, and the residence time of the gas in the furnace is long. Greatly increased one-time conversion rates.

Description

technical field [0001] The invention belongs to the technical field of polysilicon production, and more specifically relates to the reduction production process of polysilicon and the improvement and innovation of the production reduction furnace. Background technique [0002] Traditional polysilicon production generally adopts the Siemens method. It is based on HCI (or CI 2 、H 2 ) and metallurgical grade industrial silicon as raw material, hydrogen as reducing agent, and SiHCI 3 Reaction, reduction to produce polysilicon. The Siemens method has been improved and developed to the third generation technology. The first-generation technology only recycles unreacted hydrogen in the reduction furnace, which is only suitable for scale production of less than 100 tons. The second generation is based on the first generation and realizes SiCI 4 Recycling, increasing the deposition rate, thereby expanding the scale of production. The third generation technology adopts activate...

AI Technical Summary

Problems solved by technology

[0008] 1. The rising air column will diffuse at the bottom, resulting in partial fluid not fully contacting the silicon rods, that is, a short circuit is generated and directly discharged from the air outlet, which reduces the one-time conversion rate of production

[0009] 2. There is a dead zone of fluid flow at the top, especially when the furnace is just started, the inflow of gas is low, and the injection gas column cannot reach the top. In addition, the density of hydrogen is low, and an area with high hydrogen concentration is easy to form at the top, resulting in silicon rods The upper silicon deposition rate is low; since there is only one gas outlet on the base and it is close to the center, there is also a dead zone for fluid flow around the bottom, which also results in a low silicon deposition rate

[0010] 3. The gas temperature in the furnace is not easy to control

Since the flow rate of the gas changes greatly from the start of the furnace to the discharge, and the diameter of the silicon rod is also increasing, if the surface of the silicon rod remains at 1100°C, the above two factors will cause the temperature of the gas to change, and it is difficult to adjust

[0011] 4. Low one-time conversion rate

However, the increase of the gas flow rate shortens the residence time of the gas in the furnace, which will lead to a low one-time conversion rate.

The above-mentioned contradictions cannot be solved with the existing structure and operation mode of the reduction furnace

Images