Method of cleaning silicon material with a sponge

摘要

A method of cleaning a silicon material using a polyvinyl acetal sponge material. The sponge material is purified by an extracting process which includes alternating exposure of the sponge material to acid and oxidizing solutions. The extracting process permits residual amounts of calcium, zinc, sulfate, arsenic, barium, cadmium, chloride, chromium, copper, iron, lead, manganese, magnesium, mercury, nitrate, potassium, selenium, silica, silver and sodium to be 2 ppm or less. Following the extracting process, the silicon material is contacted with the sponge material to thereby clean the silicon material.