The invention relates to preparation and
purification methods of
silicon tetrafluoride and belongs to the field of
fluorine chemical engineering and
electronic industry gas. The preparation method comprises the step as follows: a
silicon-containing substance and a
fluorine-containing substance are mixed to react to produce
silicon tetrafluoride. The purification method comprises steps as follows: the to-be-purified coarse product, namely,
silicon tetrafluoride, and a
reactive material for purification react to produce coarse product Mm(SiF6)p or Mn(HSiF6)q, then
thermal decomposition is performed, and purified
silicon tetrafluoride is obtained. With the adoption of the preparation method, no acid or corrosive liquid substances are used, the silicon-containing substance and the
fluorine-containing substance, particularly a gaseous fluorine-containing substance, react to produce
silicon tetrafluoride, fewer impurities are introduced, the purity of the product silicon
tetrafluoride is higher, the preparation method has the advantages of high safety, simplicity in operation, high yield, economy and the like, fewer waste acid and residues can be produced, and environmental
pollution is lower; with the adoption of the purification method, high-purity silicon tetrafluoride gas can be obtained, and the content of
impurity (SiF3)2O and HF is extremely low.