Abstract: A method and an apparatus for preventing silicon hole defect formation on a silicon wafer after a wet cleaning process are disclosed. In the method, a supply tank and a cleaning tank are provided which are connected together in fluid communication by a conduit. The conduit is cooled by a wrapped around cooling tube and a cooling water flowing through the tube at a temperature of less than 20° C. The apparatus of the wet cleaning station may further include a pump for transporting an aqueous solution of ammonia from the supply tank to the cleaning tank, a safety overflow conduit for protecting the supply tank that holds the aqueous solution of ammonia, and a flow control valve in the conduit between the supply tank and the cleaning tank. The present invention novel method and apparatus effectively prevents the formation of ammonia vapor in the mini-environment that surrounds the cleaning tank and the rinse tank.