The present disclosure provides a method of heating a spin on coating (SOC) film on a wafer. The method includes actions S401 to S405. In action S401, a heating apparatus is provided. The heating apparatus includes a bake plate and an electromagnetic wave generator. In action S402, the bake plate is heated by a heating unit disposed in the bake plate. In action S403, the wafer is placed on the bake plate of the heating apparatus. In action S404, the electromagnetic wave generator generates an electromagnetic wave to heat the SOC film. The electromagnetic wave generated by the electromagnetic wave generator has a frequency within a range of 1 THz to 100 THz. In action S405, the wafer is removed from the bake plate of the heating apparatus.