Why Quartz Crucibles Deform
In the process of crystal pulling, with the rise of the level of the crucible, the protruding part of the quartz crucible deformation will collide with the guide cylinder, which will directly lead to the serious consequences of not being able to pull the crystal. If the deformation position occurs in the melt, in the process of crystal pulling with the liquid level falling, the bulge will gradually reveal the liquid surface, then the crystal rods have been pulled out will touch the bulge, such as not stopping the furnace in time will occur the crystal rods fall down serious accidents.
（Diagram: Schematic structure of quartz crucible）
Causes of quartz crucible deformation
Improper loading method: The contact between the material on the liquid level line and the quartz crucible is in the state of surface contact, which is easy to hang the edge during the melting process and lead to the deformation of the crucible. The upper part of the crucible is fully loaded with small fine materials, which is easy to happen when the lower part of the crucible has been dissolved, and the upper part is in the state of crystallisation, which results in the deformation of the crucible.
Excessive temperature: Since the melting point of silicon is 1420°C, the general temperature of the melt is around 1550~1600°C. If the temperature of the melt is too high, it will be very easy to be deformed during the melting process.
Low temperature: When the temperature of the molten material is low, the material on the upper part of the crucible is easy to be melted or non-melted in contact with the wall of the crucible, and when the lower part of the material finishes melting, the upper part of the material that has been hung up on the edge of the block will be deformed by pulling down the quartz crucible.
Raw material problem: The quality of raw material is uneven, the metal impurity is much higher than the original polycrystalline, and the acid washing process is not perfect, which also has a great influence on the normal use of the crucible, and it is mainly manifested in the easy occurrence of serious crystal precipitation.
Crucible quality problems: Quartz crucible in the production, cleaning, packaging by staining occurs precipitation (including the liquid level above the line of the part) so that the original thickness of the quartz crucible will be thinned, the strength is also reduced, easy to occur deformation. In addition, the wall thickness of quartz crucible is too thin, the strength is not enough, also easy to occur crucible deformation.
