Abstract: An amorphous region is formed by implanting an impurity such as As into a semiconductor substrate having a natural oxide film. The amorphous region is divided into a heavily doped oxygen region in which the concentration of oxygen is equal to or higher than a critical value and a lightly doped oxygen region in which the oxygen concentration is lower than the critical value. Then, oxygen ions are implanted to expand the heavily doped oxygen region throughout the amorphous region. Annealing is performed such that the reordering rate of the amorphous region is determined and the annealing temperature is determined by using the relationship between the annealing temperature and the reordering rate. By adjusting the oxygen concentration in the amorphous region to the critical value or more, the reordering rate can be adjusted to a nearly constant low value and the accuracy and reliability of temperature measurement is increased.