The present invention relates to a thermal processing method for wafer. A wafer is placed in an environment filled with a gas mixture comprising oxygen gas and deuterium gas, and a rapid thermal processing process is performed on a surface of the wafer. As a result, a denuded zone is formed on the surface of the wafer, deuterium atoms, which may be released to improve characteristics at an interface of semiconductor devices in a later fabrication process, are held in the wafer, and bulk micro-defects are formed far from the semiconductor devices.