With the rapid development of the domestic solar photovoltaic industry, the market demand forquartz crucible has been expanded, which is mainly used for quartz crucible Czochralski silicon single crystal production, due to raw materials and production process problems, a lot of domestic quartz crucible has the disadvantages of low softening point, short service life, easy offdepression, and purity is not high due to crystallization the phenomenon, has recently beenfound, as long as the quartz crucible wall is coated with a layer of can promote devitrificationmaterial, which can greatly increase the service life of the quartz crucible and the crystal growthrate. This can promote the devitrification material, compounds containing barium ion for general use. This is because the equilibrium segregation coefficient of barium in silicon is very small, so it will not affect the quality of wafer.
The usual practice is to be coated with a layer of quartz crucible wall contains water of crystallization of barium hydroxide, barium hydroxide in this layer will form barium carbonate and carbon dioxide in the air. When the quartz crucible is heated in a single crystal furnace, barium carbonate will break down to form barium oxide, barium oxide and quartz crucible with theformation of barium silicate. Because of the existence of silicic acid barium, which form a dense layer of tiny white silica quartz crucible wall. The tiny white silica crystals are difficult to penetrateand peeling solution, even if the peeling is soon to be dissolved out, therefore, can improve thequartz crucible substantial life and long grain yield. In addition to form a layer of silica whitecrystalline quartz crucible wall is good, it can increase the strength of quartz crucible, reduce thehigh temperature softening. |