Method and device for preparing electronic grade trichlorosilane by deeply removing trace phosphorus and boron impurities

The invention provides a method for preparing electronic grade trichlorosilane by deeply removing trace phosphorus and boron impurities, which comprises the following steps: rectifying and separating a trichlorosilane crude product to sequentially remove heavy component impurities and light component impurities to obtain a trichlorosilane product containing trace phosphorus and boron impurities difficult to remove; the method comprises the following steps: evaporating a trichlorosilane product containing trace phosphorus and boron impurities which are difficult to remove into trichlorosilane steam, introducing the trichlorosilane steam into a fluidized bed phosphorus and boron impurity adsorption device, and fully contacting and mixing the trichlorosilane steam with a modified activated carbon adsorbent under fluidization, so that the trace phosphorus and boron impurities in the trichlorosilane steam are fully adsorbed by the modified activated carbon adsorbent and are removed; the modified activated carbon a