The control of defects on the wafer is a critical task for nano-scale memory devices to achieve high yields. Even though supercritical CO 2 drying technology has been available for more than 10 years, its application in 300mm wafer fabrication process still lacks an effective solution for the control of particles and metallic contaminant generated. To address this, the authors studied the CO 2 purification process and found that most of particles on the wafer after supercritical CO 2 treatment were found to be organic contaminants from the CO 2 raw material. A CO 2 purification system with an activated carbon absorber demonstrated superior performance for removing organic contaminants from the CO 2 . The metallic contaminants, coming from the supercritical chamber's stainless steel parts, were decreased by aging of the supercritical fluid at a high temperature.