The present invention relates to a thermal processing method for wafer. A wafer is placed in an environment filled with a non-oxygenated gas mixture comprising deuterium gas and at least one kind of low active gas, and a rapid heating processing process is performed on a surface of the wafer to heat the wafer to a predetermined high temperature. Then, the wafer is placed in an environment filled with an oxygenated gas mixture, and a rapid cooling 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.