Does nitrogen affect the purity of polysilicon?
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The raw gas used in the device is not pure; it contains a small amount of nitrogen. What is the impact of nitrogen on the purity of polysilicon? If there is an impact, what range would be reasonable for controlling the nitrogen content in the feed gas?
This depends on which unit reaction it is in If the temperature is not very high and the pressure is not very high, nitrogen finds it difficult to react with other substances; therefore, under normal conditions, nitrogen has little impact on the purity of polysilicon
According to the foreigners, it has an impact and needs to be removed; the N2 content is almost zero
It indirectly affected the purity of polysilicon due to the formation of silicon nitride, and directly affected the purity of hydrogen
If reduction occurs, the presence of nitrogen leads to the formation of yellow silicon nitride, which affects product quality
:Curse: Does argon have an impact? :shut up:
Nonsense; take a look at what temperature is required for silicon to react with nitrogen first This is the information from the website, http://www.mgnet.com.cn/new_view.asp?id=2929; even so, what is the reaction temperature in the reduction furnace at relatively high temperatures? As is well known, nitrogen reacts with silicon under high temperature and pressure. The formation temperature of silicon nitride on metal silicide particles is lower than the melting temperature of metal silicide (<1410°C), and the amount of silicon nitride produced is also less; however, the presence of small amounts of iron, silicates, and other low-melting-point substances accelerates the synthesis of silicon nitride. In the second stage (1410–1500°C), nitrogen is completely dissolved in the molten metallic silicon, while the number of silicon nitride crystals increases. A 22% volume expansion during the reaction blocked the pores, thereby limiting further diffusion of nitrogen into the semi-finished product. Silicon nitride synthesized at 1350–1370°C has a more uniform structure and phase composition
The nitrogen content (in the recovered hydrogen) should be kept below 1500 ppm; the specific value must be adjusted accordingly based on the quality of the product and the production volume
The formation of silicon nitride requires a temperature of over 800 degrees in a reduction furnace.