Silicon rods appear "clouds"”
Thread Content
After the reduction furnace is started to feed at high pressure, a "cloud" shape appears on its surface, but the furnace does not leak. Is it because the temperature inside the furnace is too low?
The oxygen content exceeds the standard and the dew point fails.
The hydrogen replacement failed, resulting in high nitrogen content.
Please tell me on the second floor, is oxygen allowed to exist in the reduction furnace? ! How can we say that the oxygen content exceeds the standard? ?
It is usually a sign of oxidation and there is no qualified replacement in the furnace.
Can you explain it more clearly upstairs? I have a small sample of uneven "clouds", similar to the one discussed with the annual ring thank you.
That is the oxidation interlayer, and the oxygen content in the reduction furnace exceeds the standard. Generally, the oxygen content is required to be below 3 ppm, and the dew point is below -75 degrees.
The poster didn't make it clear. Did you test the surface of the silicon rod when the material was cloud-like?
It is the surface of the silicon core that presents a "cloud" shape.
Dude, the silicon rod is oxidized. Either trichlorosilane has water or oxygen, or the hydrogen is not qualified and there is water or oxygen. The interlayer has not yet been formed. The interlayer is inside the silicon rod and the oxidized surface is covered.
Well, I agree with LS. Under normal circumstances, hydrogen should contain water. Generally, there should be no water or oxygen in trichlorosilane. The dew point of hydrogen is not up to standard. When water enters the reduction furnace, the silicon is oxidized by the oxygen element in the water.
I don't think the oxygen content is excessive. If the feed starts to flow, then the flow rate is not too small. How can there be oxygen remaining in the furnace? It may be that the hydrogen gas or the carbon content in the material is high.
Yesterday, when we drove the car, we found that there was a black cloud-like thing on the silicon core just after feeding it! The problem may be that the carbon content in the material is high, and the temperature of the heating water in the evaporator is too high, causing the content of the material entering the furnace to be too high...
What color do the clouds look like? We generally say it is blue and has an oil-like color. It is the oxide layer that appears on silicon mandrels. I have seen it a lot. Looking at the drawing process, it is usually caused by the oxygen content of the gas source exceeding the standard. If such a situation occurs on polysilicon products, it is usually caused by oil leakage.
If r is colorful, it means that the oxygen has not been completely replaced. If it is only blue, it means that the nitrogen has not been completely replaced. It is recommended to check the valve to prevent colored silicon problems caused by the valve not being closed tightly.
It is recommended to check hydrogen and nitrogen dew points
When the hydrogen dew point is unqualified, or the effect of pumping out the air is not good.
What should the excess oxygen content or high water content (high dew point) be like on the silicon rod? Recently, it was discovered that the surface of the silicon rod is either blue cloud-like, or black, and it is found that this situation only occurs on the surface. I don’t know why.
The blue color is due to high N content, the color is due to oxidation, the black color is due to low-temperature silicon, and the yellow color is amorphous silicon. If the water content is high, SiO2 white crystals will generally be generated.
The "cloud" shape on the surface of the silicon rod refers to the shape or color of the silicon rod? At this time, the silicon rod in the furnace is red. Can you see various colors? If it is in shape, it may be that the surface temperature of the silicon rod is too high and the deposited silicon is in liquid form.