Laser purification of silane: impurity reduction to the sub‐part‐per‐million level

摘要

Selective ultraviolet photolysis of AsH3and PH3impurities in SiH4has been employed to photochemically purify the SiH4. At ambient temperature, initial impurity levels of 50 ppm each of AsH3and PH3in SiH4were reduced to less than 0.5 ppm upon irradiation with a 193‐nm ArF excimer laser. Lowering the temperature at which the photolysis is carried out to below ambient results in a substantial reduction in the laser energy required for impurity removal.