Research To The Influential Factors Of Metal Impurity In The Process Of Polysilicon Production

As the natural environment pollution and the destruction of the ecological environment and the depletion of available resources problems increasingly serious,the development,promotion of clean and efficient use of environmentally friendly renewable energy has become the core of the social attention.Solar energy is an inexhaustible,in endless supply renewable energy,no pollution to the environment,fully meet the current requirements of environmental protection,energy saving and emission reduction which is given priority to with solar photovoltaic power generation have attracted the most attention.One of the main raw material of solar photovoltaic cells is crystalline silicon.There are two kinds of metal impurity in the polysilicon,one kind of metal impurity come from raw material,another kind is caused by pollution in the process of casting crucible.Among them,occupied the main part of metal impurity content in raw material of polysilicon.Polycrystalline silicon metal impurities including surface metal impurity and body metal impurity.Body metal materials mainly come from polysilicon products production.It is easy to remove other elements by distillation method,but cannot completely remove,they can only be reduced as much as possible.The external environment of other elements in polycrystalline silicon surface,we call it a polysilicon material on the surface of metal impurities.Polycrystalline silicon surface metal impurity mainly contains Na,Mg,Al,K,Ca,Ti,Cr,Mn,Fe,Co,Ni,Pb,Cu and zinc,Mo,W,a total of 16 kinds of elements.And metal impurity on the surface of sources for the environment,personnel,and auxiliary materials,mainly in silicon material storage,crushing and packing.In this paper,using inductively coupled plasma mass spectrometer to detect the key process and contact material influence on polycrystalline silicon sheet metal impurity content,especially the effects of packaging materials.Through the analysis found that impurity precipitation of special material is lower than the total impurity content of precipitation of plastic film;Ordinary metal impurities total is higher than thousand grade packaging bags;Contact with different packing bag after a certain time,ordinary bags in polycrystalline silicon surface metal impurity content rise more.So,choose the thousand bag packaging have less impact on polycrystalline silicon sheet metal impurity.