to accomplish removal of impurity compounds which would otherwise accumulate in recovered chlorosilane circulating in a deposition reaction system and thus to yield polycrystalline silicon of stable quality application_number US 201415031226 A description embodiments of the present invention will now be described with reference to the drawings fig1 is a first exemplary flowchart for illustrating the method according to the present invention for producing semiconductor grade high purity polycrystalline silicon in the example shown in this figure step a s 101 uses purified tcs chlorosilane obtained in step e s 105 described later and hydrogen as raw materials to deposit polycrystalline silicon and thereby produce semiconductor grade high purity polycrystalline silicon in recent years semiconductor grade high purity polycrystalline silicon of high quality has been demanded which has a level of purity obtainable by producing polycrystalline silicon by the siemens process using a chlorosilane material containing 0 070 ppba or less of phosphorus and 0 010 ppba or less of boron as impurities exhaust gas resulting from the deposition reaction of the step a s 101 contains hydrogen and tcs remaining unreacted and further contains for example dcs and stc formed as by products this exhaust gas is typically cooled and separated into condensable chlorosilane and other gases such as hydrogen and hydrogen chloride in the example shown in fig1 step b s 102 performs this separation in an exhaust gas recovery installation the condensable chlorosilane obtained by the above separation is delivered to step c s 103 in which the chlorosilane is subjected to separation by distillation in a chlorosilane separation column and.